As a Midwesterner, it is absolutely bonkers to me how common it appears to be for HVAC systems to get installed in attics.
Don't do that. Stop doing that! WTF?
That's bad enough, but then you go and run the ducts up there, too?
Y'all.
If you keep the system and the ducts within the space you're trying to heat and cool, you don't have to account for any losses, now, do ya?
Put the air handler in a utility closet. Run ducts /below/ the ceiling. Enclose with soffiting if you must.
The end.
This is a test rant for a future video that may or may not happen.
But seriously, I cannot fathom how HVAC stuff in attics (or crawlspaces!) got normalized. Especially in new construction.
You virtually never see that around here (the most common application is old homes with radiators for heat who want to add central air) and for good reason!
@TechConnectify
Do you live in a warehouse? Better solution is to insulate the attic.
Or, my preference, mini-splits.
@AudraTran You should absolutely insulate the attic, sure.
But around here? Nothing ever goes up there. It's strictly storage if anything.
We mostly run ductwork through the floors. If you have a finished basement, that's essentially zero energy waste. If it's unfinished, some heat is needed anyway so the minimal losses are fine and useful.
How this isn't standard practice everywhere is beyond me.
@TechConnectify I think it’s a thing for homes with no basement. I’ve seen it for homes in Texas.
@jterhorst Still, though, it's entirely weird!
The *only* benefit is that you gain a bit of floor or storage space.
Personally, I think eliminating the loss of a damaged ceiling from a plugged condensate drain is worth some floor space.
Then, keep the bloody ductwork out of the bloody attic. Drop the ceiling down a foot along the perimeter and put the ducts there.
@TechConnectify so, as a former Arizonan, it’s for several reasons:
1. No basements
2. Originally the whole unit was on the roof, so this protects the air handler from the sun much better
3. You typically have the air output registers in the ceiling so the cold air can fall through the room anyway, so why not put the ducts up there too
4. It was un-used space, so why not
@LordOphidian The thing about soffiting and running the ducts below the ceiling was to address both points 1 and 3.
As to point 4 - I feel like making servicing the thing such a pain the ass just to save some floorspace is... well, I wouldn't go that route.
And I've seen some of those rooftop package units out West. Another thing that I cannot fathom, frankly, but whatever.
@TechConnectify maybe that practice dates back to when energy was cheaper? Def had that in our previous house which was from the 1970s
@thomasfuchs I figure it must.
I was at my brother's recently and the fact that ever time the A/C came on there was a blast of hot air first made me want to tear my hair out!
People designing homes in mild climates need to venture up here, methinks.
@TechConnectify have you seen Matt Risinger’s discussion of this on https://buildshownetwork.com ? He’s a big proponent of extending the conditioned envelope of the home to include the attic to, among other things, remediate this issue.
@StarTracker I haven't seen that video, no, but see to me that perspective can only come from somebody who is used to air handlers already going up there.
That's just not a thing we /ever/ do here except in weird circumstances. The attic is strictly structural and hardly anyone ever goes up there period.
@TechConnectify Can't speak for the general case, but in ours (heat pump, Nova Scotia, ftr):
- We have two closet upstairs, they're in use: one laundry, one storage
- We got an attic unit specifically to run vents to each room upstairs
- The attic unit needs an intake, 20"x20", because it moves a lot of volume; infeasible for a closet
- It also needs to run refrigerant and drainage to the exterior (and then down to the ground); also not closet-compatible
- That's the unit for just the top floor
@delta_vee An important consideration here is that I'm mainly talking about home design. If you're retrofitting stuff, convention flies out the norm.
We would /never/ design a home from scratch where any of the HVAC stuff is in an unconditioned space like an attic. They may go in basements, but those need some heat, too, so it all works out. And we design return ducting in, too.
But, circling back to retrofits, this is a key reason I expect mini-splits to become a lot more common soon
@TechConnectify We've also got ductless for the main floor and basement - even for retrofits, it's not either/or.
Also our attic is insulated; dunno if that's common down there or what...
@delta_vee The attic itself is generally uninsulated here, but there's a crapton of insulation above the ceiling.
So the rest of the house is insulate /from/ the attic.
@TechConnectify the roof top units pre-dated the others as far as I’m aware since they could be put in place using the exist swamp cooler ducting.
Problem is, the units would get worn out by the sun and the controller boards would burn out a lot (at least from my experience as a kid with ours needing repair often).
@TechConnectify Service wise, it’s probably hard on the techs, but access isn’t too bad, since only the air handler is put in the attic and they didn’t seem to do too much to it when checking it. The condenser outside is where they would spend most of the time.
Soffits are… not appealing visually and I only ever saw them for houses where they added ducting or some sort of piping after the house was built.
@LordOphidian All I gotta say is I'd hope you give up a bit of visual perfection to gain a ton of efficiency.
I said this elsewhere but I was just at my brother's house near San Diego. The fact that when the A/C kicks on there's a blast of HOT air at first is infuriating to me.
For the record, soffits are uncommon up here. We generally run ducts through the floors and use central wall voids for return ducting. Seems to work just fine for cooling, tbh, but people disagree.
The youtube build channels I've seen don't seem to advise against that, but they say you should make sure your attic is insulated.
Do you think that's still a bad idea in that case? If yes, why?
@Hawkwinter If your goal is to turn the attic into a conditioned space, then sure.
But if your attic is just gonna stay an attic, keep it the hell out of there.
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@TechConnectify don't want to have to hide ducts? Great, that's what a mini split is for
@mirahimage Mini-splits are going to be a game-changer for efficiency in the parts of the country that doesn't think through ducting.
Up here, though, we'll probably just stick with central systems. We're not losing anything!
@TechConnectify central wall voids like between the studs? Seems too narrow, plus there’s fire breaks half way up?
In my houses in Arizona I never took note of a blast of hot air when it came on, but maybe I’m just conditioned to it.
@LordOphidian Honestly not sure how firebreaks work into it (that might be a regional thing) but A) you've got a lot of walls and B) you can use more than one bay.
There are two wide vents (probably 36" wide) high up in the living room in my parent's home. If you removed them you'd find nothing behind them but the back of the drywall in the adjacent room.
At the bottom, though, they join a big return trunk that heads to the air handler. It's super normal up here.
@jterhorst @TechConnectify Texas builders should visit Minnesota. We still have slab on grade homes, but they’ve managed to figure out the mysterious art of putting a utility closet just off the garage and ductwork between each floor.
@TechConnectify You’re not wrong, you’re just advocating the wrong solution. Conditioned attic spaces with insulation under the roof deck is the best approach for slab on grade new construction with high solar loads and AC demands.
@transcendentape But that's the thing, isn't it? A conditioned attic space becomes a conditioned space.
If you want to spend the money to turn it into one, I ain't gonna stop you. But most people just leave their attic an attic for one reason or another. And if that's the route they've chosen, ducts and the air handler should go somewhere else.
Plus, in many of the homes I'm talking about, the attic ain't tall enough to turn into a useful space anyway.
@TechConnectify I guess we got lucky then. I'm currently set up in Chicago and our place has the HVAC in a closet in the unit. The vents are all on the ceiling tho
@ADisorderlyFashion Is this an apartment/condo building? That's pretty common.
The thing there is you still don't have losses, really, unless you're on the top floor. You just end up heating/cooling your neighbors a bit and decreasing their load.
@TechConnectify Apartment, but very small. It's 4 units total split between 4 floors
@TechConnectify so, at least in Arizona, it’s been code for a long time to have a 2x4 (or 2x6 if you are lucky and have thick walls) that runs horizontal across the midpoint between the studs so you don’t have airflow up the void. Helps prevent fire from spreading up the wall voids.
Sounds like your duct would have to be less than 3.5” deep, and could only run half way through the wall.
@LordOphidian I'd have to look into specifics of our firebreaks but either there's a carve-out for bays used as a return or else the specifics are different.
