I want to transfer wood stove heat to lower level of the house.

[laynes69]

If it was me, I would just use heat tape if its not alot of pipes. If you open that area into the living space, it will cool that area alot when its that cold. I wouldn't want to heat that cold air from under there on top of the rest of the house. Maybe use a timer with heat tape, or something else on that effect. If its electric you are worried about, see what each one will draw. Just like said prior, heat will only rise. Thats why we heat with a woodfurnace, the whole house stays the same temp. Its forced air heat.

 

[loknlod]

It was, on the first page of this thread. If you want warm air down there for warm floors, you'll have to force it to go there. Physics 101. Otherwise, because it's an unused crawlspace, insulate the floor from below, let the rest sit as 'dead air' space.

Ok Mike, we've moved on from the original post. The natural convection idea was brought up shortly after I opened this thread and I had mentioned I was going to try it. Natural convection is not meant to force warm air where it doesn't want to go.

I still plan to use the ducting that is in place with a little "in line" blower fan, I just don't know if I should force the hot air down or force the cold air up.

Does it make a difference? Is there a good reason to try 1 or the other?

 

[Mike Van]

I'd think you'll want to force the warm down, as drawing the cold from the un-insulated c.s. will only suck in more cold? And whats up with the cold floors? I thought all Alaskans had fur-lined moosehide mukluks?

 

[trimmmed]

Gee, it didn't work? What a surprise! Warm air won't go down on it's own after all.

LOL! Not "naturally" anyway

 

[KsWoodsMan]

It was, on the first page of this thread. If you want warm air down there for warm floors, you'll have to force it to go there. Physics 101. Otherwise, because it's an unused crawlspace, insulate the floor from below, let the rest sit as 'dead air' space.

I remember making the orginal suggestion of putting in a cold air return to draw the cold air out of his lower level. I was quite surprised that so many people didnt understand natural convection and thought I was suggesting that convection would push warm air down there. That was not the case.

The suggestion was to draw the cold air out. drawing it out means it would be replaced by warmer air, return it to the heat source and re-heat it. Any one that doesn't follow what I posted please re-read my earlier attempts to explain it. That would be more productive than rehashing warm air convection, again.

Loknlod, the return line needs to be heated to create draw. The more heat, the more draw. The higher it goes behind the stove the more heat it will get and the faster it will travel. 90 degree bends slow things down considerably. Is the return 'duct', behind the stove, black pipe or galvanized ? Black will work better, it absorbs more heat from the exhaust flue. The closer you get it to the exhaust flue the better it should work. Something I hadnt thought of was that you might be using double or triplewall exhaust pipe. Mine is singlewall and gives off a lot of heat on a heavy burn.

I have thought about putting a larger pipe around my (single wall) flue pipe so it heats the inside of the return instead of the outside. Should be easily done with a 'TEE' one size larger than the flue pipe and a couple pieces the same diameter as the tee. And something to couple the 4" to whatever size you use around the flue pipe. My flue pipe exits the stove from the top so I will have to include an elbow in there and run the return in from the side instead of the bottom of the tee.

Yes this will cool the stack some but nothing like a fan forced heat recaimer. Keep an eye on your stack temperature to be sure you arent in the creosote danger zone. One thing about it. I won't have a 450 degree flue above my stove radiating heat across the room. It WILL be pulling cold air off my floor and out of my bedrooms using natural convection instead of electricity.

If I was going to use electricty to move the air I would push the cold air back to the heat source.

 

[loknlod]

I'd think you'll want to force the warm down, as drawing the cold from the un-insulated c.s. will only suck in more cold? And whats up with the cold floors? I thought all Alaskans had fur-lined moosehide mukluks?

Funny, I'm wearing moosehide slippers right now.

The lower level of the house has living room, bedroom, bath, washer and dryer, and crawlspace. The crawlspace door is about 4 foot by 4 foot square. If the crawlspace door was open, (entire downstairs level sharing same air) would a person be able to draw the cold up to the hot or would some air still want to come in from outside?

I'm not saying forcing hot down to cold isn't the way to go, just want to make sure you see the layout.

