# Duct Work Over Stove?



## Moss Man (Oct 1, 2008)

Does any one here have a plenum and duct work coming off their woodstove in the cellar?

I priced one at the local sheet metal shop the other day, $180. for a square plenum 3'x3' over the stove with two 6"x20' pipes and the elbows. Doesn't sound like a bad price.

My basement is 80 degrees and the upstairs is less than 70 degrees, thus the need to funnel the heat upward.


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## PA Plumber (Oct 1, 2008)

Moss Man said:


> Does any one here have a plenum and duct work coming off their woodstove in the cellar?
> 
> I priced one at the local sheet metal sop the other day, $180. for a square plenum 3'x3' over the stove with two 6"x20' pipes and the elbows. Doesn't sound like a bad price.
> 
> My basement is 80 degrees and the upstairs is less than 70 degrees, thus the need to funnel the heat upward.



Do you have central air in the house?


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## Moss Man (Oct 1, 2008)

PA Plumber said:


> Do you have central air in the house?



Nope, all we have is the large wood stove in the cellar and one propane Rennai heater in the kitchen. Our hope is to not fire up the propane at all this year and rely totally on wood.


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## PA Plumber (Oct 1, 2008)

We get some pretty good convection just by leaving the basement door open.

Would cutting a couple of floor registers in the first floor be an option?


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## Moss Man (Oct 1, 2008)

We have one register just a couple feet from being directly over the stove and we have left the door going upstairs open. The problem seems to be getting the heat to the north end of the house. With the one register and the door open, there just isn't enough circulation going on. The cellar doesn't need to be above 60 degrees, we do very little work down there.


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## PA Plumber (Oct 1, 2008)

Moss Man said:


> We have one register just a couple feet from being directly over the stove and we have left the door going upstairs open. The problem seems to be getting the heat to the north end of the house. With the one register and the door open, there just isn't enough circulation going on. The cellar doesn't need to be above 60 degrees, we do very little work down there.



A warm cellar does give you a warm house. Would you consider cutting in another register, or two, on the north end?

Could even set up a or hang a fan to get the air to move to that end of the basement.


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## Moss Man (Oct 1, 2008)

I do agree that a warm cellar helps heat the house, but having it 80 degrees downstairs and 65 upstairs isn't working out, we end up torching up the propane heater to keep the kitchen warm. Burning propane this year is unacceptable considering I am losing my job January 1st. I still believe funneling the heat through ducts is the best way to get the heat where we need it most.


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## MJR (Oct 1, 2008)

Install a register in the floor of the north end of the house. Place a muffin fan in the resister (cold air return). This should draw the heat north ward if you leave the basement door open. The best of luck to you.


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## Moss Man (Oct 1, 2008)

Thanx guys! TreeCo, I believe I will give that plan a try as it seems logical. I will post the results, it'd be nice to pull this off without throwing money at it.


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## excess650 (Oct 1, 2008)

A possible lower $ way to go might be to use a kitchen range hood with built in fan, and pipe the air to the cold end of the house. Flexible dryer vent hose might work.

You could construct that hood yourself, but will need a fan and ductwork to move the warm air. The hood over the bench in my garage is made from 2x3s and paneling. Fans for computers are low voltage, quiet, and cheap.


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## Rookie1 (Oct 1, 2008)

I know this is kind of different but thought I would share pics. I put Sierra in basement and had HVAC man put stainless liner in brick chimney. While he was doing that he said he would build me hood when he got some extra sheet metal. A couple of months later he called me over to his shop. He gave me hood and 10" pipe for free, hes a cool dude. I had to buy elbows. I cut hole in cold air return and connected. Now I turn on furace blower and it pulls heat off stove. I know its not 100% effiecent but it keeps furnace off till its around 20 degrees f. 










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## buildmyown (Oct 1, 2008)

Rookie1 said:


> I know this is kind of different but thought I would share pics. I put Sierra in basement and had HVAC man put stainless liner in brick chimney. While he was doing that he said he would build me hood when he got some extra sheet metal. A couple of months later he called me over to his shop. He gave me hood and 10" pipe for free, hes a cool dude. I had to buy elbows. I cut hole in cold air return and connected. Now I turn on furace blower and it pulls heat off stove. I know its not 100% effiecent but it keeps furnace off till its around 20 degrees f.



I like it and wanted to do something similar 2 questions do you have any trouble with the hood pulling smoke threw the house and how do you wire it so just the blower will come on and not the burner. I have an oil forced hot air system and my cold air return runs right over my wood stove so taping in wood be very easy.


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## Rookie1 (Oct 1, 2008)

Yes it will pull smoke if chimney is getting plugged up and you get a little puff of smoke whan you open door. Next Im not HVAC savvy but I have oldstyle round thermostat. It has two levers,one on left says cool/off/heat,one on right says fan on/auto. If I put left lever on heat set thermostat to say 68 then turn right lever to fan on It will run blower with no furnace till temp goes below 68,then burner comes on. I also have oil with central air too.