Full-disclosure, though, I haven't toured a single-family home newer than ~2010. Code might have changed.
I now live in a townhome which uses the main stairway as the return. The air handler is in the room at the bottom and sucks air in through a large grill. Bedrooms have a vent through the wall to connect to the hall.
@LordOphidian Still, though, the ducts actually distributing conditioned air never venture into the attic because, from everything we've ever known about energy use, /that would be silly/
The attic is for framing the roof and maybe storing some knickknacks if you feel like it.
@ADisorderlyFashion Are the vents level with the rest of the ceiling or are they boxed in?
I'm just curious - there are always exceptions!
@TechConnectify As far as I can tell, they're level with the ceiling
@TechConnectify right, typically in Arizona there’s just the one return that is in the ceiling near the air handler location (so you don’t have to run the duct very far) and the return is 20”x24” or so. My two story home had two, one at the top of the stairs and one down a hallway, but based on the filter cleanliness, the stairs did most of the work.
@LordOphidian Well right, and for context, there's a return grille in /every room/ with our setup. So one or two bays per room feeds down to that trunk line. The filter is then right before the furnace/air handler.
Homes built slab-on-grade usually have a big grill on the side of the closet with the furnace in it. Just like my new place. If they're smart, ducts will stay below the attic level. For two-story homes, lower level will get ceiling registers, upper level floor registers.
@ADisorderlyFashion Interesting. Hopefully the ducts themselves are insulated, then.
@TechConnectify
If you think that's bad, at some point builders in North Texas decided that water heaters up there were a good idea, too, combined with ventilation that couldn't be closed. In February of 2021, a lot of people learned the hard way why that was a terrible idea.
@Eastcheap *facepalm*
I say this with 100% sincerity (and a hint of pride): If you want to learn how to build a climate-resilient home, just come up here. We've been doing it since forever because we have to.
@Eastcheap And, unironically, it's a big reason I'm staying put.
My home can handle 100°F weather with stupid humidity just as well as it can handle -20° weather because that's just what happens.
We cannot take design shortcuts, and we don't.
@TechConnectify as someone whose air handler is in a basement and ducts in soffits, I agree it is strange. I wonder what the numbers are on how much efficiency is lost by placing an (insulated) unit and duct work in what is ostensibly a super-hot Texas attic
@StarTracker I can't speak to Texas, but around San Diego (where my brother is) after the A/C's been off for a while, you notice a blast of hot air when it comes back on.
I haven't been up into his attic to check the ducting situation, but I have no doubt they're insulated. It's just that anything sitting in a hot attic for an hour is gonna get, well, hot.
@TechConnectify I didn’t take many pictures of it in back when we were building the house in 2005, but you can kinda see that they insulate the ducts, so it helps reduce that energy loss.
Also I’m used to attics having blown in insulation outside the platform under the air handler, so you don’t really store anything up there.
@LordOphidian Thanks for the photos.
It's still puzzling to me, though. Like, sure, you can insulate the ducts but if you just keep all that stuff out of the attic... you just don't have to. You don't even have to think about it!
That's pretty much my whole deal. I can't really fathom the "why" beyond it saves a bit of floorspace and/or you prefer a flush ceiling.
Perhaps it's because I've always been energy conscious, but those why's aren't enough for me.
@TechConnectify Wouldn't it cost pretty much exactly the same as long as the attic is properly insulated? I mean, if you live in a climate where you pretty much only need cooling, it's going to be a lot more efficient to cool the top parts of the house than the bottom parts because the cold air will just end up sinking down thruout the rest of the house. I guess a bigger surface area on the roof would slightly increase heat transfer into the space, but I'd wager that it's rather insignificant compared to the space savings it can offer.
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@diligentcircle I think you may be missing that most attics just... aren't properly insulated. You insulate the rest of the house /from/ the attic with tons of insulation above the top floor ceiling.
That's what I mean by conditioned space. Around here, the attic is hot-as-fuck in the summer and you'll freeze to death in the winter because it's not conditioned. It's dead space meant only for framing the roof and, possibly, low-priority storage.
Putting equipment up there is... insane to me.
@diligentcircle Case-in-point is a lot of California housing.
Roof slope tends to be gentle (no snow loads to deal with) so you couldn't even stand up there. You're not going to turn that into conditioned space because there's no point.
Yet ducts are run through the hot AF attics routinely, and air handlers get stuck up there often, too. To me, it's utterly puzzling.
@TechConnectify luckily my attic has a lil fan that will blow hot air out during the summer, completely unrelated to the houses full AC but makes it nice getting stuff up/down.
@TechConnectify I know that, it's exactly how the house I live in is set up, but we're talking about designing new houses, right? And in the design of a new house, there's no reason you couldn't just skip the insulation between the attic and top floor and instead insulate the attic itself. I don't see how that's a nonsensical design choice in hot climates. (And when you're talking about retrofits, pretty much anything goes because you're stuck with the constraints of the house as it already exists.)
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@diligentcircle Only if you designed the attic to be large enough, and that's the thing:
More ceiling height in the attic means higher roof pitch which is more expense, and also requires more insulation, too.
It's a lot more expensive than just a bare-minimum structure to hold up a sufficiently pitched roof.
@TechConnectify it saves quite a bit of floor space though, since the air handler is way larger than any closet in the house besides the master walk-in, so you’d have to make a bed room smaller or something to build a special closet for it.
I suppose you could put it somewhere in the garage with the water heater, but why when you want the cool air coming from above you and you have a bunch of unused space up there?
Not, that your wrong about energy use, but it’s not 100% of the design goal.
@LordOphidian Eh. I dunno if I'd say "quite a bit"
Around here, your furnace and water heater are generally best buds. And something no bigger than a typical bedroom closet can easily house both. That's exactly what I've got in my place. Maybe 25 square feet.
And I have the luxury of a washer/dryer closet upstairs! In many homes you'd have a utility room in the core for all that stuff
This is really just an exercise in comparing norms - but I'll still never see equipment in the attic as such!
@TechConnectify Do you have any numbers on the difference in cost (assuming a brand-new construction) between the two methods?
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@diligentcircle Not offhand but my parents built the home they live in now and simply adjusting the roof pitch was a considerable expense.
@TechConnectify I know some condos in Texas have their HVAC unit mounted horizontally above the bathtub.
It was weird seeing that for the first time, considering I'm used to all HVAC units being upright/vertical.
@saiarcot895 ...above the bathtub? That's super weird.
Apartments/condos have always been more of a hodgepodge around here but if they've got central heating and cooling it's usually either a MagicPak (which is a packaged furnace/AC thing mounted to an exterior wall) or a conventional A/C and furnace. Same ductwork conventions apply, though MagicPaks are sometimes quasi-outdoors.
But, PTACs are common, too, and even some newer buildings have central heat via radiators but through-wall AC
@TechConnectify doesn't putting the unit outside the house envelope allow you to run gas backup?
Never seen ducting run outside the envelope... yeah, that seems to be missing the point
@kilpatds I don't quite get what you mean. I have a gas-fired furnace that is entirely within the envelope, except the combustion section is /technically/ outside thanks to the intake and exhaust pipes
Caleb
@TechConnectify We just moved to Eastern North Carolina and literally every house we looked at had this setup.
The insulation is for the home (and the ducts), not as an attic living space. It's more expensive but it drastically improves efficiency, largely for the reason you mentioned.
@AudraTran okay, to clarify (already this has caused confusion elsewhere), I don't mean to say that the attic has not been insulated from the rest of the house. There's boat loads of insulation up there! Usually they fill the rafters all the way up with blow-in cellulose or something like that. Something like R-50 is code here.
But that's it. Everything above that layer is essentially outside, and *none* of the home's system components are up there apart from wiring.
@AudraTran *that's* what gets me.
An attic gets bonkers hot (and cold 'round here!) so as far as we're concerned, you just don't put anything up there aside from knickknacks you are comfortable keeping in temperature extremes.
