The "Hot Upstairs" Topic

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sureshoe
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The "Hot Upstairs" Topic

Post by sureshoe »

This topic is scattered throughout the internet and these forums. I have personally dealt with it for the last 20 years in different forms and homes. I'm going to make some decisions in my current home (which I've been at for 3 years now).

Classic problem: I have a 20 year old house that is 5500+ square feet if you include the basement. There are 3 bedrooms upstairs that are each roughly 12x12. And of course, they stay hot all summer. I can have the first floor thermostat down to 70 degrees, and it will still be almost 80 degrees upstairs. Many of the houses in our neighborhood have a 2nd unit upstairs in a closet. Ours just doesn't happen to have that.

I've done all the generic solutions you find online: I run the fan, I've opened/closed vents, all rooms and hallways upstairs have returns, we have blackout shades, I clean my filter, etc. Nothing makes a meaningful difference (as expected).

That pretty much only leaves a couple options:
A) Have the ducts inspected/sealed/cleaned. I'm not opposed to this, but I imagine it won't help. If someone is really passionate about this and can actually give examples where it made a real difference, I'm open to hearing it - but I think I'm fighting physics here, not a leaky/dirty duct.

B) As a followup to A), maybe see if we can run additional ducts. I'm not super keen on this because it would involve tearing open walls/etc. and I'm not 100% sure it actually solves the problem - unless maybe coupling it with a stronger unit downstairs. I know someone who did this, but it was in a much smaller, older house that didn't have returns on the 2nd floor. It made a dramatic difference - I don't think it would in my case.

C) Install a full, second HVAC in the attic. I've gotten 2 quotes on this from people I've asked to look. The total cost is around $14-$18k with electrical/etc. I know for a fact this would solve the problem, but I want to be sure it doesn't create new problems. Putting a unit up in the attic makes me nervous, but they swear it would be insulated, not leak, etc. Also, it's a bit pricey, but I can live with that.

D) I'm sniffing around at multi-zone minisplit like this:
https://www.alpinehomeair.com/product/a ... gIQAvD_BwE
I have a wall unit in my garage, which is awesome - but we don't want 3 air handlers installed. I love the idea of the ceiling install. Both people I had out to look at my setup scoffed at the minisplit and said "do the HVAC in the attic."
This is my preferred option based on price - $3000-$5000 for the unit, hopefully no more than $2000-$4000 for installation, and hopefully very efficient. But, I have no idea if this is practical.

OK - so thanks for reading if you got this far. Questions for this group: Do you have a recommendation for a durable, real fix - either A, B, C, D above or option E?

I'm looking for a real fix, not half measures. If $20k is what it will take, I'll pay it - but I don't' want to just cut that check without being more informed.
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happysteward
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Re: The "Hot Upstairs" Topic

Post by happysteward »

Can you feel air exiting from the rooms in the returns upstairs? To be more quantitative you could purchase a digital anemometer and measure the flows on the supply’s and returns, I did this at my daughters house and it helped me understand what was going on, some of the ducts at the far points of the house were too small and restricting air flow.
Last edited by happysteward on Wed Jan 03, 2024 1:34 pm, edited 1 time in total.
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dukeblue219
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Re: The "Hot Upstairs" Topic

Post by dukeblue219 »

How well insulated is the upstairs from the attic above it? That might be another attack vector...
Chadnudj
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Re: The "Hot Upstairs" Topic

Post by Chadnudj »

dukeblue219 wrote: Wed Jan 03, 2024 1:29 pm How well insulated is the upstairs from the attic above it? That might be another attack vector...
Yeah, I'd have a home audit done by a reputable company to see where heat (and/or cool) is leaving the house. Ours revealed significant insulation problems (lack of any internal wall insulation all the way up to the attic, meaning heat went into interior walls and then right up and out the attic, for one; other portions of the house that were uninsulated; the basement needed resealing; and we didn't have enough insulation in the attic) that, once fixed, made my house FAR less drafty in winter, FAR cooler in summer, and saved me around 10-15% on my electric/gas bill.
jayjayc
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Re: The "Hot Upstairs" Topic

Post by jayjayc »

The summer sun is baking your attic. That heat transfers down to your upstairs rooms. Find a way to ventilate your attic so heat can escape. Easy test would be to go into your attic at 3pm and see if it feels like a dry sauna that'll melt your face. Ridge vents, whirlybirds, fans, etc.
Mr. Rumples
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Re: The "Hot Upstairs" Topic

Post by Mr. Rumples »

More and more folks seem to use mini-splits; don't know if they are more aesthetically pleasing.

My HVAC is in the attic and while the HVAC folks say it's OK, it gets awfully hot up there. One person I know had "attic foil" installed; it helped. My roofer said don't use foam between rafters, didn't ask about foil, but it appears foil can be put on top of insulation between ceiling joists or up between rafters. https://www.energy.gov/energysaver/radiant-barriers

Some older homes I have been to have high velocity AC which reduces the amount of work and mess.

