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Exchanging air from top floor ceiling to basement floor?

 
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I can't seem to find the right place to post this question.  For years I've wondered how I could make use of the cold basement in summer to cool our house.  But on the flip side we'd like to be able to send hot air from our ceiling down to the basement in the winter to help heat it.  

I've thought about framing some duct to pass through our main floor into the basement, and extend the duct up to the vaulted ceilings.  Then adding a fan to push the air whichever direction.  

I recently learned there are things called "Pass-through registers" that do just this, except it appears that is only meant to live in the floor space with no needed ducting.  So the air would be exchanged only between floor of the main floor, and the ceiling of the basement.

Does anyone have experience with either setups?  I'm not sure how much air I could get moving through the much longer duct needed to extend up to the ceiling and also down to the basement floor, although the temperatures in those locations would allow for the optimal heat exchange.

I'm wondering if this is worth it.  If I just did the simpler "pass-through" I could also a ceiling fan in our basement to stir the air.  On the other end,  I'm sure the ceiling under the roof is at least 20 degrees hotter in the summer than the floor where the pass-through would pull the air from, but I do have a ceiling fan in the main area with vaulted ceilings.  So I could leave that cranking to mix the air as much as I can.

I can't do an attic fan because we have no attic.  I'm in Colorado where nights are significantly cooler.  I looked into using one to pull air out of our home in the summer, which would be most effective around sunset.  But there would be no benefit for this in the winter.  Regardless we were told the attic fans don't work well unless you have a ceiling.

Thanks!
 
pollinator
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One thing I would watch for is the humidity at different levels of your house. Redirecting air also means pumping water vapour. Moving warm air into a cool basement can sometimes mean adding water vapour which will condense on cool surfaces and encourage mold. I'm not saying don't do it, but watch for problems
 
master steward
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Someone I knew when we lived in Indiana put a box fan on the stairwell to her basement to move the air onto her first floor.  

Would something like this work for you?
 
S. Marshall
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I'm thinking humidity wouldn't be an issue because it's so dry here in Colorado anyhow.

I'm not sure the boxfan would work because although my basement stairwell is wide and there is no door it has a turn that would obstruct the air flow.  

Good thoughts though!
 
pollinator
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I have considered adding something like this with flexible duct work to move air from the upstairs to the main level.  I probably should have done this from the start when I was first building but I didn't think of it at that time.   But, I can't find anything like this that is reversible.
https://www.amazon.com/AC-Infinity-CLOUDLINE-T6-Temperature/dp/B074XBXFPD/ref=sr_1_11?keywords=duct+booster+fan&qid=1641413750&sr=8-11

I did find this version that is reversible and could be set up to do what you are considering.  With this the fans can be set in different directions so you could pull cool are in one direction and push warm air in the other direction and possibly get better circulation.  Maybe push the cool air from the basement to one room and pull the warm air from an another room to the basement to get more circulation through the house.
https://www.amazon.com/Tjernlund-X2R-Xchanger-Reversible-Basement/dp/B01BB2S0L6/ref=sr_1_2?crid=1BGUSWYX8G26H&keywords=duct%2Bfan%2Breversible&qid=1641414203&sprefix=duct%2Bfan%2Breversible%2Caps%2C139&sr=8-2&th=1
 
S. Marshall
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Interesting.  Thanks for those links.  The double fan idea is a new thought.  

Too bad a simple straight duct like this isn't a common thing.  I mean, unless something here can explain why this idea doesn't work it seems like such an easy idea---especially in a dry climate like Colorado.  

If you planned on using the flexible duct because of twists and turns, doing so will definitely slow down the air.  I remember that about hooking up oven vents.

When it comes to finding the best fan, I'll bet people over in the climate battery related subreddits have suggestions.  They push tons of air through tubes underground.

(edit: correct spelling)
 
pollinator
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What does this mean?
I'll be people over in the climate battery related subreddits have suggestions
Would 200mm air condition pipe work, with a fan at the top?
 
S. Marshall
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John C Daley wrote:What does this mean?
I'll be people over in the climate battery related subreddits have suggestions
Would 200mm air condition pipe work, with a fan at the top?


I meant to write "bet" not "be".   I'm still not sure what pipe I would use, but I'm guessing it would be normal duct pipe.  I'm sure you can use whatever though.  The fan choice would be an important factor as to what fits.
 
pollinator
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Mine is going out of the basement, up thru the collector and back in the clerestory window in the upstairs.  Here is the write up.

collector

I am using 6 computer fans 12V rated at 108 cfm each.  I am getting nearly 700 cfm out of them.  Got lucky and got some amazing fans for this cheap as well.   Here is the pricey version of what I am using.  Driving them with a recycled computer power supply wired to always turn on.

fans
 
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The box fan in the stairwell would work fine in spite of bends in the stair, as long as it was pulling air through the well. It would only be in case of pushing air at a bent path that you would get bad eddies and possibly poor performance.
 
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Hi,  What type of HVAC system do you currently have? If forced air, slight modifications to it will improve heating and cooling, Thereby not having to open up walls to insert pipes around obstacles like wiring or plumbing.  How many rooms will you be heating or cooling?  A great room with an inside wall could do it. I would place the fan halfway in the pipe.  

