Pumping heat from upstairs to downstairs in winter...?

[Aardvark]

We recently moved into a new apartment. It's nice and small, and there is a wood burning stove on the upper level which houses the kitchen, lounge, and dining room. The office and bedroom are both downstairs. I've found two sources of environmentally friendly biomass (a municipal biomass waste depo and a furniture manufacturer around the corner) - so I plan on pushing the stove to its limits through this coming winter.

The question is: given that the stove is on the upper level (and heat rises), is there a way to sensibly get some of the heat downstairs? Two options that I have considered are presented below. Both seem ridiculous and not feasible.

Idea 1: Move the warm air from the top to the bottom by placing a flexible duct in the stairwell with a regular fan pushing/sucking the air down. The apartment is so small that the outlet of the flexible duct could conceivably be placed in a strategic area to maximize heat to that area.

Idea 2: Same as above, but instead of just blowing the air around, rather invest in a super small heat pump that will transfer the heat from the top level to the bottom level more efficiently... I'm wondering what the investment would be here - is it even possible to get such a small heat pump?


This seems like a fun project, and even if I don't action a solution I am enjoying thinking through it :)

PS: I don't own the apartment, so I am not up for major projects/investments.

[mistymoney]

celing fan down the stairwell?

[Aardvark]

I don't think a single fan would be good enough, and I rent, so not willing to take on large projects.

I am thinking of buying a heat pump like this one: https://boulder.craigslist.org/app/d/boulder-delonghi-pac-an140hpewc-whisper/7524403043.html

[SweatingInAR]

Do you have central heat or AC that could run its circulation fan? That would be the easiest!

Portable AC units/heat pumps might cost as much in electricity as 15x fans. I pulled some random numbers from the internet and a box fan consumes 73W while a portable AC will consume 1kW. Of course, more heat isn't the end of the world... but you could run a space heater plus a few fans to get the same effect.

It would be awfully slick, though... You could set up a single-hose portable AC to cool the room in which the stove resides. Run its exhaust down the stairs to a cold room. You may need to add a booster fan to its exhaust duct or go up a few duct sizes. I don't know how long of an exhaust hose a portable AC is made to run.

On the other hand... Something like this 8" fan with 25' of duct might be good enough for a proof of concept:
https://www.amazon.com/iPower-Booster-Inline-Exhaust-Grounded/dp/B093G83VX1

[Aardvark]

@SweatingInAR
YES! That fan+duct might be a great way to test things out. And, YES - this seems like a fun opportunity to be "awfully slick"! haha

In retrospect I think this thread fits better in the "Do it Yourself Discussions" section of the forum. Do you know whether I can move this thread there? Or should I start a new thread?

[zolotiyeruki]

@SweatingInAR
YES! That fan+duct might be a great way to test things out. And, YES - this seems like a fun opportunity to be "awfully slick"! haha

In retrospect I think this thread fits better in the "Do it Yourself Discussions" section of the forum. Do you know whether I can move this thread there? Or should I start a new thread?

You can alert a moderator and request the thread be moved.

[Aardvark]

I actually just found a "move topic" button at the bottom of the thread and did it myself.

Happy days! I hope some other people are as excited about this ridiculous project as I am! haha

[ChpBstrd]

The arrangement of the floors suggest this apartment has a main floor as the first floor level and a basement with the bedroom/office. Depending on the climate where you live, you may find that the basement stays a fairly steady temperature because it is surrounded by earth. Additionally, a lot of people sleep better in a cooler environment like this bedroom will be. You might actually like it as-is. Now, if you're surrounded by permafrost, it might be a different story.