If you're finishing an attic (if it's even big enough) and want to heat/cool it, then sure. Have at it! But that's pretty rare where I live, and you would probably stop calling it the attic at that point
@StarTracker @TechConnectify The reason why ducts are run in the attic is because cold air sinks, so when the air is coming out of the air handlers, the cold air blasting out mixes with the warm room. If you have cold air coming out of bottom vents, the air doesn't mix well and stays on the bottom of the room.
Notice that what I just wrote is awful during the winter. Texas homes are not made to be efficient during winter and are uncomfortable. Everything is cold and drafty.
@StampedingLonghorn @StarTracker I gotta say that I honestly don't buy the whole "ceiling vents are better for cooling" thing because it gets pretty dang hot here, too, yet nobody seems to complain that the vents are in the floor.
I mean, they're forcing air out of them at a decent clip and air seems to mix fine. Plus ceiling fans help even further.
Regardless, you can have them overhead but also not in the attic! Just have to learn to live with a partially dropped ceiling
@StarTracker @TechConnectify There is an initial blast of cold air coming out during the winter. The water takes a long time to heat up on a cloudy, cold day because the water heater and plumbing is in the attic as well. The gas bills are just as bad as the a/c bill.
@TechConnectify
I understand what you meant. I think you're missing what I'm saying. If you put the insulation on the inside of the roof, as opposed to where it's typically laid (on top of the ceiling) the ducting is insulated, and the house is more efficient. This is not done for the purposes of occupation, it's for increased efficiency.
But regardless, the ducts themselves should be insulated from the attic conditions.
@AudraTran I'm only missing what you're saying in the sense that it doesn't necessarily matter when nothing's up there in the first place.
Like, we often don't insulate ductwork *at all* because, well, when it's all within the conditioned space, there's no need.
Now, is a house with insulation both above the ceiling /and/ below the roof more efficient? Perhaps. But the M.O. here is just to go bonkers with the ceiling insulation and let the attic breathe easily (often with an extraction fan!)
@TechConnectify
Hi. California, our house is concrete slab.
AC condenser is out back but the HVAC blower and furnace are in the attic.
It allows nice fat tubes carry the air back to the blower and then out to the rooms, I don't think it would be possible to have the airflow capacity we have without the unit in the attic.
When A/C kicks on, first blast is cool.
@SocialJusticeHeals Oh it's totally possible for it to not be in the attic yet still have stellar airflow.
You can run a 8X24 rectangular trunk along the perimeter of the home in a soffit. Might even be simpler than the octopus of ducting I've seen in some attics.
That seems to be the key aversion - many would rather have a clean ceiling than put efficiency first.
@SocialJusticeHeals What I think is key is that when you don't go into the attic, all those little losses that you have to watch out for just evaporator.
Ducts leak a little bit? Not a problem.
Insulated ductwork? We hardly even know what that is here. You don't need it when the system is entirely within the conditioned space.
I think California just has an aversion to what we call a "utility room"
Over here, furnace and water heater are almost always together. Seems the opposite in CA.
@SocialJusticeHeals The number of water heaters and washer/dryers I see in CA garages somewhat confirms that.
Up here in the Great Cold North, you generally can't put water pipes in the garage. So that's out of the question.
Then we'd usually share the same exhaust for the water heater and furnace. So they go together quite often.
And since that's gotta go inside, might as well make a room out of it and stick the washer/dryer in there, too
Of course, if you have a basement, it all goes there
@TechConnectify I just got through the whole thread, and you are mostly correct. The attic floor is really best for insulation, not the slopes of the roof, and because of this ducts should avoid being placed in the attic. The nuance of what alternatives make sense is a lot more complicated.
I’ve been an energy auditor and QC inspector for insulation and energy efficiency projects for 13 years, if you want me to go over the details with you at some point hit me up.
@junio I can tell there's a lot of nuance, especially with noise, heating/cooling prevalance, etc. but I'm relieved to know the attic thing is as bonkers as it seems!
Methinks ductless mini-splits are going to be quite the game changer for retrofits. Once HVAC contractors stop being allergic to them...
@TechConnectify ductless mini splits are great, especially for adding AC to a house that wasn’t set up for it, but here in the US they actually don’t make systems for small rooms. We have 6000 BTU units and if you’re going to install one in every room like every HVAC contractor will recommend we need sub 2000 BTU systems.
If I were building new, I’d install ducted heat pumps to manage per room loads appropriately and keep the system efficient.
@junio But most of them can run at that output, no?
I think a lot of conventional wisdom is about to be thrown out the window once vari-speed compressors and EEVs become normalized.
And, what irritates me endlessly, is that those are pretty much standard equipment now in commodity mini-splits from Asia but for some reason the domestic manufacturers hardly build any.
@TechConnectify @LordOphidian there's a house in my neighborhood that would just blow your mind. It's a flat roofed house with the unit and all of the ducting on top of the roof in the open air!
@TechConnectify @LordOphidian found it. Here's *just* the roof.
@LordOphidian @TechConnectify I do NOT want to imagine their summer power bill!
@asjimene @LordOphidian At least they painted it white...
Seriously, though, that place needs ductless mini-splits to rescue them ASAP
@kaleb_haugen Yeah.
I guess I'm mostly intrigued by ducts/systems in attics that are utterly useless for anything else. Like, my brother's attic sure ain't gonna be fun to be in as you couldn't stand up there yet they crammed the air handler and all the ducts up there.
Just... why?
@kaleb_haugen @LordOphidian Now that's how you do it!
You sconnies are alright
@TechConnectify we're adding a second story to our house and the architect needed a little convincing to bring the ductwork under the insulation. Then the HVAC sub contractor wouldn't do it and did it the way they always do.
In the end the GC built a larger space around the duct work but I had to fight for that. I will now have half of a conditioned Attic.
Building trades are so slow to change. And there is very little regard to long term energy efficiency unless code requires it.
Oh, I also had to overcome convincing against a heat pump water heater, builder was pushing to add gas or propane for a tankless.
Location DC area.
@mwbbrown There is so much skepticism of new things in these industries and it drives me up the wall.
I'm considering a video on this topic but it's been a long time in the script oven and I'm still not happy with it. That's a big part of why we're halfway through September and I haven't put a video out.
@TechConnectify I assume so since that heat wave where we broke into tripple digit fahrenheight (40c iirc) didn't kill me. I'll know for sure this coming Winter
@TechConnectify although not super common yet (getting more so), my attic is inside the insulation envelope and is part of the heated/cooled area of the house.
@kurtisfranklin I take it that the attic is useful space, then?
That's my main hang-up, honestly. Some of it is semantic - an "attic" to me implies it's not a habitable space, and if you make it one, it's no longer an attic. And unless you're actually going to be up there regularly, why bother doing it at all?
If the only answer is to make HVAC more efficient, you could just... not run it through the attic.
@TechConnectify nope not useful at all. Think typical new construction attic, but instead of blown-in insulation sitting on top of the ceiling, the insulation is held against the roof line. Still many many inches of blown-in insulation, but instead of sitting on the “floor” of the attic, it’s held over your head.
@kurtisfranklin Then you're /really/ not selling it, gotta tell ya.
We (usually) just let the attic breathe and the blown-in insulation is something like R-50 these days.
If you're not doing anything with the space, it can get as hot (or cold) as you like without affecting indoor comfort or energy use. And if you're insulating roof rafters /in place of/ the ceiling, that honestly seems like it would be less effective.
@kazriko Do you have lower-than 8 foot ceiling or are you imagining some sort of monster duct?
Because you can totally just drop the ceiling by about 10 inches along the perimeter and run an 8X24 rectangular trunk.
@kazriko Even if it only went around the perimeter?
This is purely academic, btw, I'm not saying you should retrofit your home. Mini-splits are generally a better option for that (with some caveats) but I'm just trying to challenge norms, here.
@kazriko You know your home better than I do, definitely.
