Recent searches
Search options
Administered by:
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 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 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.
@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 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’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.
@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 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 @transcendentape Now you’re making me envious of those with seas of cellulose insulation, and energy-recovery ventilation.
@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?
@TechConnectify @transcendentape my attic has been terraformed into an unlivable living space
@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 I’m there with you, except- in my climate the existence of an attic at all is a problem.
@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 “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 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 At least in my area, there are a great many reasons to be upset with new home builds.
@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!
@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 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 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!