Ideas:

1) If you don't like the idea of a cooler bedroom, maybe consider getting a used but clean "tower fan", removing the base, and mounting it sideways on the wall or ceiling of the stairwell. This could be done with some picture hanging nails and picture hanging wire so as not to unduly alter the apartment. Set it to blow upstairs air downward, so the air between the floors mixes. Something like this would not take up too much room or get in the way:

https://www.bestbuy.com/site/holmes-31-in-oscillating-tower-fan-white/5073524.p?skuId=5073524&ref=212&loc=1&extStoreId=1438&ref=212&loc=1&gclid=Cj0KCQjwguGYBhDRARIsAHgRm4_SZnDUBoNcflVwMYNUVs0qCAzUYVCqeV0lJF1hDR0BQ67JQjXSvgAaAg3tEALw_wcB&gclsrc=aw.ds

2) Depending on the specifics of your stairwell, you could create "an art" using a few pieces of 4" or 6" metal duct suspended from wires attached to a hook in the ceiling of the top floor and reaching down the stairwell so that it hangs to within a few inches of the basement floor. You could paint, wallpaper, paper mache, add sculptural elements, use fabric, add wood veneer, or do all sorts of things with this hanging duct so that it looks intentional, but the secret is a little fan at the bottom that sucks cold air off the basement floor and blows it to the the upstairs ceiling where it will mix with warm air. This will cause warm upstairs air to come downstairs to replace the air you removed through the duct. The fan could be a cheap little under-desk type fan, or it could be an actual duct fan like the one below, depending on your artistic vision.

https://www.amazon.com/VIVOSUN-Inline-Booster-Noise-Grounded/dp/B01C82SYZ0/ref=sr_1_13?keywords=4+inch+fan&qid=1662588349&sr=8-13

[Aardvark]

@ChpBstrd - The lower level is "semi basement". The floor is about 3 feet below ground level. very good point that I should first see whether this is necessary. We are based in Boulder Colorado, far from permafrost. I do expect that we will need a bit of heat downstairs, and it would be fun to meet the downstairs heating need using the upstairs stove. Thanks for the ideas.
I don't expect your first idea to be very effective, but maybe that's all we need given that we're half under ground.
The second idea is similar to one posted earlier in this thread and I really like it.

Thanks again!

[NorCal]

Is the regular HVAC ducted, and is there a return from upstairs?

They make small HVAC booster fans that sit in registers to pull additional air through. This could pull air through you HVAC ducts if your registers and returns happen to be in the right spots.

I realize it’s low likelihood, but it would be a neat solution if your apartment is laid out that way.

[sonofsven]

We recently moved into a new apartment. It's nice and small, and there is a wood burning stove on the upper level which houses the kitchen, lounge, and dining room. The office and bedroom are both downstairs. I've found two sources of environmentally friendly biomass (a municipal biomass waste depo and a furniture manufacturer around the corner) - so I plan on pushing the stove to its limits through this coming winter.

The question is: given that the stove is on the upper level (and heat rises), is there a way to sensibly get some of the heat downstairs? Two options that I have considered are presented below. Both seem ridiculous and not feasible.

Idea 1: Move the warm air from the top to the bottom by placing a flexible duct in the stairwell with a regular fan pushing/sucking the air down. The apartment is so small that the outlet of the flexible duct could conceivably be placed in a strategic area to maximize heat to that area.

Idea 2: Same as above, but instead of just blowing the air around, rather invest in a super small heat pump that will transfer the heat from the top level to the bottom level more efficiently... I'm wondering what the investment would be here - is it even possible to get such a small heat pump?


This seems like a fun project, and even if I don't action a solution I am enjoying thinking through it :)

PS: I don't own the apartment, so I am not up for major projects/investments.