Again, just trying to push people's minds to somewhere else.
The section in this article that reads "In recent years, energy-saving designs have sought to include ducts and heating systems in the conditioned space." is hilarious to me since, y'know, we figured it out half a century ago. I'm baffled by how revelatory the concept seems to be.
https://www.energy.gov/energysaver/minimizing-energy-losses-ducts
@kazriko @TechConnectify Well mine are heat pumps, so they have indoor and outdoor portions, connected by refrigerant and power lines - it's the placement of the indoor part we're talking about
Other than ducts running from stuff in the house to the roof, and a couple of network cables, there's nothing up there.
@delta_vee @kazriko Yeah, to clarify, the condensing unit (or more properly outdoor unit since it's arbitrary with a heat pump) is always outside. I'm talking about where you put the cooly heaty blowy thing.
Ideally, you only want refrigerant to move between indoors and outdoors. Always keep the air you're paying to heat and cool within the space and you're not fighting with losses.
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@kazriko @delta_vee I just saw you post elsewhere you have a gas-fired furnace.
So, around here, that doubles as the air handler. You stick an evaporator coil above it and hook it up to an outdoor condensing unit, and that's how we do central air conditioning.
@kazriko @delta_vee At this point I'm kind of lost and don't know what your idea of normal is (which is kind of the whole point of the discussion!)
The outdoor portion of an air conditioner can be hooked up to anything, really, and that's what's known as a split system. The two heat exchangers are separated. It might be an individual mini-split head or it might be a large evap coil in an air handler for central air conditioning.
What you mean by "whole unit" eludes me
@kazriko @delta_vee Ah. I wouldn't call that a furnace - I'd call that a boiler.
@kazriko @delta_vee OK, well then you're largely gonna sidestep the original problem I imagine. If you don't have ducted heating, you're not gonna use it for cooling!
@kazriko @TechConnectify There's one other category (of heat pump anyway) which is attic-mounted (for the indoor portion, still has an outdoor unit) and has multiple ducts, but it's meant for a single floor not as a "central" unit per se. That's what I have for our top floor, plus two ductless units for the other two floors (which share one outdoor unit).
@TechConnectify The good systems can produce very low percentages of their rated capacities, but for small rooms or efficient homes, they can still be oversized. And the worse systems might only be able to go down to 50% capacity.
If heat pumps were inexpensive, this wouldn't be an issue, but where I am the average home install for one unit in each bedroom and one in the living room and maybe the dining room is well over $30,000.
@junio This is actually something I'm hoping to tackle with a video topic.
There's a lot of flat-out price gouging going on in the space. The actual equipment cost for a three-head Mitsubishi split system is about $4K wholesale. Even the most elaborate systems don't tickle $10K, so installers are absolutely profiting on the /sale/ of the equipment in addition to the work to install it.
@TechConnectify @kazriko So I actually do have central ducting for a forced-air furnace - we decided not to add the heat pump to it because the ducting is too small and thus and loud, and it can vary up to six degrees between basement and top floor - the separate per-floor units gave us better temp control
@TechConnectify The point of making an attic include d into the conditioned space isn’t to reduce the relatively minimal AC losses, it’s to deal with the condensation that results when an attic that reaches 150F and 80% humidity reaches an interior space conditioned to 75F or so. Your solution doesn’t address the fundamental problem we deal with in the South where we have night-time temperatures higher than desirable, high humidity, and no basements.
@transcendentape we absolutely face those same conditions up here in the height of summer. 95° days at 60-70% humidity are pretty common, with beastly nights, too.
Our attics, though, breathe to the outside. The main moisture issues we face are from roof leaks or old bathroom fan installs - we used to allow venting into the attic before we learned how bad that was.
Also, basements are in no way required to keep the ducting out of the attic.
@TechConnectify What is fundamentally different between a wall and a roof? A wall can be shaded from the vast majority of solar thermal load simply by building overhangs. The roof cannot.
@TechConnectify So, instead of continuing the building scheme we’ve used since before there was A/C, it’s better to remove the pressure cooker that is an attic entirely. Is it cheap? No. But in new construction, the price differential is a handful of dollars per square foot and in my area, far superior than any other alternative.
@transcendentape I mean, if you want to remove the attic space, go ahead.
But understand that for homes around here, *NOTHING* goes in the attic. The attic has tons of vents at the eaves and the peaks to keep air flowing through it. Does it get beastly hot up there when the sun shines? Absolutely! But there's a layer of R-50 insulation above the ceiling to battle that intrusion.
And that beats the pants off of any insulated ductwork.
@TechConnectify That’s precisely the problem. For an attic to not be a mold trap, it must have a tremendous amount of airflow. It doesn’t make economic sense to incorporate that into the structure with the building materials we have available today.
@transcendentape I mean, we seem to be managing it just fine.
@TechConnectify I mean, go ahead. We live in entirely different climates with entirely different residential construction norms.
@transcendentape my central point is that I think people in different climates could learn a thing or two from us. Our summers can be just as bad as down South, if less consistently. Perhaps that's the only reason our attics don't get moldy, but I'm doubtful.
You pointed to duct losses as minimal, but the first estimate I found puts them at 25-40%. That's a lot of energy being wasted and money being spent to condition space you're not in.
We just... don't do that.
@transcendentape our M.O. has largely been to treat the attic as a space which is there to frame the roof and that's it.
It's functionally outside, so once the sun sets the conditions up there equalize with the outdoors quickly. And sometimes we even use a fan controlled by a thermostat to force some airflow! But that's relatively uncommon.
From my perspective, the reason we don't deal with mold is mostly that there's nothing up there colder than ambient temps.
@TechConnectify I honestly don’t want to be an asshole here. All I’d ask is to consider the fact that you and I live in different climates, and the solution that seems obvious to you is not obvious for me. Of course I may be wrong. But there’s absolutely no one in my area incorporating your ideas in new construction at any price.
@transcendentape Oh, I don't think you're coming across that way (and I hope I'm not!)
But consider this:
https://www.energy.gov/energysaver/minimizing-energy-losses-ducts
The section "Designing and Installing New Duct Systems" is humorous because that's all we've ever been doing up here. It's nothing new!
@TechConnectify I’d really like you to re-read this reply and understand how it entirely ignores the argument I was making.
@transcendentape Sorry, to be more clear, "entirely different" feels like something of a stretch to me when, for three months of the year, we have extended periods where we might as well be Orlando with only slightly less humidity.
But, I will agree to drop that comparison.
@transcendentape However, I would like you to look into what the common causes of mold in the attic are. What I'm finding isn't convincing me that the issues are much different between climates, and bottom line it's lack of proper ventilation which is the biggest concern.
@TechConnectify “It’s functionally outside”
This gets to the heart of the matter. I don’t think you appropriately appreciate how bad attics are in my climate.
Pre-A/C, homes were built with 10 or 12 foot ceilings and windows to allow cool air in the bottom and warm air out the top. When we got A/C and started insulating walls, we ran into all kinds of problems with mold. Walls can be protected by rooves, but there’s nothing to protect the roof.
@transcendentape Well, to be honest, I'm confused by what you mean by "bad attics." Can you elaborate?
But to circle back to the climates things, when you say "started insulating walls" - this is it right here. We've been doing that *forever* because we have to. And absolutely critical to that is a nice thick blanket of insulation above the ceiling. It doesn't really matter how hot the roof (or attic) gets when you have that barrier in-place.
@transcendentape Without trying to toot my own Midwestern horn too much, that's really what I'm getting at - yes our climates are different, but we had to learn how to keep a home habitable for a reasonable cost when the outside air is at -20°F, and we absolutely have our own moisture considerations at those temps.
Bottom line, though, you're still in a battle with a temperature gradient, and lot of those lessons we learned over the decades translate nicely to cooling.
@TechConnectify As a matter of fact we have not been doing that forever, at least in my climate. This is precisely the confident ignorance that I am upset with you about.