I guess the fan will be easily reversible so maybe this should be figured by trial and error. opcorn:

 

[BIG JAKE]

Ok Mike, we've moved on from the original post. The natural convection idea was brought up shortly after I opened this thread and I had mentioned I was going to try it. Natural convection is not meant to force warm air where it doesn't want to go.

I still plan to use the ducting that is in place with a little "in line" blower fan, I just don't know if I should force the hot air down or force the cold air up.

Does it make a difference? Is there a good reason to try 1 or the other?

Best case lok the woodstove would be on the bottom floor. Then you don't need any air handling and the convection will work on it's own. But of course where you bring your wood in, distance to top floor, total square footage, and those types of considerations may be why you put it the stove where you did-your call.
Here's my take on convection. If I missed a fair explanation previously my apology. Warm air rises and goes away from the heat source. The air that rises must be replaced where it came from at the source. Think of it like filling a bucket of water, only upside down. The ceiling is being continously filled with warm air thus forcing the colder air down towards the floor and back to the stove. This happens continuously as long as the heat source is in operation. It's called a convective loop. It works best when the stove runs all the time-not always possible since most of us have to work.
If your set on the duct method of fixing what you have, an in duct fan as stated previously would work. Try it both ways as far as cold or hot and verify best results with a thermometer over a a day or two. If you want or need to keep cost down you could trigger the duct fan with a thermostat at a lower temp say 50 degrees or whatever. You can at least make the lower living space liveable during your extreme cold. For the crawl space you could use a small computer fan either AC or DC sized for the volume you have in there. My impression was fairly small I may be way off but pressed for time. For that fan you could use a snap switch or thermostat to keep it at 37 degrees in there or what's necessary. Then it's all automatic. As things fail, use an indoor outdoor thermometer with a probe and put the probe in the crawl space with thermometer where you can view and verify temps ok in the crawl space. If you don't want to mess with that then heat tape/insulation.
On the Radon you can test for that. Ventilation is the only thing to help you there and bad for problem of heating that you have. Gotta run hope this helps. Ideas anyway.

 

[loknlod]

I remember making the orginal suggestion of putting in a cold air return to draw the cold air out of his lower level. I was quite surprised that so many people didnt understand natural convection and thought I was suggesting that convection would push warm air down there. That was not the case.

The suggestion was to draw the cold air out. drawing it out means it would be replaced by warmer air, return it to the heat source and re-heat it. Any one that doesn't follow what I posted please re-read my earlier attempts to explain it. That would be more productive than rehashing warm air convection, again.

Loknlod, the return line needs to be heated to create draw. The more heat, the more draw. The higher it goes behind the stove the more heat it will get and the faster it will travel. 90 degree bends slow things down considerably. Is the return 'duct', behind the stove, black pipe or galvanized ? Black will work better, it absorbs more heat from the exhaust flue. The closer you get it to the exhaust flue the better it should work. Something I hadnt thought of was that you might be using double or triplewall exhaust pipe. Mine is singlewall and gives off a lot of heat on a heavy burn.

I have thought about putting a larger pipe around my (single wall) flue pipe so it heats the inside of the return instead of the outside. Should be easily done with a 'TEE' one size larger than the flue pipe and a couple pieces the same diameter as the tee. And something to couple the 4" to whatever size you use around the flue pipe. My flue pipe exits the stove from the top so I will have to include an elbow in there and run the return in from the side instead of the bottom of the tee.

Yes this will cool the stack some but nothing like a fan forced heat recaimer. Keep an eye on your stack temperature to be sure you arent in the creosote danger zone. One thing about it. I won't have a 450 degree flue above my stove radiating heat across the room. It WILL be pulling cold air off my floor and out of my bedrooms using natural convection instead of electricity.

If I was going to use electricty to move the air I would push the cold air back to the heat source.

I ran the pipe right behind the stove pipe (single wall) and I am sure it needs more heat to work better. I used some thin galvanized pipe (the split stuff that you can buy at Lowes) but it just doesn't heat up a lot.

 

[KsWoodsMan]

The lower level of the house has living room, bedroom, bath, washer and dryer, and crawlspace.