Have you run a wood stove for a season before? I'm a little concerned with your choice in fuel. You need dry wood and a biomass dump sounds like it's not clean and properly dried firewood.
A furniture manufacturer sounds a little more promising, but definitely no varnish or other types of finish, and no plywood.
You'll need a place to store the wood out of the weather as well, and the ability to cut and split it.
Most likely though you'll need very little heat since you'll be warmed up by carrying firewood up to the top floor all day ;-)

[BudgetSlasher]

As has already been mentioned if the apartment has ducted heating cooling and the fan can be controlled separately I would run the fan to move air/mix. Some thermostats even allow you to set the fan to run some many minutes every hour. -Upgrading to a smart thermostat might be something you can do, at least while you live there-

If there is so central fan already in place, I would do something akin to Option 1.A couple changes I would make personally:

First I'd replace the flex duct with rigid metal and with duct sealing mastic at the joints. There is much less resistance and turbulence in metal ducts and the mastic stops air leakage.

Second, I am uncertain what a regular fan is, but I would use an line duct fan and preferably one that has or can be used with a fan speed controller. These can be used in all kinds of applications, but the internet seems to think/market them primarily for grow operations.

It sounds like any project you undertake would be quick to deploy and use readily available materials. Given that and the fact you have not been through a winter in the apartment, I suggest having a plan for if you need/want to move heat around, but that you wait and experience how the apartment actually behaves in the winter and how you live in it before to do anything.

[Aardvark]

The past few days in Boulder were surprisingly cold - it got down to the low 40's. This was a great test for me to feel out the temperature in the lower level, and also to test the wood stove.

@sonofsven your points are totally valid, and I will have to assess the city's biomass before using it. However the offcuts from the furniture shop are untreated, kiln dried, already quite small, and they're available in a steady supply. And the shop is about a mile from my house, so I can pick them up with minimal effort. I really think this is a promising solution.

@BudgetSlasher thanks for the additional comments. Using a rigid metal duct seems like way more effort than dropping something like this down the stairwell. https://www.amazon.com/iPower-Booster-Inline-Exhaust-Grounded/dp/B093G83VX1
Not only more effort, but a rigid duct would probably require some basic construction like nails, and brackets to support the duct. For this reason I think I am going to go with the flexible ducting.
I'd appreciate it if you had a look at that link and let me know what you think of that ducting and that fan - and that price.
I think I see the value of an airspeed controller, so I will either add one to that package, or buy:
https://www.amazon.com/iPower-GLFANXBOOSTER8CTRLV1-Variable-Controller-Adjuster/dp/B08N6JTBF1/ref=psdc_5446824011_t3_B093G83VX1
plus
https://www.amazon.com/dp/B0791TKB51/ref=emc_b_5_t
But that setup is a bit more expensive. I am trying to figure out where to spend money, and where not :)

If my plan doesn't work out I will be using the electrical heating in the apartment. Certainly not the end of the world, but not half as fun as a DIT project to save tons of money and carbon emissions :)

Thanks for all the support to this thread! :)

[BudgetSlasher]

The past few days in Boulder were surprisingly cold - it got down to the low 40's. This was a great test for me to feel out the temperature in the lower level, and also to test the wood stove.

@BudgetSlasher thanks for the additional comments. Using a rigid metal duct seems like way more effort than dropping something like this down the stairwell. https://www.amazon.com/iPower-Booster-Inline-Exhaust-Grounded/dp/B093G83VX1
Not only more effort, but a rigid duct would probably require some basic construction like nails, and brackets to support the duct. For this reason I think I am going to go with the flexible ducting.
I'd appreciate it if you had a look at that link and let me know what you think of that ducting and that fan - and that price.
I think I see the value of an airspeed controller, so I will either add one to that package, or buy:
https://www.amazon.com/iPower-GLFANXBOOSTER8CTRLV1-Variable-Controller-Adjuster/dp/B08N6JTBF1/ref=psdc_5446824011_t3_B093G83VX1
plus
https://www.amazon.com/dp/B0791TKB51/ref=emc_b_5_t
But that setup is a bit more expensive. I am trying to figure out where to spend money, and where not :)

There is no reason that flexible duct would not work. It will have higher resistance than a similar length rigid duct and as a result less overall airflow.

You can always add a fan controller if you find you need or want to run it at a slower speed.