I don't understand why you need to heat or cool the whole space to the ceiling. I might have the space I occupy heated or cooled.  I would place the end of the duct at head level to heat or cool the body and not the whole space. Alternatively a damper to shut off air flow would be of use if you make a full run from ceiling to floor. You could divert air into the living area with a register and damper, or exchange it completely.  

When setting up your system look at the circulatory system of a dolphin. I tried to model my system after it. Works wonders.  I use 25% less fuel than my neighbors.

May God grant you wisdom for your project.
 
S. Marshall
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Arthur Angaran wrote:....



Thanks Arthur Angaran.  I do currently have an HVAC system.  I'm no expert but I don't believe it was created very well.  It doesn't seem very efficient or effective.  But I will look into the dolphin model, very interesting.  

The reason for taking air from the ceiling is only to maximize heat exchange.  I can understand your suggestion to keep it head level.  I guess my idea is to try and cool the whole area (in the summer) and to suck the warmest air that sitting at the ceiling in the winter for the basement.  The main room with cathedral ceilings is the center of activity.  I'm not dismissing your idea at all, I'm trying to understand if it makes more sense.

I'll be considering all this.  Let me know if you think of anything else, please!
 
pollinator
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I think you would need to install a duct and fan that pulls air from a high point in the ceiling and delivers it to the basement. But then you have to consider where the air will come from that "fills the void" created by that suction. You'd maybe need a floor register with ducting that reaches down almost to the basement floor, so that all the warm air forced down into the basement is replaced by the coldest air near the basement floor. Assuming you have a door at the top of your basement stairs, that would need to remain closed for this loop to work.

Fighting against the natural heat stratification in a room with cathedral ceilings to pump warm air into the basement is a tall order, as fighting nature usually is.  I'll share the system I just got running and maybe inspire you. Not the same scenario you're looking for, but perhaps the same principles could warm all the air in your house, and even the cool air flowing down the basement steps would still be warmer than it was since all the air is warmer. It requires some sort of south facing glazed enclosure where basement air can enter low and hot air can exit high.

Porch-heater.jpg
Diagram of air flow
Diagram of air flow
Solar-Porch.jpg
South facing enclosure
South facing enclosure
Basement-window.jpg
Basement window cover, insulated on the inside. Delivers basement air to porch.
Basement window cover, insulated on the inside. Delivers basement air to porch.
 
S. Marshall
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Matt Todd wrote:



Hi Matt.  The system you created is quite clever.  

We actually do not have a door to the basement.  Instead it is a quite large stairwell.  Because of this I'm not sure how important it would be to fill the void (though I could be wrong).  If I simply used this duct and fan to push warm air down there do you feel it would displace the cold air at least we well as the system you created?  I realize your system is pulling air up through the basement window, but my south side doesn't have any basement access (not even a window with a well up to the ground).

When you said "fighting against the heat stratification... is a tall order", was that specifically because the room has cathedral ceilings?  Is this specifically because the duct is too long for the fan's ability or another reason?  Do you feel it would be much simpler/easier to move the air by not going all the way up to the ceiling?  Because I could use the ceiling fan to mix the air so going all the way to the ceiling isn't as important.  
 
Michael Fundaro
pollinator
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If you draw the warm air from the ceiling and push it to the basement it will slowly and gradually move air from the basement up the stairs to the main level of the home.  In the summer if you draw the cool air from the basement to the main level it will slowly and gradually move air down the stairs to the basement.  You probably wont feel a breeze or draft because the volume of air pushed through an 8" duct is minimal compared the volume of air moving through the stairwell.
 
S. Marshall
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Michael Fundaro wrote:If you draw the warm air from the ceiling and push it to the basement it will slowly and gradually move air from the basement up the stairs to the main level of the home.  In the summer if you draw the cool air from the basement to the main level it will slowly and gradually move air down the stairs to the basement.  You probably wont feel a breeze or draft because the volume of air pushed through an 8" duct is minimal compared the volume of air moving through the stairwell.


Forgive me for sounding dumb here, but I thought that was the point.  To slowly and gradually exchange air, not to have a breeze, but to exchange air through convection.  Does this not work?
 
Matt Todd
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Seth Marshall wrote:
We actually do not have a door to the basement.  Instead it is a quite large stairwell.  



I think this is a problem because no matter how much warm air you "pump" down, it would rise right back up the open stairwell with no resistance. There's nothing to keep it downstairs. Not sure of your house layout, but maybe if you pumped the hot air into a specific basement room or at least the farthest point from the stairwell then you might see some heating from this air.

Seth Marshall wrote:
When you said "fighting against the heat stratification... is a tall order", was that specifically because the room has cathedral ceilings?  Is this specifically because the duct is too long for the fan's ability or another reason?  Do you feel it would be much simpler/easier to move the air by not going all the way up to the ceiling?  Because I could use the ceiling fan to mix the air so going all the way to the ceiling isn't as important.  



I was speaking generally here. Just expressing that going from warm air at the top of a tall ceiling to the lowest point in your house is quite the battle against nature. I don't have enough technical knowledge of ducts and fans to speak to the specifics of how well you could pull air down to the basement.
 
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