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## PA Plumber (Oct 1, 2008)

buildmyown said:


> I like it and wanted to do something similar 2 questions do you have any trouble with the hood pulling smoke threw the house and how do you wire it so just the blower will come on and not the burner. I have an oil forced hot air system and my cold air return runs right over my wood stove so taping in wood be very easy.



I just cut extra returns near the wood stove. Put in the Hart and Cooley ones with a damper. Open the dampers in the winter and close them in the summer.

When the outside temp gets into the mid to low 20's F, I just turn on the fan to circulate the warm air better.

Does a great job down to the single digits.

The thermostat for the oil will still kick on if it needs to.


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## buildmyown (Oct 1, 2008)

Rookie1 said:


> Yes it will pull smoke if chimney is getting plugged up and you get a little puff of smoke whan you open door. Next Im not HVAC savvy but I have oldstyle round thermostat. It has two levers,one on left says cool/off/heat,one on right says fan on/auto. If I put left lever on heat set thermostat to say 68 then turn right lever to fan on It will run blower with no furnace till temp goes below 68,then burner comes on. I also have oil with central air too.



Excellent all I need to do is change out my t-stat and do a little wiring and be good to go.



PA Plumber said:


> I just cut extra returns near the wood stove. Put in the Hart and Cooley ones with a damper. Open the dampers in the winter and close them in the summer.
> 
> When the outside temp gets into the mid to low 20's F, I just turn on the fan to circulate the warm air better.
> 
> ...



I already have a couple extra vents over the stove and they do a great job of bringing the hot air upstairs into that part of the house but the end where the bedrooms are can get a little cool at night. BY doing this it will be nice to kick the blower on for awhile and brin gthe temp up in that end of the house.


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## Rookie1 (Oct 1, 2008)

When I moved into house it only had old oilburner with that Tstat. Then had HVAC guy install a/c and he was able to use it. Im not sure why it was wired that way origanally but im glad it was. The other bonus is it circulates the air in the house.


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## winsormcbeth (Jan 7, 2013)

buildmyown said:


> I like it and wanted to do something similar 2 questions do you have any trouble with the hood pulling smoke threw the house and how do you wire it so just the blower will come on and not the burner. I have an oil forced hot air system and my cold air return runs right over my wood stove so taping in wood be very easy.



My cold air return from my furnace runs directly over my wood stove in the basement too and i thought about running duct work from a couple feet over the stove and connecting it to the return but someone said you shouldn't do that because it can through the system out of balance? Did you do it? I'm also thinking about putting a hood directly over the stove like Rookie1 did and then running duct work to the center of the house upstairs.


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## openloop (Jan 8, 2013)

You need a single LARGE vent through the floor as close to directly above the stove as possible. Then a smaller vent in EVERY other room and hallway in the house. The warm air from the stove will push directly up the large vent and all other vents will act as returns. The natural convection WILL move the heat through the house as long as the vent above the stove is large enough, and will force cool air back down the returns to keep the lower level cooler. Attempting to force hot air upwards in any spot other than above the stove will impede the natural convection. I have a stove in the basement below my living room with a single large vent and routinely get 125 degree air flowing upwards through the vent while the returns see a 60 degree downdraft back into the basement keeping it livable.


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## Chipperhead (Jan 12, 2013)

*Negative pressure*

Greetings all:

Just a quick note.

From the standpoint of an old ductman, we have to be very cautious when ever we place any fan intake in the same room as any appliance that is connected to a chimney. In fact, it is against code. Any negative pressure created by the fan will work against the chimney draft. That's why return openings are not permitted in furnace rooms.

I remember my first season heating with wood.  Got some smoke in the basement, so I opened a window and put a box fan blowing out. The longer I ran the fan, the smokier my house got. LOL I can't believe how long it took me to figure it out. 

Take care,
Marty


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## Vibes (Jan 12, 2013)

I'm installing a new gas furnace in my house as we speak. I'ma sheetmetal worker by trade, but not a control guy at all. My bud who is the service teacher at our school is the guy who got me the furnace. I asked him about tying the woodburner into furnace duct and he told me its doable, but complicated. 

He told me that with these new dual stage furnaces its really important to size the furnaces to the living space. He even has a formula that takes into account how much of the house is facing north and south and divided by the number of windows on each side. He said my house size was really close to the differance of an 80 ton to a 100 ton unit. I said I would rather just go with the 100 ton and he said you shouldn't just go oversize on the furnace like you could with the old 80% furnaces because the furnace shouldn't be run overheated. Its bad for the computer on the furnace. My head was spinning. 

From what he was explaining to me, if you have a newer gas furnace or heat pump, its probably better to seperate your duct work for the woodburner. I would definately keep it away from the return duct. He also told me that the extra $380 that the dual stage furnace is gonna cost will be made up in gas savings in a little over a year.


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