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tyrion
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Re: The "Hot Upstairs" Topic

Post by tyrion »

I did the minisplit install for a similar issue. 2150 sq ft, no issues keeping the downstairs nice and cool but it gets warm upstairs in the afternoons. Only return air was downstairs. Not a lot of luck trying to equalize temps with fans blowing air between the 2 floors, and the attic is warm but well ventilated and reasonably insulated.

I put in a single minisplit for the master which is about half of the upstairs, with 2 smaller bedrooms being the other half. It's perfect for keeping the master cool, and for now it does enough for the other upstairs bedrooms (along with the whole house AC). The kids will both be off at college in 2 years so I didn't bother with a multi zone solution.

I opted for just one wall unit for both efficiency and ease of install. The way it's installed all connections are external and drain with gravity so minimal chance of water leaks. The cassette units use a small condensation pump to get rid of water.

I may end up putting another minisplit in depending on future use cases for the upstairs bedrooms, and we do have a portable AC unit we can hook up to cool the hotter of the 2 smaller upstairs bedrooms.
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Re: The "Hot Upstairs" Topic

Post by Chadnudj »

Mr. Rumples wrote: Wed Jan 03, 2024 1:36 pm More and more folks seem to use mini-splits; don't know if they are more aesthetically pleasing.

My HVAC is in the attic and while the HVAC folks say it's OK, it gets awfully hot up there. One person I know had "attic foil" installed; it helped. My roofer said don't use foam between rafters, didn't ask about foil, but it appears foil can be put on top of insulation between ceiling joists or up between rafters. https://www.energy.gov/energysaver/radiant-barriers

Some older homes I have been to have high velocity AC which reduces the amount of work and mess.

https://thecraftsmanblog.com/what-is-hi ... ditioning/
You could also invest in a whole house fan/attic fan, that might force out some of the heat in the summer.
wilked
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Re: The "Hot Upstairs" Topic

Post by wilked »

Make a layout of your second floor, with North marked, and post it, noting the “problem children” rooms.

Do you have access to the attic above these rooms? Have you inspected the insulation? What type / thickness of insulation do you have?
thedaybeforetoday
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Re: The "Hot Upstairs" Topic

Post by thedaybeforetoday »

I'm seeing mini split a/c, 3 units, one for each bedroom, for $4k.
Is this a viable option that solves the issue? More efficient than an entire second unit for the entire upstairs.
May wish to combine with, or just start with, an attic fan. Those are only a few hundred bucks.
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ETK517
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Re: The "Hot Upstairs" Topic

Post by ETK517 »

You almost certainly have a poorly insulated and/or unventilated attic.
mw1739
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Re: The "Hot Upstairs" Topic

Post by mw1739 »

We added the second HVAC unit and it's helped tremendously. 10 years in and no issues. With that said, I know the minisplit technology has advanced quite a bit and I would be pretty interested in that if I was doing it all over again.
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Re: The "Hot Upstairs" Topic

Post by 02nz »

Having you tried closing some of the downstairs rooms' vents in summer? That would mean less cool air going downstairs and should give you a more consistent temperature between downstairs and upstairs.
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id0ntkn0wjack
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Re: The "Hot Upstairs" Topic

Post by id0ntkn0wjack »

sureshoe wrote: Wed Jan 03, 2024 1:21 pm
I'm looking for a real fix, not half measures. If $20k is what it will take, I'll pay it - but I don't' want to just cut that check without being more informed.
I highly recommend that you get an Energy Audit by a certified (HERS?) inspector who will run a blower door test and perform an IR scan. While there's a chance that your HVAC is improperly balanced, it's far more likely that air sealing/insulation installation is suspect in which case throwing BTUs at the problem will be an expensive solution.
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id0ntkn0wjack
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Re: The "Hot Upstairs" Topic

Post by id0ntkn0wjack »

Chadnudj wrote: Wed Jan 03, 2024 2:29 pm

You could also invest in a whole house fan/attic fan, that might force out some of the heat in the summer.
This is terrible advice: https://www.energyvanguard.com/blog/is- ... entilator/
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Re: The "Hot Upstairs" Topic

Post by a.s.r »

We did Mitsubishi ductless units for a similar issue (https://www.mitsubishicomfort.com/resid ... odelID=MLZ) - but we have radiator heat so didn't already have ductwork. If you look further at this option, Wirecutter recommends going with one of the leading brands for repair/maintenance purposes, so I'd at least quote out some of them: Mitsubishi, LG, Daikin, Panasonic (https://www.nytimes.com/wirecutter/revi ... nditioner/). I'd probably trust the experts you had out to look and go with the attic HVAC, although if you had folks come who were not authorized installers for mini-split systems they may have been incentivized to discount that option.
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lthenderson
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Re: The "Hot Upstairs" Topic

Post by lthenderson »

Like others, I would verify insulation in walls and attic. My second attempt would be to invest in smart vent covers that work with your smart thermostat. They adjust continuously to direct cold air where needed the most.
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Re: The "Hot Upstairs" Topic

Post by adamthesmythe »

I do OP the courtesy of assuming that there are no obvious problems with insulation and sealing, and that he is fighting the problem that heat rises.