@transcendentape OK... let's rewind, here.
This whole discussion is about regional/climactic norms. It started with my challenging them, and you described what's done in your area as "the best approach"
Really, all I'm trying to do is challenge that, and offer up what's been normal here for a long time as an alternative. Perhaps, if someone ventured to try building a home down there just like we do up here, it would be much more comfortable and take less energy to cool.
But, perhaps not.
@TechConnectify Dude, do you not see the difference? I’ve seen -20f exactly zero times. There are are likely 90 days a year nighttime lows don’t drop below 85 for me.
Your arguments simply don’t apply.
@transcendentape ...
OK, look. Heating and cooling are different tasks. Sure. You don't really need much heating.
But just as you're trying to keep hot air from getting in your home, we try to keep it *in* and that's the same thing! You're slowing thermal transfer with insulation. Which is why it also works for cooling.
Really, what I'm getting at is... perhaps the places of the country that have to battle an 80 degree temperature drop might have some lessons for other parts of the country.
@TechConnectify For sure. That’s a condition I almost never face. My general problem for eight months of the year is dealing with heat and humidity. This is related to your problem, but not at all the same.
@transcendentape And there's no disagreement from me! If I just plopped the house I live in where you live it would be wildly overbuilt for your climate.
But... I can pretty much guarantee it would cost a lot less to cool. And I guess what I'm really asking is... why wouldn't you want that?
From this side of the screen, it's like I'm saying "we cannot get away with cutting corners" and you're like "well we can, so we do" and I don't really know how to engage with that, honestly.
@transcendentape This whole thing was a discussion of norms. While I didn't specifically get into it, the self-reinforcing nature of them is something I'm trying to pick at.
To me, growing up here, the idea that anyone would ever design an HVAC system where air was distributed outside of the conditioned envelope is just, well, batshit. It might be a little more expensive to not do that, sure, but I'll bet it's /always/ worth the cost on a 10 year timeline.
@TechConnectify You could test that hypothesis by observing what good homebuilders are building.
Matt Risinger is an Austin,TX homebuilder that deals extensively with these kind of questions, and he has a Youtube channel that covers a lot of the issues we’ve covered.
@transcendentape I'm familiar with those channels, and Risinger specifically! I largely like a lot of what they feature, but there's other things I totally don't.
For instance, I think tankless water heaters are extremely overrated and a barrier to home electrification. And I'm still perplexed by the attic thing - I need to log off soon but I want to repose my thoughts here on last time in a different way:
@transcendentape What does the air handler do? It produces the cool (or warm) air that you need, and it costs you money to use it. Therefore, that air has a raw dollar cost and you probably want to minimize waste.
This is the raw crux of my whole deal. It seems entirely self-evident to me that you should put the machine that costs money to use inside the space you want it to heat and cool. And, you should keep all components of that machine (i.e. ducts) in that space, too.
@transcendentape To accept less is akin to throwing out a slice or two of bread with every loaf you buy.
Perhaps it's just my Midwestern cheapskate mindset, but I feel it's not actually hard at all to design an HVAC system to guarantee that all hot/cool air it produces stays within the envelope and accepting anything less is just... absolutely strange!
You can /completely/ design those losses out of the system, so I think you should.
Now, with that, good night.
@TechConnectify I mean, yes. We are arguing the same point. The difference is that in the south, where nighttime temps are frequently above ideal and humidity is an issue, moving the structure of the A/C down to the liveable area doesn’t solve the problem. In fact, it makes it worse. The problem in the South is the existence of unconditioned attic spaces.
I’ve never walked outside to -20F temps.
I have seen a cloud below my ceiling due to dewpoint.
@TechConnectify What you might not be appreciating is the very different response water vapor has between-20f and 80f versus 150f and 80f
@transcendentape Oh no, I appreciate this but... again, in the summer this absolutely something we deal with. And to be honest, I feel like putting a cold thing in the attic is /way worse/ than not doing that.
In fact, why is keeping the AC entirely in the conditioned space worse? I need you to explain that because truly I'm not seeing it.
Our homes just flat out don't have ceiling penetrations into the attic other than an access hatch and electrical boxes. The attic, as I said, is outside.
@transcendentape Yes, it gets extremely hot up there when the sun beats down. But when it sets? It cools off real fast and equalizes with the outside air.
The only parts of the building that are cooler than ambient temps are below a sea of cellulose insulation. None of the attic structure is cooler than ambient, and that's why I'm kind of perplexed by the mold angle. I don't see that reality changing even when it's hotter and more humid.
@TechConnectify We both seem to be arguing for including the infrastructure of the A/C in the living space. Were I differ is that I am arguing for the elimination of the attic space, as modern building methods allow us to remove it entirely and place the insulation on the roof deck.
@transcendentape Really? I was not picking up on this /at all/
But I guess that means we're in agreement!
I want to add, though - I think we weren't helped by how we imagine attic space differently. To me, it's dead space. Nothing ever goes up there. And that's /precisely/ why I have found putting an air handler/ductwork up there to be batshit.
And I would say that in places where that's normal, the move seems to be to transform it from attic to... something else?
@transcendentape I honestly think that's a big point of contention here.
To me and most of my fellow cheapskates, the attic does one thing - it frames the roof. That's it. We put a butt-ton of insulation above the ceiling and miiiiight store some knick-knacks up there but it's accepted to be a terribly hot and cold place that is literally only there so water (and snow) falls nicely off the roof.
Dual-purposing it for other building systems has simply never been in question for us.
@TechConnectify “Why is keeping the A/C entirely in the conditioned space worse?” Because in my climate, in conventionally built homes that aren’t built to the standards that we both are advocating for, those losses are necessary to ensure the attic doesn’t become a pressure cooker.
@transcendentape ehh... to be honest I still think there's something we're talking past each other on, here.
In my head, you can take any existing home where you are, get the HVAC out of the attic and run ducts below the ceiling, then patch up all the holes, add the sea of cellulose that's normal up here above the ceiling, and you'd be right where I want you to be.
No mixing at all of conditioned air with attic air, and sufficient ventilation prevents mold.
Am I missing something?
@TechConnectify Dude, you don’t have to argue with me about how bad it is to put mechanicals in the attic. It’s just that that is the common thing to do here. HVAC and even water heaters are thrown up there. Makes for good billing when there’s a problem.
@transcendentape Haha, I know it's common! I'm basically wondering aloud how the hell that got started.
@TechConnectify No, you’re not missing anything except for the fact that very few people look at a 1200 square foot home and think, “How can I reduce the usable size?”
@transcendentape OK, if we're there then, this is all buttoned up.
To be clear, I'm not saying people should sacrifice floor space and get the air handler out of the attic. If they want to maximize both energy efficiency and usable space, I would probably push towards a mini-split setup.
But what I /am/ saying is... next time you build a home, add another 50 sq feet for the air handler closet. That's only been in my head 'til now, but that's where I've been from the start.
@transcendentape Like, I'm not really bothered by homes with air handlers in the attic when it was a retrofit.
But I /am/ bothered when new construction emulates that for no apparent reason.
@TechConnectify Absolutely no arguments from me… except that if you’re building a new home in my climate, you should consider eliminating the attic as a non-conditioned space, regardless of where your HVAC is.
@transcendentape Agreed. I would, however, be curious to know whether there have been comparisons between a conventional attic with R-50 or maybe even R-75 insulation above the ceiling and a home where the attic has been eliminated or otherwise mildly conditioned.
But at this point, that's just academic!
@TechConnectify At least in my area, there are a great many reasons to be upset with new home builds.
@transcendentape And in all honesty, this is something I take Midwestern Pride in.
We've largely got building systems figured out. I've actually been delighted by the design of my new home - the ducting was run very thoughtfully and even employs what I call "strategic leakage" to protect pipes in vulnerable areas from freezing.
But, it ain't perfect! Sure wish I had better windows...