Your project is both an edge case and outside of my of experience, here is my thought process. As a rule of thumb 1 CFM of air flow is enough for 1-to-1.25 sq/ft of room space (https://inspectapedia.com/aircond/Air_Flow_Rates.php) so in a heating system you might be looking at enough airflow for 420 sq/ft with that booster fan. But air coming out of heating system is usually 40-70 degrees warmer than the air entering the heating system or put another way the air coming out of the duct is 100-110*F (https://inspectapedia.com/heat/Warm_Air_Supply.php).

I doubt you will be moving air that hot or with that big a temperature difference -probably more like 75*F to 55*F or half the low end of the temp delta- which will require more air flow, I do not know the math for calculating this. I also didn't notice the size of the space you are moving air into or how warm you want it to be; size and how well insulated or not a semi-basement is will have a big impact on how much heat you need to move.

Also I would not expect a booster fan -meant to assist air that is already moving- to meet its rated CFM alone. Really I expect that most fans CFM rating are going to be overstated -at least as they would be used in the real world/as intended- and especially so at the price point of the one you posted.

In short, if I were building what you are considering I would be concerned that 10s of dollars fan moving room temperature air into a semi-basement will move sufficient air to meet the goal.

[sonofsven]

The past few days in Boulder were surprisingly cold - it got down to the low 40's. This was a great test for me to feel out the temperature in the lower level, and also to test the wood stove.

@sonofsven your points are totally valid, and I will have to assess the city's biomass before using it. However the offcuts from the furniture shop are untreated, kiln dried, already quite small, and they're available in a steady supply. And the shop is about a mile from my house, so I can pick them up with minimal effort. I really think this is a promising solution.

@BudgetSlasher thanks for the additional comments. Using a rigid metal duct seems like way more effort than dropping something like this down the stairwell. https://www.amazon.com/iPower-Booster-Inline-Exhaust-Grounded/dp/B093G83VX1
Not only more effort, but a rigid duct would probably require some basic construction like nails, and brackets to support the duct. For this reason I think I am going to go with the flexible ducting.
I'd appreciate it if you had a look at that link and let me know what you think of that ducting and that fan - and that price.
I think I see the value of an airspeed controller, so I will either add one to that package, or buy:
https://www.amazon.com/iPower-GLFANXBOOSTER8CTRLV1-Variable-Controller-Adjuster/dp/B08N6JTBF1/ref=psdc_5446824011_t3_B093G83VX1
plus
https://www.amazon.com/dp/B0791TKB51/ref=emc_b_5_t
But that setup is a bit more expensive. I am trying to figure out where to spend money, and where not :)

If my plan doesn't work out I will be using the electrical heating in the apartment. Certainly not the end of the world, but not half as fun as a DIT project to save tons of money and carbon emissions :)

Thanks for all the support to this thread! :)

The furniture scraps sound promising, but only as part of a fire. You're not going to get a long slow burn from smallish hardwood scraps.  I burn scraps in my shop when I'm in there and you need to feed them constantly to sustain any heat.

[Aardvark]

Thanks @BudgetSlasher  - maybe I've gotten so excited about frugality and dipped into stinginess. I will research this more and consider a bigger/better system. I really appreciate the thoughts and ideas.

@sonofsven The offcuts from the furniture shop have been working very nicely. There is a nice distribution from kindling to cutting boards-sized pieces. The stove is one of those ultra efficient modern ones, and I am hopeful that if I load it up and choke it a bit it will burn through the night. I alos really don't mind the process of reloading it with more wood - feels satisfyingly primal. haha.

At the end of the day we have an electric heating system, and the thermostat will end up compensating for the difference between what heat I achieve with the fire and the temperature that we desire. I will go back to the drawing board and let y'all know once I have an updated plan.

Happy Days!

[sonofsven]

Thanks @BudgetSlasher  - maybe I've gotten so excited about frugality and dipped into stinginess. I will research this more and consider a bigger/better system. I really appreciate the thoughts and ideas.