It is possible that some sort of rebalancing or other adjustments to the vents will have enough of an impact. If this does not work, the choices are minisplit or a conventional second HVAC unit.

Conventional is probably less efficient in terms of cooling per watt consumed (based on comments about minisplits).

Minisplits are probably less aesthetic and may cost more when installed by a contractor. I have also seen complaints about sensitivity of the electronics to power surges.

You pays yer money and you makes yer choice.
talzara
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Re: The "Hot Upstairs" Topic

Post by talzara »

sureshoe wrote: Wed Jan 03, 2024 1:21 pm D) I'm sniffing around at multi-zone minisplit like this:
https://www.alpinehomeair.com/product/a ... gIQAvD_BwE
That is an R-410A white label unit. Even if you can figure out which company manufactured the unit, you're going to have trouble getting parts later. They're going to be discontinued as they switch to other refrigerants.

An R-410A mini-split from a name brand might still have parts in 10 years, but parts for white label units will be discontinued more quickly.
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Re: The "Hot Upstairs" Topic

Post by talzara »

adamthesmythe wrote: Wed Jan 03, 2024 5:41 pm I do OP the courtesy of assuming that there are no obvious problems with insulation and sealing, and that he is fighting the problem that heat rises.
That is usually an incorrect assumption.

Most houses in the United States have problems with air-sealing. Most general contractors do not do blower door tests on their houses, so you don't know how bad the air leaks are. Building inspectors will check for the presence of insulation, but air leaks are hidden.

In summer, a hot second floor is usually not caused by hot air rising. If the temperature differential is lower on an overcast day, it usually means the heat is coming from the roof or the attic. That is why insulation, air sealing, and radiant barriers are important.
Carl53
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Re: The "Hot Upstairs" Topic

Post by Carl53 »

Owned a 130 year old two story (upstairs is about 60% of downstairs) for three years. In summer the upstairs was unacceptable, at least 10 degrees hotter than first floor. We replaced the ancient windows and added a near ceiling return in the upstairs hall (previously none in the upstairs). Yes, we did rip open some walls to get a return upstairs but it was worth it. Now the upstairs is within a degree or two of the downstairs. Oh we did add ceiling fans to the 2nd floor bedrooms but seldom turn them on unless for a special need.
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Re: The "Hot Upstairs" Topic

Post by Johnny Thinwallet »

We also had "hot upstairs" issues when we bought our house. And since I can't sleep in a hot room it would force to turn the thermostat way down in the evening just to cool the upstairs enough to sleep.

The problem turned out to be subpar attic insulation. The best areas were R30. But two areas had zero insulation, including an attic knee wall along our master bedroom that had nothing but a 5x5 spot of uninsulated drywall separating the bedroom to the attic. In other areas the 10ish inches of insulation was compressed down to 4 or 5 inches due to contractors walking around doing work on previous projects.

Two years ago we addressed the attic insulation. R60 now everywhere, radiant barriers installed, soffit ventilation improved, gaps filled in, knee wall addressed. It's now cooler upstairs in the dog days of summer than it is on our main level.
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Re: The "Hot Upstairs" Topic

Post by Random Musings »

jayjayc wrote: Wed Jan 03, 2024 1:34 pm The summer sun is baking your attic. That heat transfers down to your upstairs rooms. Find a way to ventilate your attic so heat can escape. Easy test would be to go into your attic at 3pm and see if it feels like a dry sauna that'll melt your face. Ridge vents, whirlybirds, fans, etc.
This. After about 4 years in our current house, a friend and myself put in attic storage as well as installing an attic fan. The temperature differential between the first and second floor was substantially reduced.

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Re: The "Hot Upstairs" Topic

Post by thebeerbarron »

Assuming your current HVAC is adequately sized, I would look into air sealing and adding attic insulation. Attic temps can easily get above 120 degrees in summer and all that heat is radiating back into the house. Similarly, if not properly air sealed all of your cold conditioned air will escape to the warm attic so throwing more cold air at it wont really help you. As others have recommended I'd suggest getting an energy audit. You may also want to check out your local library to see if they have something like a Flir thermal camera which can show any hot spots in your ceiling.
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Re: The "Hot Upstairs" Topic

Post by ScubaHogg »

More attic insulation is the obvious first step
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Re: The "Hot Upstairs" Topic

Post by snic »

id0ntkn0wjack wrote: Wed Jan 03, 2024 3:16 pm
Chadnudj wrote: Wed Jan 03, 2024 2:29 pm

You could also invest in a whole house fan/attic fan, that might force out some of the heat in the summer.
This is terrible advice: https://www.energyvanguard.com/blog/is- ... entilator/
A whole house fan is not necessarily terrible advice. It depends on the OP's climate, and actually WWFs can be used in more climates than they're now used in. The basic idea is that if it gets cool enough in the evening that it's pleasant outside, you turn off your a/c, crack your windows open, and turn on the WWF. It draws cool air into the house, pushes it from there into the attic, and from the attic it's vented to the outside. So (a) you cool your house down, quite quickly from my experience seeing this work in California and Oregon; (b) you cool your attic down, and (c) your house stays cooler for longer the next day, so you can delay turning your a/c on. This could conceivably make a big difference to the OP's hot-upstairs problem.