@transcendentape Anyway, to wrap this up, that's the "you" I'm really speaking to. Not the general homeowner outside the Midwest, but the contractor or home designer. I really feel like there's a lot to learn from a home built to withstand our climate - even if it's just to eek out a bit of frugality.
This might turn into a video, and if it does - thanks for helping me organize my thoughts!
@TechConnectify It’s not only academic, but entirely unrealistic. The only way you could ever find thise R values is if you paid someone to build your house for you.
I can wave a magic wand as well.
@TechConnectify You’re essentially requiring a second structure to be built around the structure simply to hold the insulation. What in the world do yo propose to use as a regular building material with R50?
@transcendentape Blown-in cellulose! That's pretty common and has an R-value around 3 per inch. Create a sea of it in the attic above the celling and once you're above the rafters you can easily be at R-36. Go to 18 inches and you're at R-54.
Code in Illinois is actually R-49 right now.
@TechConnectify And, more importantly, why?
Solar, wind, and hopefully storage and distribution will catch up soon. Advocating for R50 is not just unrealistic but possibly counter-productive in almost all situations.
@transcendentape Just in case I've misled you, I just mean above the ceiling to the attic. We don't go to that extreme for walls.
This isn't exactly a code reference but this is what we do here
https://insulationinstitute.org/wp-content/uploads/2015/12/IL-2012.pdf
@transcendentape And like, if this surprises you... that's kind of my whole point!
When I said we insulate the living space from the attic, I /meant/ it. Works just as well when it's -10 up there at night as it does on a hot summer day at 150 degrees.
@TechConnectify water vapor is what you I think you aren’t considering, but I accept your point.
@transcendentape Eh, I still feel as though with enough breathing (which, again, we absolutely ensure with roof and soffit vents) it's not a concern. The structure is only cooler than ambient for a few hours in the morning before it starts baking, and then when it's cooling off it's all really hot and water won't condense on it.
Breathing is critical, though, and I'll accept it may not be enough where you live with consistent grossness.
@TechConnectify I feel like we’re now arguing about finer points that I am not at all qualified to argue about.
@transcendentape Honestly, same. But I can attest that mold problems in attics are not at all common here.
It's usually either signs of a roof leak or as I said earlier the home was built when we thought "sure, just blow steamy shower air into the attic, it'll be fiiiine"
@TechConnectify I can attest that you and I are not in the same climate and I don’t understand why you continue to make this point.
When I started this conversation, I said, “You're not wrong, you're just advocating the wrong solution. Conditioned attic spaces with insulation under the roof deck is the best approach for slab on grade new construction with high solar loads and AC demands.” I stand by that claim.
@TechConnectify I’m not particularly interested in arguing the point further, as I doubt both of our qualifications.
@transcendentape Oh, sorry, I wasn't trying to be argumentative. I was just reinforcing my observation that we don't seem to have moldy attic problems.
Now, my gut tells me that a conventional Midwestern attic with an HVAC system inside of it would indeed be prone to moisture issues due to the fact that leakage from the ducts and/or cold surfaces of the equipment would encourage condensation. So, imo, removing the equipment would solve the problem.
But I have no proof beyond my gut
@transcendentape So by no means can I assert the same would be true where you live. I don't know the specifics of what causes moisture in attics for you.
Was just giving food for thought
@TechConnectify
You think that's bad? They also run the pvc drain line from a unit on the second floor, then run it underneath the house and then the garage out back (various places in Baldwin Park Florida).
Like, they want it to clog and cause a mess when the shut off switch failed to work.
@ChemicalTribe That's a big part of what irks me!
I get doing this if the house was built without air conditioning. But any time a new home gets built without planning for the air handler to stay within the conditioned envelope (where it will also be easier to service!) I want to scream.
@TechConnectify
Yep, places there are around 20 years old. And for homes around 2010, they put in an air vent in the ceiling, to the outside above the gas fireplace, which gives wonderful 95° temp 75° dewpoint air during the day, and I couldn't legally advise them to close it off.
So dumb.
@ChemicalTribe *screaming*
I just... I don't get it. It's hard not to sound arrogant when I say this, but home builders in the South really ought to come up here and take a look around. We need to keep heat inside the home when it's -20° outside and - shocker of shockers - those techniques /also/ make the home more energy-efficient when it's hot outside!
This guide paints what we've been doing here forever (keeping ducts in the conditioned space) as revelatory.
https://www.energy.gov/energysaver/minimizing-energy-losses-ducts
@ChemicalTribe Code here - code! - is now that the ceiling have R-49 insultation above it.
We treat the attic like it's outside and nothing goes up there but venting and some electrical work.
Does a hell of a job holding heat in in the winter, and also shielding the living space from the baking attic in the summer.
@TechConnectify When I was younger: My family owned and operated an HVAC business in Ohio. I used to help with installs all the time and I can tell you that the vast majority of systems, even in Ohio (the midwest) was done in attics and/or crawl spaces/basements. Crawl spaces were the worst, by far. Our family made a name for ourselves being the only area installer that used sheet metal instead of the flex duct because critters would get into the flex stuff and chew through it, build nests, etc.
@TechConnectify I think the piece you're missing here for southern climates is R value only defines resistance against heat flow assuming there's no air flow. The issue with blown insulation is that it doesn't provide an air barrier (nor vapor). And that's where the whole summer humidity problem comes from. The dew point in an attic can approach 80 degrees and that blown insulation is going to do nothing to stop condensation from forming on the 70-ish degree ceiling drywall, light fixtures, etc.
@jeremy_akers I'll admit I don't know enough about those mechanisms. We have stretches every summer where nights are just as hot and humid as in the South, but perhaps they're brief enough moisture problems aren't an issue.
However, I question whether insulating the roof rafters makes more sense than having a proper vapor barrier above the ceiling.
@TechConnectify You’re hung up on insulation, while I’m trying to tell you that the existence of the unconditioned attic is the problem. Do you think no one in the south has considered insulation?
As you tighten up the building envelope, which is a requirement for efficiency, you exacerbate humidity problems that were previously dealt with by expected losses. Your gut feeling is simply not at all appropriate in my climate.
@TechConnectify From the most basic level, observe where vapor membranes are applied in your climate versus where they are in my climate.
@TechConnectify Now, given the fact that if I am not actively venting my attic, then I can expect it to be at least 50F higher than my conditioned space for maybe five months out of the year. 24/7. That’s not equivalent to outside temperature. And blown in insulation doesn’t have the vapor barrier on the correct side.
There’s a reason different climates have different building norms.
@TechConnectify Actively vent the attic? Why? When nightime temps are above 85F for three months what does actively venting the attic prove? The problem for me, in my climate, is the attic.
@TechConnectify We used to deal with this problem by having twelve foot ceilings and double hung windows and leaky construction with no A/C. Now that we are striving towards efficiency, the attic is the problem, and there’s a good history of home construction to show that attic insulation alone isn’t the solution.
I understand you also have hot days. I’m not talking about hot days. I’m talking about the fact that the lows do not drop below desired temps for months on end.
@TechConnectify Putting the mechanicals in the attic is silly in my eye, but it saves a bit of space in new builds. Putting the ducting in the attic simply makes sense when compared to whatever it is you are advocating. If it is your argument that the ductwork should be in the conditioned space, I agree. There’s a clear advantage to bringing the attic into the conditioned space that exceeds the idiocy of having ductwork inside the living space in my climate.
@transcendentape I feel like you missed some replies in the order I sent them - you seemed surprised by R-49 being code, or at least I pieced that together when I floated R-50 ceiling insulation and you said nobody would do that (or similar).
Regardless, I will grant you that I don't know the fundamentals of combatting moisture well enough to speak intelligently on the subject. However, I still question which approach makes more sense:
@transcendentape Make the attic part of the conditioned envelope, or create a moisture barrier between it and the living space then leave all mechanicals out of it.
