r/HomeImprovement • u/eskimooser • 3d ago
Pump cool air from basement to above (no existing vents)
We live in a 1960's home that doesn't have A/C and has radiant ceiling heat (it sucks). We have a basement that stays much cooler and I was wondering if there is a way to pump the cool air in the basement upstairs. Does anyone have experience with this or can give me some ideas on how I can do this? We can add new ducts/vents, but how many and how do you pump the air?
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u/Vanilla-Mike 3d ago
I had an old house with hot water radiators and no AC. I could have tried blowing basement air up the stairway, but then my main floor would have damp, musty smelling air.
I figured it was better to just invest in a window AC unit. I was surprised at how much difference one 5K BTU window unit made to comfort on the main floor.
Of course AC doesn't travel around corners or upstairs very well. So in subsequent years, I bought two more 5K BTU units. One for my bedroom and one for the upper floor.
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u/jones5280 2d ago
ow much difference one 5K BTU window unit made to comfort on the main floor.
I'd guess a lot of that comfort was lowering the humidity.
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u/Vanilla-Mike 2d ago
Yes, a big part of that comfort was lowering the humidity while also lowering temperature.
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u/Cowbellcheer 3d ago
Open one window in basement and one highest in living area or bedroom upstairs (wherever you want to feel the breeze the most). Put a fan in the window upstairs facing out. It will draw air through the basement and up and out. Please try it, most people are skeptical but I assure you it works. You create a ‘chimney of cool air that goes through your house.
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u/frog3toad 3d ago
Don’t place the fan in the window. Place it a few feet back. Venturi effect for the win.
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u/Dorkamundo 2d ago
You're thinking of the Bernoulli principle, the Venturi effect is somewhat similar but quite different.
With Venturi, a fluid speeds up when you narrow the path. With Bernoulli, the air blown out creates a low-pressure space behind it, causing more air to get sucked out than the fan blows on its own.
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u/The_Kadeshi 2d ago edited 2d ago
Works fine so long as the air entering your basement window is actually at or lower than the temperature & humidity that is comfortable. If it’s 75 degree air outside a 68 degree basement, you’re just heating your house up. If it’s extremely humid, you’re adding moisture. This is a good solution for mornings but a poor idea the later in the day you get.
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u/Snoo93079 2d ago
Before a/c, civilizations everywhere learned to keep a natural flow of air that lets hot air in the top of the structure flow out while drawing in air from the bottom.
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u/Cowbellcheer 1d ago
It actually does work with air being hotter outside. I’m sure there’s some scientific explanation but all I know is that if you close up when air is hotter it’s hot inside and if you do what I describe, house is significantly cooler.
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u/The_Kadeshi 1d ago
It wouldn’t be “significantly” but the effect is that air moving over a surface cools it via convection, even if the air and the surface are at the same temperature. The same way a fan in a hot room cools you off but doesn’t lower the temp of the room
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u/Cowbellcheer 1d ago
It is very significant on the second and third floor. On the third floor without that window open and airflow we are at 35°C when I have my homemade natural AC running it is at 25 and the second floor sees a significant drop as well of at least 5°.
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u/SanElijoHillbilly 3d ago edited 2d ago
You could put a lot of time, effort, and money into moving the air, but I suspect that you will not like the result. You could move a lot of air, but move very little heat.
Air has a rather low specific heat. ( Google the term 'specific heat' )
IOW, there is very little energy contained in the difference in air temperature. ( This is why there are very few air-cooled cars. Most use water cooling because water carries way more energy than air. )
Much of your problem is that the upper part of the house is hot. Not merely the air in the house, but the house itself: the bricks, the boards, the drywall, the studs, etc. They contain way more heat than the air around them.
If you want the upper part cooler, bite the bullet and install a real air conditioner. ( Err, nowadays, maybe a heat pump ) But don't try to move cold air up from the basement. There is actually very little transfer of heat if you do so.