That said, I second the suggestions to get an energy audit, including a blower door test to look for air leaks, before making any decisions. If there are insulation or air leakage problems, adding a powerful new a/c will still work, but you will be paying to air condition the outdoors. Air sealing and insulation might not solve the hot-upstairs problem, but it could allow you to get away with a less powerful (fewer BTUs/hr) and therefore less expensive a/c system.

I don't know much about mini-splits, but I do know they're used all over the world - where energy prices tend to be higher than here - because they are very energy efficient. There is a growing trend to use them here. Take what HVAC contractors say about them with a big grain of salt. They are used to installing central a/c's, and if they don't install mini-splits, of course they are going to push you towards their own products. Find a contractor that specializes in mini-splits and you'll hear something different. Finally, don't forget to look into tax credits you could get for installing energy-efficient HVAC systems, as well as state and utility incentives.
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sureshoe
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Re: The "Hot Upstairs" Topic

Post by sureshoe »

happysteward wrote: Wed Jan 03, 2024 1:27 pm Can you feel air exiting from the rooms in the returns upstairs? To be more quantitative you could purchase a digital anemometer and measure the flows on the supply’s and returns, I did this at my daughters house and it helped me understand what was going on, some of the ducts at the far points of the house were too small and restricting air flow.
I think there is airflow. The question becomes "is it enough", so the anemometer is one idea. Other folks have mentioned a infrared thermometer.
Chadnudj wrote: Wed Jan 03, 2024 1:33 pm
dukeblue219 wrote: Wed Jan 03, 2024 1:29 pm How well insulated is the upstairs from the attic above it? That might be another attack vector...
Yeah, I'd have a home audit done by a reputable company to see where heat (and/or cool) is leaving the house. Ours revealed significant insulation problems (lack of any internal wall insulation all the way up to the attic, meaning heat went into interior walls and then right up and out the attic, for one; other portions of the house that were uninsulated; the basement needed resealing; and we didn't have enough insulation in the attic) that, once fixed, made my house FAR less drafty in winter, FAR cooler in summer, and saved me around 10-15% on my electric/gas bill.
jayjayc wrote: Wed Jan 03, 2024 1:34 pm The summer sun is baking your attic. That heat transfers down to your upstairs rooms. Find a way to ventilate your attic so heat can escape. Easy test would be to go into your attic at 3pm and see if it feels like a dry sauna that'll melt your face. Ridge vents, whirlybirds, fans, etc.
So I'll probably pull the trigger on an energy audit. I'm not convinced it will help, but for a couple hundred bucks, it's can't hurt too much. If we can fix the problem with a few hundred bucks, I'd love to be proven wrong.

Parsing thru the other discussions on here, good stuff.
tortoise84
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Re: The "Hot Upstairs" Topic

Post by tortoise84 »

Would you consider window ACs? I bought three Midea 8,000 BTU U-shaped window ACs for my house and my parents' house. They are very quiet and efficient because they have variable speed inverter driven compressors. In fact, they are so efficient that I use them instead of my central AC and reduced my electricity usage by 13%: viewtopic.php?t=399895

Midea 10,000 BTU U-shaped AC for $319: https://www.amazon.com/dp/B0866Y33PL/

Midea 12,000 BTU (non-U) window AC with heat pump (only works >41F) for $499: https://www.amazon.com/dp/B0B3NJGSKL/
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sureshoe
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Re: The "Hot Upstairs" Topic

Post by sureshoe »

Mr. Rumples wrote: Wed Jan 03, 2024 1:36 pm More and more folks seem to use mini-splits; don't know if they are more aesthetically pleasing.

My HVAC is in the attic and while the HVAC folks say it's OK, it gets awfully hot up there. One person I know had "attic foil" installed; it helped. My roofer said don't use foam between rafters, didn't ask about foil, but it appears foil can be put on top of insulation between ceiling joists or up between rafters. https://www.energy.gov/energysaver/radiant-barriers

Some older homes I have been to have high velocity AC which reduces the amount of work and mess.

https://thecraftsmanblog.com/what-is-hi ... ditioning/
Thanks for the links. For the radiant barrier, it seems to suggest it's better for hot weather climates - I'm in Ohio, but like I posted above, I guess I'll get an energy audit done to see what they think and whether that's the best option.

The high velocity AC is interesting as an alternative to a traditional HVAC or minisplit. Will explore that, but guessing even with the small tubes, it would be quite a chore to run tubes to it.
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sureshoe
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Re: The "Hot Upstairs" Topic

Post by sureshoe »

a.s.r wrote: Wed Jan 03, 2024 3:23 pm We did Mitsubishi ductless units for a similar issue (https://www.mitsubishicomfort.com/resid ... odelID=MLZ) - but we have radiator heat so didn't already have ductwork. If you look further at this option, Wirecutter recommends going with one of the leading brands for repair/maintenance purposes, so I'd at least quote out some of them: Mitsubishi, LG, Daikin, Panasonic (https://www.nytimes.com/wirecutter/revi ... nditioner/). I'd probably trust the experts you had out to look and go with the attic HVAC, although if you had folks come who were not authorized installers for mini-split systems they may have been incentivized to discount that option.
Cool - so you did the ceiling cassette?