The crawlspace door is about 4 foot by 4 foot square. If the crawlspace door was open, (entire downstairs level sharing same air) would a person be able to draw the cold up to the hot or would some air still want to come in from outside?

I'm not saying forcing hot down to cold isn't the way to go, just want to make sure you see the layout.

I guess the fan will be easily reversible so maybe this should be figured by trial and error. opcorn:

I didn't realise there was more than one large room downstairs. Guess I never asked or it never came up. One 4" return line for 3-4 rooms is undersized.

 

[KsWoodsMan]

It is undersized if you want the down stairs to be as warm as the upstairs. If you are OK with the downstairs being cooler by more than 10 degrees it is still worth an effort so you arent spending as much for your alternative heat for the lower level. The more air you can move through that duct the closer the 2 will be to each other in temperature.

Are you reclaiming the heat from the dryer ? You are paying to heat air that dries the clothes, might as well be using some of that wasted heat to warm your home.

 

[loknlod]

It is undersized if you want the down stairs to be as warm as the upstairs. If you are OK with the downstairs being cooler by more than 10 degrees it is still worth an effort so you arent spending as much for your alternative heat for the lower level. The more air you can move through that duct the closer the 2 will be to each other in temperature.

Are you reclaiming the heat from the dryer ? You are paying to heat air that dries the clothes, might as well be using some of that wasted heat to warm your home.

Nope, I didn't intend to keep the crawlspace the same temp. as the upstairs. I figured the setup would offset the amount of fuel needed to heat the lower level by circulating the air naturally.

Reclaiming the dryer heat would not pay in our case. Just she and I and most of the clothes get air dried. Usually the dryer only gets used for a couple of loads on Sunday.

The thermostat downstairs is at about 68 so the room temp. will be just that, no matter what source of heat/air flow I use. I would prefer the wood do the heating since it is "my fuel", as compared to the fuel I buy monthly from off the fuel truck.

We run ceiling fans a lot in the house. I can't see how this little in line blower will be much worse for electricity use than them. I can always check that with a meter if I want to.

 

[Mkarlson]

If nothing else reading this thread has me wanting to try out the pipe behind the stove. I think it would be a great experiment for my children (ages 5,8,10,13) to be apart of. After reading I have no doubt placing pipe behind stove from floor to ceiling would cause the air in the pipe to travel up. What I would like to see and to show the children is the ashes/dust being sucked up from the bottom. Just for the record this would be a simple temporary setup. I have no need for this other then to satisfy my own curiosity and maybe keep the minds of my children working on things other than preparing to pass the next state required test, the schools need them to do well on, in order to get their funding for next year.

schools and their agendas

 

[RatchetJaw]

air suction

Ok there is one thing i want you to keep in mind when using the blower for the crawl space this will create a vacuum affect in the house and bring more cool air into the house then there was orrigionally. so either way the cold is gonna come in cause if the cold air cant come into the house then the warm cant transfer out it will just creat a negative pressure difference and the blower will be doing nothing for you till the pressures are eqaulized. one question I have could you use water piping instead? I plan on doing it this way one of these days ive done it before and it worked excellent take your stove out cut 4 holes in both sides directly opposite from each other then run steel pipes inside the firebox just so the are above the firebrick or i guess in some stove models below weld these in place and make sure the welds are good as in no air or Co2 can leak out .then connect the 2 most outer pipes to the 2 inner ones on the stove with some fittings so they make a solid mess of pipes to flow water through ok so here is how this works you need a small resivor say in the 5 to 10 gallon range t o hold a supply of water keep in mind this needs to be open so the sytem can breath and expand so use like a bucket or somthing like this with out a lid just make sure it can spill out now what you wanna do is run black abs pipes kinda zig zag across the floor well under it anyways between the joists then connect them all so they are in one long continous length connect 1 end of the hose to the water resivor its the return side of the system then connect the other end to the stove where the hot water will flow into the pipes then connect another section of hose between the stove and bucket . fill the system with enough water to fill the pipes and just a wee bit extra for evaporation and leave some room for the water to expand so it doesnt wind up on the floor now its real important that the water resivor is located higher up then the stove by maybe a foot or more other wise it will all siphon itself down to the level of the stove now the way this works is similar to how your coffee perk works the cold water in the metal tubes in the fireplace will heat up and get pushed out cause the cold water is trying to rush in behind it and its denser so it will just start a natural convection cold in hot out cold in hot out and it will just keep returning to the resivor but in the process it will loose its heat to the floor underneath works just like a car radiator. Also the beauty of this id that you can also use this type of system to heat up your hot household water instead of using a propane burner or god forbid electric and if you do it this way just eliminate the water resivor and use your water heater tank as the resivor to do this use a Y adapter on the vold water supply side and one on the other aswell this will now make this a pressurized system but since not water will be escaping the hot water tanks are already built to handle the pressures of hot and expanding water also no need to worry bout the house pump if you have one running the system will stay pressurized but the water heat transfer convection system will still keep it moving then you can kill the power or gas to the hot water heater and if ever in a pinch the hotwater heater could itself be turned back on to heat up the floor like say you run out of that free fuel also as a note if you use the hotwater heater method make sure you also put a brass inline valve on both sides of the hot water tank so you can efectivly close of or also use them to adjust your temperature settings in the floor it can only flow as fast as you let it. then there is no need to worry about the house pressure changing and bringing in more cold air .:greenchainsaw:http://www.**********/econtent/images/uploads/dhw1.gif as per this diagram I found just insert your in crawlspace pipeing between the tank cold side and the stove.Also check this site out could save you the headache if your not much of a do it your selfer. http://www.hilkoil.com/