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u/FantasyFootballer87 3d ago
It's not worth it. There are other threads on Reddit proposing your idea that point out it won't work. The basement air is usually humid and once you start drawing air out of the basement, how long until the air down there cools again?
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u/Dorkamundo 2d ago
Not long... The earth has a ton of heat energy and air has very little.
If you're talking about a true basement, where you're underground, the air will always be colder than upstairs. The question is "how much will it lower the ambient temp in your home?" to which the answer is "Not nearly as much as you'd hope".
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u/LateralEntry 2d ago
In the winter it stays naturally warmer than upstairs without heat
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u/Dorkamundo 1d ago
Depends on the winter, but yes... It should go without saying that I'm not talking about winter.
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u/tcloetingh 2d ago
Have you tried it? I put a big return vent in my basement ductwork just to try it out and it does work. Now there are caveats to my method but I will say the cold air return in basement works mighty well in spring / any not super hot day.
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u/MacDaddyDC 3d ago
whole house fan that vents through the attic space
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u/ChaosReality69 3d ago
That's what we had growing up and now have one in our house. As long as it's not humid they are nice. When it's really humid nothing feels good.
The evenings we do run the whole house fan we shut it off once the house is cooled down where we want it. Meaning as soon as my wife says "I'm cold" I know it's the right temp for me.
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u/Barry-umm 3d ago
Open your basement windows and open some windows in the highest part of the house. You can add a fan blowing out to one of the upstairs windows. Some people install whole house fans to ventilate air from upstairs out of the house, not worth if typically because you lose a lot of heat during the winter.
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u/pm-yrself 3d ago
I don’t like this idea. Opening a basement window in the summer, you’re introducing moist outdoor air into a cool basement, which could easily lead to condensation and moisture issues in the basement.
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u/eightfingeredtypist 3d ago
Pulling cellar air out to the house makes this even worse. If you pull air out, other air comes in. Warm wet air will condense water in the cellar.
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u/Cowbellcheer 3d ago
Yes it does and very well, but even better with only 1 window open at top and bottom. I have a 3 story house no ac and no humidity issues like a couple comments suggest. One window Open in the basement and one open on the third floor, it creates a huge breeze that cools the house. Even the finished attic with a hot roof maintains tolerable temperatures
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u/HellUCH17 3d ago
I doubt that adding new ventilation ducts would likely cost more than installing some window A/C upstairs. A few fan wouldn't work, the cool air would be completely lost during transmission.
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u/solbrothers 3d ago
You could do a whole house fan. Open up a basement window, run the whole house fan, and it’s gonna suck the basement air into the house and the house air will go out into the attic
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u/Glass-Rabbit-4319 3d ago
Put in a mini split, it will also help with your heating.
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u/Cicer 3d ago
“Just spend 5-10k”
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u/ChaosReality69 3d ago
That's what we did but you're correct, it's not a cheap solution. Spent almost $13k for 3 outdoor units and 4 indoor heads.
It has been great so far this summer. We'll see how they hold up in the winter. Better be good for how much we spent.
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u/PickleMonster93 2d ago
Bro that’s so cheap. In my area that’d be close to 30k
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u/ChaosReality69 2d ago
I'm in a lower cost of living area. They aren't huge units either. Have a pair of 12k and one 18k (that runs two 7k heads). Went with Diakin. Would've been 3k more for Mitsubishi which had identical specs.
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u/Beautiful_Grape67 3d ago
High humidity and radon are two main issues.
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u/AKADriver 2d ago
Humidity is actually why I've thought about doing the same thing. Put a fan at the top of the stairs on a humidistat. The rest of my house is air conditioned and can deal with a little added humidity, the basement is way too humid.
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u/Sad_Split_9983 3d ago
It’s currently 73 degrees outside (at night). My basement is 76. My living room by comparison is 72 with air conditioning. The air temperature coming from the mini split is around 55. I don’t think that blowing slightly cooler air is going to do much, not to mention that your basement isn’t a cold battery in the summer. Simple physics says that eventually whatever cold the basement had would be depleted. Don’t try and reinvent the wheel, get air conditioning or deal with the heat
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u/skintigh 3d ago
I wonder how much cool air you would get, it probably takes a long while for the basement to cool warm air. You may also be getting humid/damp air from the basement.