Assuming a vapor barrier could be added to the R-50 ceiling insulation that's code here now, then why bother conditioning the attic at all? That's really the crux of my bafflement, and the normality of putting mechanicals up there where you live may cause the less effective thing to be standard due to legacy factors.
@transcendentape But, I will clarify what I mean by actively vent the attic:
In general, we don't prevent outside air from entering the attic. Quite the opposite, actually - we encourage it. Soffit vents below the eaves and roof venting help to rapidly equalize the attic temp with the outside temp once the sun sets.
Some homes also have mechanical ventilation in the form of an exhaust fan in the roof that switches on when it's above ~120 up there. The idea is to fight solar heating.
@transcendentape But that fan will shut off by nightfall.
Now, hopefully we agree that moisture will only condense (or at least problematically so) on things that are colder than ambient air. If mold weren't an issue prior to air conditioning becoming commonplace, that reinforces that notion.
So the real challenge is how to most cost-effectively prevent that both in terms of construction costs and ongoing energy costs. And here's the rub as I see it:
@transcendentape Putting the air handler and ductwork up there will obviously promote condensation more than if it weren't up there in the first place.
So, to what extent are the differences between construction techniques to mitigate that?
I can't answer that question - I can only guess. But it's really what I'm trying to pick apart because it seems like quite the confounding variable.
@jeremy_akers The other thing I'm really trying to pick apart is how much worse are moisture problems in attics when the equipment is up there?
Simply putting the cold-making thing and the ducts that distribute the air it makes cold inside the attic seems like asking for trouble. How much less would you have to battle moisture if you just removed it?
@TechConnectify There’s no reason for the air handler to be in the attic except for space saving and perhaps noise issues(?). That wasn’t common even 20 years ago. Ductwork is in the attic because there’s no other place for it to be if you are slab on grade. You can make the case that you should still have a crawl space even if you don’t need a basement to get below frost heaving, but for whatever reason, that’s just not a thing here anymore. I’m not sure why.
@TechConnectify So basically, if you don’t include stupid foot wide traces throughout the ceiling, the ducts go in the attic. Also, I need to remind you that the moisture problem isn’t simply the fact that the A/C infrastructure is in the attic. The moisture problem is because the attic is ventilated, and that’s precisely why eliminating the conventional attic is such a good idea in my area.
@transcendentape I know the moisture issue would persist even without the equipment up there, but surely it would be minimized, no? The ducts and equipment itself become much colder than ambient temps *inside* the home.
So that's really what I'm trying to ask - how much more effort are you spending to combat moisture merely because of that practice?
And the fact that you described the solution to slab-on-grade without resorting to ducts in the attic as stupid tells me a lot about sticky norms
@TechConnectify How do you add a vapor barrier above the ceiling in an attic with wooden trusses?
It was almost impossible until a few years ago with closed-cell foam insulation.
@transcendentape I mean, it seems pretty straightforward to me. Simply adding a floor up there to box-in the cellulose insulation ought to work as OSB itself is a vapor barrier. And lots of people do that anyway to make walking around in the attic (and using it for storage) more practical.
@TechConnectify I keep my house at around 75F and about 35 relative humidity throughout the nine months of the year or so I am using A/C. During at least half of the year, both the outside temp and humidity exceed that. Simply venting the attic makes as much sense as opening up a window.
@TechConnectify If you think OSB is a vapor barrier, then it’s clear I’ve wasted my time and I’ll bow out until you do the very minimum to educate yourself.
@transcendentape It's listed as an impermeable vapor barrier here:
https://en.wikipedia.org/wiki/Vapor_barrier
And like... I don't see why it wouldn't be! You could use mastic to seal it against the joists if you want to be extra-careful.
But, I'm willing to be wrong.
@TechConnectify I’m not interested in arguing with you any longer. I’ve never seen your house, but I know for a fact that your attic is not sealed with OSB and I think if you gave it half a second to think about why it wouldn’t work, instead of posting a wikipedia article that shows a wall, you would be able to understand why.
You do you, I’m done. Contact home builders or do better google-fu.
@transcendentape I will gladly be done!
I'll just say this - you wanted to know how to prevent moisture from forming on the backside of the colder ceiling drywall. At least, I think that's what you were asking.
Doesn't seem like rocket surgery to me to add an air and vapor barrier above the foot of cellulose insulation on top.
I really think we're talking in circles because how we imagine attics to function is too different.
@TechConnectify Get your ass up into your attic and place a vapor barrier above your blown in insulation with OSB. And when you’re done with that, come on down to Texas and fix all of our other problems as well.
@TechConnectify Maybe I could have made it more obvious, but despite the fact that you clearly don’t have any fucking clue what you’re talking about, it’s easy to insulate a wall. If you insulate the roof deck, it’s almost the same. When you insulate the ceiling, fuck off with your vapor barrier with conventional home building.
@TechConnectify But of course you wouldn’t be expected to know why that’s a problem. You’ve just spent two fucking days arguing it isn’t while I’ve been trying to explain to you why it is. So please, do your homework. I’m done.
@transcendentape Alrighty, I can't help it - you said earlier that it was the act of adding air conditioning that led to mold problems. Is that correct?
It's not simply that the attic is /there/ it's that there is now a place being maintained colder than ambient temperatures near to it.
Now, as far I as can tell, homes here are built like highly-insulated boxes. That box than gets a roof plopped on top of it.
I truly don't know what you mean by "it's easier to insulate a wall"
@transcendentape Basically, we keep going back to the central contention here of "turn the attic into a conditioned space" vs. "keep the attic /separate/ from the conditioned space"
Air handling equipment up there is what's blurring that line, imo. And if for some reason your homes /aren't/ built like boxes first and then the roof is framed such that it sits atop that box, I won't be surprised but I can't imagine what that looks like.
@TechConnectify No!
Most homes built in my area prior to 1960 or so don’t even have insulation.
The problem is that when you start gunning for cooling efficiency by restricting air movement, then in a hot, humid environment, you’ve got a significantly different set of problems than if you’re trying to keep an area warmer than the outside environment
@transcendentape Okay, we are just on very different wavelengths, then.
I think you might have assumed I've been talking about retrofits and stuff. I'm not - every existing building will face tons of challenges. I've been trying to pick apart new construction differences
No doubt where and how vapor barriers need to be placed varies between where you live and where I live. I can see that very well!
This whole time I've been trying to nail down why new a home built here would be bad down there
@transcendentape And it seems to me that the immense effort we spend to keep heating from escaping /into/ the attic would do just as fine a job at keeping the heat up there from coming back in.
Undoubtedly the details of the vapor barrier would need to change! There's no disagreement there. But you seem to think it would be impossible to adapt the principles of Midwest home design to Southern climates and, well, I don't.
For real, though, let's just end this. It's been nice chatting
@TechConnectify WTF are you arguing? Better insulation in new builds? Guess what, that’s what we’re doing! And the fact that the air handler and the water heater is in the attic has exactly nothing to do with that.
Oh boy. Let me put it this way.
When I hear you say "you should advocate for making the attic conditioned space" all I can think of is - why? Unless you are going to actively use that space for living, that's more air to heat and cool.
And we're stuck with some circular logic. You say it's fine to put air handling stuff up there, but that only makes sense when that space is conditioned. Which I believed you agreed to early.
I'm saying... just don't.
@TechConnectify If your argument is that ducting should be in the conditioned space… good news! I agree. Except instead of your proposal, I think it’s better to eliminate the major structural issue by including the attic into the conditioned space. It needn’t be 75f up there, but the air up there IS NOT outside air, so humidity isn’t a problem.
@transcendentape I agree with you 100% that the techniques required to effectively isolate the living space from the attic would need to be different in your climate vs. mine. There is literally no disagreement.
I strongly question, though, whether bringing the attic into the envelope actually makes sense both in terms of immediate construction cost and ongoing energy needs.
@TechConnectify This is a perfect example of the difference between our climates. You look at the attic as an unnecessary area to condition, while I look at the attic as a burden to shed.