 

[KsWoodsMan]

Loknlod, I wasnt thinking of keeping the crawlspace the same temp as upstairs. I was thinking of getting the lower living area warmer by pulling the cold air from there through the crawlspace back to the stove to be heated. As long as the crawl space was kept above freezing the pipes in there dont freeze. If the air in there is 60* instead of 25* the floors will feel warmer.

If the 4 foot by 4 foot crawl space door was open to the lower level I dont see how there could be much negative pressure through a 4 inch round opening getting it back up to the wood stove. Circulating air inside the house shouldn't be pulling in cold air from outside.

Initially, I suggested an opening at floor level downstairs into the crawl space. Then install a completely vertical pipe, behind the wood stove, going through the floor to the crawlspace directly below the stove. The air in the vertical pipe would be warmed. The air in it would rise pulling cold air out of the crawlspace. The floor level opening downstairs would allow cold air from that room to flow into the crawlspace. Air would circulate through the house naturally instead of the cold air stacking up downstairs.

To check for any airflow through the return, strike a match at the opening downstairs. With the woodstove burning, if it draws the smoke/flame into it, it is working. The question then becomes how much better can you make it work that will satisfy the need for heat down there without firing up the gas/oil burner. That was why I asked about if the top pieces were shiny galvanized or black flue pipe. Then I offered the suggestion of putting a piece of larger pipe around the flue to directly warm the air traveling through it instead of only indirectly warming it. Directly warming it will pull much more air from down there.

I wasn't considering the cost of electricity. I was thinking more about the avaiability of it during an outage. Without electricity the downstairs would be cold AND dark not just dark.

I think I posted that I ran onto doing this by accident. While getting ready to install new stovepipe I set the new black flue pipe behind the stove with the elbow end on the floor. The next time I emptied ashes I notice how much air was moving through the pipe from convection. It was pulling cold air from off the floor, not just from near the floor at the level of the stove. The air was being warmed all the way down to the floor now. This allowed better convection throughout the house ( single level ) and the bedrooms were a good 8 - 10 degrees warmer than they had been in the past. The fact that they were warmer was a plus. That they were warmer without the use of electricity was even more of a plus.

This year I changed it a bit. I mentioned how earlier and will spare going back over the details. It works for me. I burn dry wood and my flue temps are still high enough that creosote hasnt been an issue.

Drawing the cold air from downstairs back to the heat source will help regardless of if it is done with or without electricity. The cost of electricity to move the air should still be less than the supplemental fuel needed to heat that living area. Any heat you push down there is going to go directly towards the ceiling and up the stairs. Any cold air you pull from there will be replaced by warmer air from upstairs.