This is where I'm going back and forth. The guys are suggesting the HVAC in the attic, but it is a pretty big sledgehammer. I love the minisplit in the garage, but this is a different use case.
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sureshoe
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Re: The "Hot Upstairs" Topic

Post by sureshoe »

lthenderson wrote: Wed Jan 03, 2024 5:11 pm Like others, I would verify insulation in walls and attic. My second attempt would be to invest in smart vent covers that work with your smart thermostat. They adjust continuously to direct cold air where needed the most.
Do you know anyone who used the vent covers. I gave them a shot and they're absolutely worthless. Fundamentally, you can't pull more air through a system than it is designed to do.
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sureshoe
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Re: The "Hot Upstairs" Topic

Post by sureshoe »

talzara wrote: Wed Jan 03, 2024 5:45 pm
sureshoe wrote: Wed Jan 03, 2024 1:21 pm D) I'm sniffing around at multi-zone minisplit like this:
https://www.alpinehomeair.com/product/a ... gIQAvD_BwE
That is an R-410A white label unit. Even if you can figure out which company manufactured the unit, you're going to have trouble getting parts later. They're going to be discontinued as they switch to other refrigerants.

An R-410A mini-split from a name brand might still have parts in 10 years, but parts for white label units will be discontinued more quickly.
Thanks a lot for the comment, I hadn't put a ton of thought into that, and someone else mentioned using an LG or Mitsubishi or whatever. Right now, I need to land on whether or not to do the minisplit :)
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Re: The "Hot Upstairs" Topic

Post by firebirdparts »

I have an older cape cod, so that means I have a much worse situation than a real 2 story house. Much worse. I put a second unit upstairs, but I enjoy building ductwork, so it wasn't really an imposition on me. A friend of mine who lived in an even older cape cod told me that he ran a second hot air return to the 2nd floor and they ran that exclusively in summer, and that really solved it for him. So that is very much superior financially to the options you listed, if it works.

so they blocked off one of their returns depending on the season.
This time is the same
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Re: The "Hot Upstairs" Topic

Post by wilked »

Sureshoe, I didn't see a response - have you personally evaluated the insulation in the attic?
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Re: The "Hot Upstairs" Topic

Post by Cody »

My daughters condo has 20 foot ceilings and an open stairwell to upstairs (no door). We tried practically everything to keep the upstairs and downstairs tempurature about the same.

Finally we installed a DC current, big blade fan. It is a game changer. The DC current model allows it to run 24-7.

Is it perfect - no. Is it better - greatly so.

Think about how much better you want the heat situation and be realistic - would a 50% improvement do for you?

We found there was no magic bullet but did the fan and some vent adjustment and are satisfied.

Best
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Re: The "Hot Upstairs" Topic

Post by clutchied »

sureshoe wrote: Wed Jan 03, 2024 1:21 pm

OK - so thanks for reading if you got this far. Questions for this group: Do you have a recommendation for a durable, real fix - either A, B, C, D above or option E?

I'm looking for a real fix, not half measures. If $20k is what it will take, I'll pay it - but I don't' want to just cut that check without being more informed.

I'm in a similar circumstance 4900 sq. ft. 3 beds upstairs. I have a solid 15 degree differential b/w the basement and upstairs. We have BIG West facing windows that just suck up heat in the summer. Single zone 5 ton unit from 1989.


We've done 2 things so far. 1. We put R60 in the attic. The effect was that the A/C could actually keep up during the heat of the day and we didn't lose ground. 2. We tested a new window in the hottest part of the house and it appears that there was very little insulation in there and we were getting tons of heat penetration through the wall.... weird. I wish I was there during install b/c the wall heat dropped 15+ degrees around the window so they did something and the window works better now...

Our 3rd step will be to install a mini split in upstairs hallway to take some of the load off.


So we have concrete wins currently but the problem persists but we are on the right path. I also considered the ceiling cassette in each room but I put in the insulation first and I don't want to mess with it anymore...
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Re: The "Hot Upstairs" Topic

Post by lthenderson »

sureshoe wrote: Thu Jan 04, 2024 8:10 am
lthenderson wrote: Wed Jan 03, 2024 5:11 pm Like others, I would verify insulation in walls and attic. My second attempt would be to invest in smart vent covers that work with your smart thermostat. They adjust continuously to direct cold air where needed the most.
Do you know anyone who used the vent covers. I gave them a shot and they're absolutely worthless. Fundamentally, you can't pull more air through a system than it is designed to do.
I haven't used them personally. They were used on an "Ask This Old House" episode for someone complaining of the same issue. They don't "pull more air through" but do real time adjustments that aren't practical for a homeowner. But it sounds like they didn't work for you which makes me suspect you have larger issues, such as inadequate insulation.
iamlucky13
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Re: The "Hot Upstairs" Topic

Post by iamlucky13 »

Our house has seriously undersized ducting to the 2nd floor, and no easy way to add more ducting.