@transcendentape I agree! And I just want to pick at this one last time:
You had attics before air conditioning, right? Was their existence problematic prior to then?
If yes, then great - ditch 'em! Don't just make them part of the conditioned space, get rid of them entirely and do vaulted ceilings or something.
But if not, I'm left asking how much the mere fact that ducts (which leak) and equipment are up there is contributing vs. the fact that the space below is cool.
@TechConnectify I am not at all advocating for what works here in stupid hot and humid environments to be rilled out in the north. What I am asking is that you consider why what works for you may not be the best choice here.
@transcendentape That, truly, was the crux of this whole thing to me.
I probably sounded like I thought you could just build homes like we do with zero modifications, and to be clear I don't think that's the case /at all/
@TechConnectify I’m not quite old enough, but I feel confident saying that prior to 1960 or so most homes here weren’t built with insulation or air barriers at all. The common concept was that a structure had to ‘breathe’
@transcendentape OK, so to bring this full circle - we still build our attics to breathe! And moisture is, in fact, the main reason. Plus, we need to minimize ice dams when the snow melts.
The attic is separate - entirely - from the rest of the house. So it's old principles and techniques up in the attic, and new principles down below. Never the twain shall meet.
@TechConnectify When A/C was introduced, we started becoming interested with buttoning up the envelope, which led to many new problems. Regular roof ventilation now introduced humidity, and there’s been many successive construction standards that have tried to juggle stopping airflow while allowing moisture flow. What I think is standard now is to prevent every bit of airflow and to deal with air quality separately
@transcendentape That barrier for us is mainly thermal. You're right, we don't deal with hot and beastly conditions enough for moisture to be a concern thanks to cooling.
But the barrier is /everything/ and I feel like it could be adapted and perfected in your climate. You'd end up with a very modern structure sitting below a very old-school structure, and (if you ask me) the key to making that work is keeping modern systems and concepts out of the old-school part of the structure.
@TechConnectify It’s remarkable to me that you think you are arguing for keeping modern systems and concepts when in fact you are arguing for precisely the opposite in my case.
@transcendentape It might sound like that, especially from your end, but to me - it's just as baffling to know anyone ever thought the attic is a good place for equipment to go!
And, brass tacks, are the modern concepts where you are born from that norm?
If yes, then from my perspective it's like "y'all took an unideal approach, made that normal, and are now adapting how you do things to fit that norm rather than question the norm"
@TechConnectify Maybe you could do a YouTube video on how climate dictates roof structure?
@transcendentape When we get right down to it, that's where I keep coming back to.
Our disagreement - I think - comes primarily from how attics are used differently. For us, they just... aren't. We don't put stuff up there, they're solely to frame the roof.
For you, they've become a frustrating part of the building system design which you have to battle. And if anything, I'm asking why that battle started. Because perhaps, they say, the winning move is not to play :)
Anywho, I should go
@TechConnectify I don't know. But in my Austin Texas home, I spray foamed the attic (The roof side) and it made a huge difference in our ability to control humidity. It seems silly to me to try and create a vapor barrier at the ceiling below the attic... which is damn near impossible given all the holes in a ceiling (Lights, fans, vents, etc) vs just putting it at the roof. It's not really more costly to do the vapor barrier at the roof either.
@TechConnectify 1.) I have been irrationally upset with my failure to convey that what I view as obvious is not the same as what you view as obvious. Here’s my restart.
As you know, in the south where the ground doesn’t freeze, there’s no economic reason to have a basement. Many homes are still built with crawl spaces where ducting could be placed, but that building style has seemingly fallen out of favor because slab on grade is cheap and easy.
So, where do the ducts go? In the attic.
@TechConnectify 2. That wasn’t a problem through the 80’s, as homes weren’t air tight enough to matter. This is where our concept of insulation and HVAC functionally diverges due to climate differences. You seem to be worried about heat loss through the ceiling. I want heat loss 3/4 of the year. My problem is humidity. The more efficient the building envelope becomes, the worse humidity becomes unless I am able to exclude ambient air from the structure. That’s easy for me to do in walls
@TechConnectify 3. But it’s very hard for me to do in the attic. Vapor barrier goes on the hot side, and my hot side is my attic for easily 9 months of the year. It is not feasible to install a vapor barrier above insulation in an attic unless you make the roof deck the insulation and vapor barrier and treat it the same as walls. This is, I think, the fundamental difference between building for my climate and building for yours.
@TechConnectify 4. Since the 80’s, we’ve had a problem with the more efficient the building envelope is, the more likely you are to have mold problems. It’s got nothing to do with the ducts, as that would be an easy fix… and including them in the living space would not eliminate the problem. The issue is that for all of at least 3 months and for the majority of 9 months, it is both hotter and more humid outside than is desired inside. Insulation deals with temp, but not the humidity
@TechConnectify 5. The easy way to deal with humidity is to simply be leaky with A/C. That’s the reason why all the old school home builders insist that structures must breathe. But you can’t both be leaky and efficient.
In my climate, eliminating the existence of the unconditioned attic is the most effective way of both increasing cooling efficiency and dealing with humidity.
A hot and dry environment likely has a different ideal construction.
@TechConnectify 6. A cold environment is by definition different, as any leaking incoming air is almost ensured to be drier when heated to desirable temps than the air inside. So yes, you don’t have R50 in your walls, but you might in your ceiling. I also don’t have R50 in my walls because a simple overhang protects my walls from solar load, but R50 in the attic doesn’t fix the problem that I either have a 150F+ attic with a bad vapor barrier or I have an actively vented attic.
@TechConnectify 7. An actively vented attic for me could ensure that the attic is only 120F instead of 150F, but it doesn’t deal with the humidity. And thus we get back to making the roof deck the barrier to the outside rather than the ceiling.
Observe your attic. How would you seal off all airflow above your insulation around the roof trusses?
@TechConnectify 8. Of course, as you know, wood absorbs water. Imagine each of those trusses acting as a slow wick for thirty years. This is why the attic itself is bad here, and why your insistence that we can insulate our way out of it is both stupid but has been shown to be false for longer than you have been alive.
@transcendentape I'm about to release a video today but before this gets lost in the shuffle I wanted to reply.
Firstly, I understand what you mean and will admit I wasn't considering the nuances of the vapor barrier. However, I still feel like you're missing something.
Granted, what I'm about to suggest may not be "normal" construction. But that's really what I'm trying to do, here! Challenge some norms.
Let's start with a baseline:
@transcendentape The roof has pitch to shed water. That's why it's there, and the negative space creates the attic.
Now, let's agree that we're not using the attic space in any way which truly requires it to be conditioned.
With that in mind, I'd like to circle back to your assertion that it's easy to insulate a wall, but harder the ceiling. What if you simply built the ceiling like a wall? Like a really thick wall. Same techniques, but sitting on top of the other walls making a big box.
@transcendentape Not just some drywall with cellulose on top, but a proper enclosure with sufficient vapor barrier. Like a home with a flat roof.
Flat roofs are cool, but also have some downsides so you decide to put a hat on this flat-roofed house and that's now the attic.
Do we agree that that sort of home could be built? I'm not making any conjecture about cost-effectiveness, here - just that it could be done in your climate.
@transcendentape Because if the answer is yes, I question the value of conditioning that attic space at all. It's a lot more air volume, the insulation will be in direct contact with the hot AF roof structure, and surely those factors increase the total thermal load.
And if you add forced ventilation to that attic space when the sun's up, you'll decrease the temperature gradient the insulation is fighting against.
@transcendentape Treating the attic solely as a structure to frame the roof, letting it breathe, and keeping it entirely thermally (and... vaporly?) separated from the conditioned part of the structure doesn't seem any different to me than the realities prior to the advent of cooling. You just have old-tech above the living space and new-tech within it.
But, I'll grant you right out of the gate that there may very well be other factors I'm not considering.