 

[loknlod]

I should have worded my response differently. I simulated a small vent at the crawlspace door by cracking the door open just a bit. I figured this would allow sufficient return (warmer) air to the crawlspace to replace what the hot air pipe was sucking through convection.

If the rooms are vented together, I can't see how I would be drawing cold air through the crawlspace from outside due to a pressure difference. Basically I mentioned keeping the 4' by 4' door open just to give everyone a picture that the crawlspace isn't a sealed off area. The crawlspace already has vents to the main level which add up to 4" by 40" so I am not sure if I will need more venting to stabilize pressure when this little fan is running. The fan claims it can move 80 cfm and I plan to have a resistive type switch so I can regulate fan speed if needed.

If I am missing something, by all means let me know. I wouldn't be asking questions if I had all of the answers.opcorn:

 

[KsWoodsMan]

I follow what you are saying. With the opening into the crawlspace larger than the one the fan is in there should be very little negative pressure to draw in cold air from outside your house.

The lower in the room the opening is the more cold air it will draw. Having the opening downstairs 4" tall and 40" wide at the bottom of the door seems better than 4" wide and 40" tall. Same amount of opening, just it is pulling only the coldest air from the room.

Anything that gets the cold air back to the woodstove will keep you from running the gas burner as much.

 

[loknlod]

Pretty cool! (convection that is)

Temperature is -7 this morning so I am running the stove pretty warm. I decided to see what the draft was at the cold end of the tube. I first tried a match to watch the smoke and that worked ok but the smoke only lasted for a couple seconds when the match was blown out. I saw a spider web nearby and took a long strand of it and hung it in front of the tube and WALLAH, we have suction.

Just thought I would share, if the kids want to learn from this experiment have them use a spider web (maybe even the fake halloween stuff would work) instead of matches.

 

[RatchetJaw]

Ok I see what your saying

You are absolutely right the more cold air to the stove the better . what i was thinking is that this crawlspace was under the house and is probably not sealed up to well from the outside air drafts and such . and in my understanding if that is the case then you might or could cause more cold air in then the stove can keep up with in output Btu's that was my only concern I use a similar method to keep my place warm because my place has a Lopi Answer insert in a zero clearance in what I consider a false wall that the chimney runs in all the way to the roof what i did was drill a 2 inch whole through the back corner of the zero clearance box and mounted my fan blower right to it so not only does it blow through to the back of the stove it circulates all that dissipated heat back out of the zero clearance box from between the two layers and since this false wall has an access in my attic it also works to draw even more of the cooled off hot air back down to the blower for a good second reheating works very well before i did this I could run my stove all day and I would get no heat just a very little through the door. and I have my small blower hooked in with a rheostat so I can adjust the airflow up or down .this stove was in here when I moved in it was already installed they didn't run a cold air intake through the bottom and this is my only complaint it drafts its air from right in the front so it sucks the heat it makes right back out the chimney the zero clearance also doesn't:greenchainsaw: allow for it to vent from outside and I cant modify it to much or it will loose its ability to actually work after I did my fan install I had it inspected by a certified stove tech and had my chimneys cleaned at the same time .and he approved my blower and the location.

 

[loknlod]

The stove has its own cold air intake from outside, that was highly recommended for this model and our conditions. The foundation is sprayed outside which should be pretty air tight. I believe the biggest problem is the idiot who built the place didn't spray the interior walls of the crawlspace to keep the frozen ground temps. from radiating through the walls. The sprayed foundation only goes down to ground level or barely beyond I believe, and the crawlspace continues for about 3 feet below that.

I think the wife and I are going to have a crawlspace rearranging party this spring and then give the insulation guy a call.

 

[KsWoodsMan]

So I wasn't nuts to think the heat from the stove would pull air from the 'room' below it ? All of the air that passes through that pipe was the cold air stacking up down stairs.

-7 thats cold enough that I would have mine cranking. If the pipe behind the stove isn't hot it should be.

If it isnt, can you replace it with a darker colored set ?

Even if you have to add a fan, to move more air than convection allows, the darker color will be more efficient at heat transfer than galvanized.

Have you given any thought to double walling the flue pipe and plumbing the return line to it ?