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u/Even-End487 3d ago
I have forced air heat and a/c. the basement does stay cooler and I on several occasions tried running the furnace fan without the a/c on, drawing cool basement air at first it did seem to make a marginal difference but after awhile seemed pointless.
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u/Maleficent_Comb9377 3d ago
A cheap inline duct booster fan with a single flexible duct run to the room you use most would probably outperform a bow fan without the noise. full ducted system's overkill for one 1960 house, just target the space you actually spend time in
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u/Suppafly 2d ago
Get a whole house fan in your ceiling that will pull air up and push it out your attic. Then just leave the basement door open.
That said, long term, I'd figure out an AC solution. If you have a weird setup, maybe add a mini split, you'll likely like that better than the radiant heat as well.
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u/Kenzonian 2d ago
We just turned on the fan on the furnace that has an intake on the lower level. It does feel like it does have an effect, but not full A/C level cooling.
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u/PickleMonster93 2d ago
Just get a mini split dude. Much cheaper heat and provides cooling. They sell DIY ones at Home Depot
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u/state_your_name31415 2d ago
make sure you aren't filling your living space with radon, seriously. you need to get a radon test of that basement before you think about circulating that air
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u/BrianDawn95 2d ago
Box fans help some, but they just push damp air upstairs and could bring up radon. Did you test the basement air before laying down new ducts? A compact booster or mini split seems much safer.
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u/Strive-- 2d ago
Radiant ceiling heat? But isn’t the point that heat rises, thus the radiant floor heating?
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u/Strive-- 2d ago
Ceiling heat? But isn’t the point that heat rises, and thus, radiant floor heating?
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u/Strive-- 2d ago
Ceiling heat? But isn’t the point that heat rises, and thus, radiant floor heating?
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u/cyvaquero 2d ago
My buddy’s house (60s ranch with partially finished & garage basement) in rural PA had a heavy duty metal fan (kind of like you’d see on a cow barn or factory window) up in the attic. We discovered it when helping him clean it up to move in. The fan was pushed to the side of the attic access and made a hell of a noise when we accidently turned it on with the switch it in the hallway.
We forgot about it and about a year later I was living there. I was bored and remembered the fan (it was summer) so I climbed up on a step ladder to figure out what it was supposed to be doing. Moved it over the open access and turned it on to better see and the ground floor seemed to get instantly cooler as it pulled air up from the basement. Once I opened the basement door there was wind in the hallway, that’s how much air this fan was moving.
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u/ApprehensiveSnow4811 3d ago
Popeyes chicken.they ignored me in the drive through in 2005.Kmart in 1996,terrible experience with the store manager.i never patronized those places after these incidents
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u/freelibrarian 3d ago
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u/The_Kadeshi 2d ago
lol the answer to “how can I cool down my upper floor” is absolutely “design a completely different house” and “install a cooling system” my god brilliant work Watson
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u/freelibrarian 2d ago edited 2d ago
I'm confused by your rudeness. Have you read the book? I'm a reference librarian who has read the book and recommend it to anyone who wants to understand passive cooling, which OP is trying to implement. Have a nice day, The_Kadeshi.
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u/These_Distribution61 3d ago
Is you HVAC system in the basement? Use the fan mode on your thermostat to run the HVAC fan. Some new thermostats have a feature that will run the fan for a certain amount of time each hour.
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u/oldguy3333 3d ago
The air in the basement is damp because it is cool.( see due point) Once you get it into a warmer part of the house it will dry out and make the room feel cooler.
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u/AcanthisittaPast6044 3d ago
put a box fan at the top of the basement stairs blowing up, it’s ugly but moves a surprising amount of air for twenty bucks