@sonofsven The offcuts from the furniture shop have been working very nicely. There is a nice distribution from kindling to cutting boards-sized pieces. The stove is one of those ultra efficient modern ones, and I am hopeful that if I load it up and choke it a bit it will burn through the night. I alos really don't mind the process of reloading it with more wood - feels satisfyingly primal. haha.

At the end of the day we have an electric heating system, and the thermostat will end up compensating for the difference between what heat I achieve with the fire and the temperature that we desire. I will go back to the drawing board and let y'all know once I have an updated plan.

Happy Days!

Good luck and enjoy your woodstove heat, there's no better heat in my opinion.

[Malossi792]

In your case, as the alternative is electric (suppose that doesn't automatically mean heat pump) I would be tempted to go with the mobile heat pump you mentioned. Preferably pre-owned for the sake of frugality. Yes, it consumes more than a fan, but the 'alternative', already installed electric heating also does, and it would do (I think) an order of magnitude better job of moving heat to where it's desired.
I love a good thought experiment in efficiency!

[Aardvark]

@Malossi792
It would be fun to explore this idea with you.
Do you have this type of thing in mind:
https://www.facebook.com/marketplace/item/604220701075287?ref=search&referral_code=null&referral_story_type=post&tracking=browse_serp%3A8a058181-a666-4013-82e2-3ffdc19da23b

A swamp-cooler obviously wouldn't work, but a regular AC probably would be WAY better at pumping the heat downstairs than just an air duct moving the air itself. I would then place the AC unit upstairs and the exhaust duct downstairs. I'm assuming that the air intake is part of the unit that blows out the cold air. In a perfect would I would want to place the intake right next to the wood-burning stove.

Another thing to consider is whether I'd be able to get a unit with a long enough exhaust duct. OR whether a duct extension would compromise the unit's efficiency.

[chops]

I have found that it is better to move cooler air towards a wood stove (meaning put a fan aimed at the wood stove from the top of the staircase, to aim cold air at it) and then it seems to force warm air to spread out from the wood stove and even out the heat around my house bit better.  You may want to try that as an alternative direction to see if it helps.

Good luck!
 - Chops

[Malossi792]

@Malossi792
It would be fun to explore this idea with you.
Do you have this type of thing in mind:
https://www.facebook.com/marketplace/item/604220701075287?ref=search&referral_code=null&referral_story_type=post&tracking=browse_serp%3A8a058181-a666-4013-82e2-3ffdc19da23b

A swamp-cooler obviously wouldn't work, but a regular AC probably would be WAY better at pumping the heat downstairs than just an air duct moving the air itself. I would then place the AC unit upstairs and the exhaust duct downstairs. I'm assuming that the air intake is part of the unit that blows out the cold air. In a perfect would I would want to place the intake right next to the wood-burning stove.

Another thing to consider is whether I'd be able to get a unit with a long enough exhaust duct. OR whether a duct extension would compromise the unit's efficiency.

Yup, exactly!
I wouldn't put it close to the stove though, radiant heat can melt plastic quite quickly. I would just place somewhere that enabled me to make do with the stock duct, while blowing the cold air in the direction of the stove.
Couple more drawbacks come to mind, one is the noise because these units can be quite loud, one is the cold air blowing in your living room, and the third is finding a way to route the condensate water into the sewer.

[jpdx]

Heat doesn't rise, but hot air does. :)

[Malossi792]

Heat doesn't rise, but hot air does. :)

That's their problem, stove is upstairs.

[Aardvark]

@jpdx - the heat causes the air to expands, resulting in decreased density, causing it to rise... But contained in that hot air is the heat that caused it to expand, decrease it's density, and rise. So the rising air takes the heat with it - so I do think it's correct to say that the heat rises. But I take your point that the heat is just getting a ride on the air which is rising.

... or do you disagree with me?