This is not as effective as a minisplit would be, it won't work in the more humid regions where it doesn't cool off much overnight, and it takes a couple minutes each day, but its far cheaper:

We open the upstairs windows as soon as the outside temperature falls below the upstairs temperature in the evening, and run fans in the windows until it is cool enough. On the hottest days, we run the fans all night, and shut the windows again in the morning when the outside temperature again exceeds the upstairs temperature.

Our attic is fairly well insulated, and with the blinds closed on all south-facing windows, the upstairs then stays reasonably comfortable on all but the hottest days.

On the hottest days, we have tried positioning a fan blowing down the stairs to circulate cooled air from the first floor, as well as just running the HVAC system in fan only mode once the air conditioning has the downstairs cool enough. These aren't particularly effective methods, but they do help.

It would be intrusive, but since it would only be needed for us a few days a year, I have considered getting a blower fan than can be used with collapsible flex duct to more effectively move the air between floors. They're a little more expensive than I expected, and I suspect also rather noisy:

https://www.homedepot.com/p/Maxx-Air-8- ... /202794278

I've also considered just installing one of the Mr. Cool ductless minisplits (a DIY-oriented brand). This would also require figuring out how squeeze another breaker into our panel and a route for the wiring to the location. This should be doable, and is stuff the contractor should handle if hiring it out, but that's not in our budget.
edge
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Re: The "Hot Upstairs" Topic

Post by edge »

It actually isn't and it depends on the nature of the problem. If the cool airflow to the second floor is very poor then adding additional attic insulation will keep the hot air in versus a leaky attic where it could at least escape. It is a tricky problem that may require mutiple solutions.
ScubaHogg wrote: Wed Jan 03, 2024 11:52 pm More attic insulation is the obvious first step
protagonist
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Re: The "Hot Upstairs" Topic

Post by protagonist »

A 10 degree difference seems unusually huge. We have a 2 story Victorian (vintage 1884) farmhouse with an attic, with two heating zones (upstairs and downstairs), and the diff. is rarely more than a couple of degrees.
Is your downstairs very shaded while your upstairs is exposed to direct sun? That will make a huge difference. I seriously question whether insulation and efficient windows would compensate- maybe shutters would. I have a window AC unit in a particularly exposed upstairs room in the summer.

We winter in Florida. The difference this month between our balcony temperature (direct sun) and our catwalk temperature (completely shaded and windy) is often a whopping 30-45 degrees. For example, yesterday, when the high temp. was 69 acc. to the weather service, I was seeing 103 in the direct sun and 60 on the catwalk. And I have put a temp. sensor right by a sunny window in the summer in our New England Victorian and gotten readings mid-day well over 110 degrees when the house otherwise does not seem hot because the house is otherwise well shaded. You can tell just by touching a window.
Last edited by protagonist on Thu Jan 04, 2024 11:47 am, edited 5 times in total.
bloom2708
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Re: The "Hot Upstairs" Topic

Post by bloom2708 »

I have battled this for 19 years in our current house. 2 story with full basement.

When both cold and windy, the upstairs still gets too warm in the winter at times.

My best solution has been to tolerate lower temps. I keep the furnace at 68 or 69 when home. I turn down to 66-67 at night.

My ecobee has 4 remote sensors and I use the upstairs and one main floor to temp average. I run the fan zero minutes each hour. I have the ecobee savings setting at max 20%. It detects when nobody is home. It allows the temps to be slightly lower and not run the furnace at times.

With closing vents on the top floor, this keeps our upstairs from getting too warm. Mostly for my wife as she cannot sleep if too warm.

These are all just lipstick on a pig. 3rd kid graduates in 2 years and then we will right size to a house with one level above ground.
mrc
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Re: The "Hot Upstairs" Topic

Post by mrc »

This is a perfect illustration of Roger Pressman's (software engineering) adage: "Are we solving the right problem, and are we solving the problem right?"

My two story mid-80s colonial house is half the size of yours, with one central ducted HVAC plant. Every tech that's been here for 20 years says houses like this generally have two plants, including a dedicated unit for the upstairs. I should add, the rear of the house (with most of the glass) faces southwest. The second story ducts are in the ceiling, and run through an unconditioned attic. Oh, they are flexible ducts. It is humid here. Cold air is heavy, and there is no way the fan can push air up three floors, across a hot attic, through too-small flex ducts, and adequately cool the second floor. The cherry on top is a central return in the hall. If you shut a bedroom door, you have near zero airflow.

I installed a mini split with one head in the master bedroom. The other two bedrooms remain hot, but no one is in them. The next owner would likely have to install a third spit or a window unit to make that southwest bedroom habitable, but that's not my problem.

The split made all the difference in the world and solve the problem 100%. It's paying for itself over time because I was able to raise the A/C thermostat by 7 degrees. I had lowered it in a vain attempt to mange the upstairs heat. Some units use ceiling cassettes (no big box on the wall) and can feed multiple rooms.

Good luck identifying and solving your problem.
By the time you know enough to choose a good financial adviser, you don't need one. | bogleheads.org is my advisor: The ER is 0.0% and the advice always solid.
Topic Author
sureshoe
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Re: The "Hot Upstairs" Topic

Post by sureshoe »

wilked wrote: Thu Jan 04, 2024 8:37 am Sureshoe, I didn't see a response - have you personally evaluated the insulation in the attic?
So I sorta generically replied that I'm going to do a home energy audit.

I had looked at it before, and maybe was misremembering it as "better":
Image
Image

Calling a "reputable" company is a bit tricky - the DOE site doesn't really have anything near. I found 1-2 local contractors I'm going to check with, but one of them was basically "hey, install solar", so I'm just super skeptical by nature.

So looking at the picture, the insulation is not perfect. 10-14 inches in some places, valleys that are near to wood in others.

I have a company coming out next week who are going to do a free look. They say they can do blower tests/etc, but will give me a 30 minute look/estimate for fixes. The guy on the phone said insulation typically settles/wears out after 20 years and I'm on the cusp of that. Additionally, I have checked garage, which is adjacent to one of the rooms. They have a standard pacakge of insulation between the joists, so I'm assuming that garage is a furnace and contributing.

So at a minimum, I'm guessing $1-$3k of insulation work needs done, and whether I do a minisplit/unit later - that work will pay for itself over a year or two.
FeralCat
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Re: The "Hot Upstairs" Topic

Post by FeralCat »

iamlucky13 wrote: Thu Jan 04, 2024 10:39 am Our house has seriously undersized ducting to the 2nd floor, and no easy way to add more ducting.

This is not as effective as a minisplit would be, it won't work in the more humid regions where it doesn't cool off much overnight, and it takes a couple minutes each day, but its far cheaper:

We open the upstairs windows as soon as the outside temperature falls below the upstairs temperature in the evening, and run fans in the windows until it is cool enough. On the hottest days, we run the fans all night, and shut the windows again in the morning when the outside temperature again exceeds the upstairs temperature.

Our attic is fairly well insulated, and with the blinds closed on all south-facing windows, the upstairs then stays reasonably comfortable on all but the hottest days.

On the hottest days, we have tried positioning a fan blowing down the stairs to circulate cooled air from the first floor, as well as just running the HVAC system in fan only mode once the air conditioning has the downstairs cool enough. These aren't particularly effective methods, but they do help.

It would be intrusive, but since it would only be needed for us a few days a year, I have considered getting a blower fan than can be used with collapsible flex duct to more effectively move the air between floors. They're a little more expensive than I expected, and I suspect also rather noisy:

https://www.homedepot.com/p/Maxx-Air-8- ... /202794278

I've also considered just installing one of the Mr. Cool ductless minisplits (a DIY-oriented brand). This would also require figuring out how squeeze another breaker into our panel and a route for the wiring to the location. This should be doable, and is stuff the contractor should handle if hiring it out, but that's not in our budget.
Last summer I was without AC for a month (they had to wait for a part to repair the central AC). I then discovered the incredible beauty of window fans - something people used to use a long time ago before AC. I had two window box fans on the main level pulling in cooler night air, and three fans on the second floor pushing out hot indoor air. On days when the high was around 95F and humid, low 72F overnight - without the fans I would wake up at 6 am and my house would be about 92F still. With the fans I would wake up freezing and the house would be about 72F. Using this system to cool the house in the evening isn't as simple as turning on the AC. But it works.
Barefoot
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Re: The "Hot Upstairs" Topic

Post by Barefoot »

When I was a kid, my Dad would put saran wrap over the downstairs return during the summer months. This forced the A/C to suck all return air from upstairs and it kept the temps upstairs pretty much the same as downstairs.

Cost was less than a buck.
mrc
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Re: The "Hot Upstairs" Topic

Post by mrc »

Barefoot wrote: Thu Jan 04, 2024 1:52 pm When I was a kid, my Dad would put saran wrap over the downstairs return during the summer months. This forced the A/C to suck all return air from upstairs and it kept the temps upstairs pretty much the same as downstairs.

Cost was less than a buck.
You run a risk of impeding airflow across the evaporator coil and freezing it up. It's the hot air passing over the coil that prevents freeze ups.
By the time you know enough to choose a good financial adviser, you don't need one. | bogleheads.org is my advisor: The ER is 0.0% and the advice always solid.
mrc
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Re: The "Hot Upstairs" Topic

Post by mrc »

FeralCat wrote: Thu Jan 04, 2024 1:27 pm
Last summer I was without AC for a month (they had to wait for a part to repair the central AC). I then discovered the incredible beauty of window fans - something people used to use a long time ago before AC. I had two window box fans on the main level pulling in cooler night air, and three fans on the second floor pushing out hot indoor air. On days when the high was around 95F and humid, low 72F overnight - without the fans I would wake up at 6 am and my house would be about 92F still. With the fans I would wake up freezing and the house would be about 72F. Using this system to cool the house in the evening isn't as simple as turning on the AC. But it works.
That worked pretty well for us in Ann Arbor, MI for all but about two weeks of the summer. But here in metro DC, no way. The humidity is a constant problem (except for about the same 14 days of the year, but spread out over spring and fall).
By the time you know enough to choose a good financial adviser, you don't need one. | bogleheads.org is my advisor: The ER is 0.0% and the advice always solid.
ekid
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Re: The "Hot Upstairs" Topic

Post by ekid »

sureshoe wrote: Thu Jan 04, 2024 11:53 am
wilked wrote: Thu Jan 04, 2024 8:37 am Sureshoe, I didn't see a response - have you personally evaluated the insulation in the attic?
So I sorta generically replied that I'm going to do a home energy audit.

I had looked at it before, and maybe was misremembering it as "better":
Image
Image

Calling a "reputable" company is a bit tricky - the DOE site doesn't really have anything near. I found 1-2 local contractors I'm going to check with, but one of them was basically "hey, install solar", so I'm just super skeptical by nature.

So looking at the picture, the insulation is not perfect. 10-14 inches in some places, valleys that are near to wood in others.

I have a company coming out next week who are going to do a free look. They say they can do blower tests/etc, but will give me a 30 minute look/estimate for fixes. The guy on the phone said insulation typically settles/wears out after 20 years and I'm on the cusp of that. Additionally, I have checked garage, which is adjacent to one of the rooms. They have a standard pacakge of insulation between the joists, so I'm assuming that garage is a furnace and contributing.

So at a minimum, I'm guessing $1-$3k of insulation work needs done, and whether I do a minisplit/unit later - that work will pay for itself over a year or two.
That looks like good insulation but WAY less than enough for zone 5. Er- where is the location of this project again?
talzara
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Re: The "Hot Upstairs" Topic

Post by talzara »

edge wrote: Thu Jan 04, 2024 11:19 am It actually isn't and it depends on the nature of the problem. If the cool airflow to the second floor is very poor then adding additional attic insulation will keep the hot air in versus a leaky attic where it could at least escape. It is a tricky problem that may require mutiple solutions.
ScubaHogg wrote: Wed Jan 03, 2024 11:52 pm More attic insulation is the obvious first step
This is a common misconception that appears a lot on HVAC threads.

In summer, hot air does not rise in your house. Instead, cold air sinks due to the reverse stack effect. The direction of airflow reverses because indoors is cooler than outdoors, which is the opposite of winter.

Since the cold air escapes through your first floor and basement, the pressure differential will pull even hotter air from the attic into the already-hot second floor.

Adding insulation to the attic will not "keep the hot air in versus a leaky attic where it could at least escape." This is because the hot air is not escaping through the leaky attic. It's coming in from the attic.

Also, insulation is not the same thing as air-sealing. To prevent hot air from being pulled from the attic into your house, you need to air-seal the second floor to isolate it from the attic.

There are three types of heat transfer: conduction, convection, and radiation. Insulation reduces conducted heat. Air sealing reduces convection. Radiant barriers reduce radiated heat.
Last edited by talzara on Thu Jan 04, 2024 3:40 pm, edited 1 time in total.
Chadnudj
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Re: The "Hot Upstairs" Topic

Post by Chadnudj »

ekid wrote: Thu Jan 04, 2024 2:27 pm
sureshoe wrote: Thu Jan 04, 2024 11:53 am
wilked wrote: Thu Jan 04, 2024 8:37 am Sureshoe, I didn't see a response - have you personally evaluated the insulation in the attic?
So I sorta generically replied that I'm going to do a home energy audit.

I had looked at it before, and maybe was misremembering it as "better":

Calling a "reputable" company is a bit tricky - the DOE site doesn't really have anything near. I found 1-2 local contractors I'm going to check with, but one of them was basically "hey, install solar", so I'm just super skeptical by nature.

So looking at the picture, the insulation is not perfect. 10-14 inches in some places, valleys that are near to wood in others.

I have a company coming out next week who are going to do a free look. They say they can do blower tests/etc, but will give me a 30 minute look/estimate for fixes. The guy on the phone said insulation typically settles/wears out after 20 years and I'm on the cusp of that. Additionally, I have checked garage, which is adjacent to one of the rooms. They have a standard pacakge of insulation between the joists, so I'm assuming that garage is a furnace and contributing.

So at a minimum, I'm guessing $1-$3k of insulation work needs done, and whether I do a minisplit/unit later - that work will pay for itself over a year or two.
That looks like good insulation but WAY less than enough for zone 5. Er- where is the location of this project again?
I agree it doesn't look disastrous, but just a picture of uneven cellulose insulation in an attic doesn't tell you much about the quality of it at insulating. For instance, how is sealing? Is insulation within/over interior walls or are those not insulated at all? Is the attic door/panel itself covered with a suitable insulation barrier/insulation dome or whatever it's called?

A air blow test/infrared and reputable company doing a full inspection should be able to show you how effective the insulation you have really is, and whether/to what extent it could be improved. And there are (or at least were) tax credits for doing so (on top of the heating/cooling savings you realize).
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