Good Air Circulation

[rouxzy]

Just a quick note for those of us who fight to get some of that nice hot air in the cellar distributed upstairs where we really want it. Unless there is a cold air return, then point the box fans, the in line fans, the register booster fans, and even the fans on our stoves at the wall. Because in essence without a cold air return that is pretty much what we are doing. I have bought and done it all, but until I finally put in a cold air return nothing worked. I live in a 200 year old farm house. With the stove in the cellar I'm keeping my 2 second story bedrooms at a constant 68 degrees, and this is with a 4 inch duct and this is with the recent sub zero temps. I have burned out in line fans bought booster fans and nothing worked until I hooked up a simple duct line from a floor vent on the first floor to my fan on the back of the stove. Actually I got flexible duct and virtually wrapped it around my 135 cfm fan on the back of the stove and ran the other end to the floor vent. If you stand by the vent you can feel the cool air rushing down and I can feel the hot air at the other end in the bedrooms. My first floor was a steady 72 with this system until I did some other things, now I'm at 76, (my wife's comfort zone), most of the time, but that is another story. Bottom line is unless there is no air returning there will be no air going up. Good luck.
Tom

[BinghamtonNY]

Good advice. Everyone with problems moving air should read this. Deserves a BUMP...

[WNY]

Check out my cold air returns to my furnance, 12-14"+? The furnance is older Janitrol Convection Style (No blower) and the hot air circulates very well in the first floor! Pretty even heating. One nice thing, it is very quiet. Except for the cast heat exchanger expanding when it gets hot. They do work!

http://nepacrossroads.com/files/furance_476.jpg

I think I will tap into them for the coal stove with some flexible 4" duct, since i have the stove hooked up where it goes up thru the floor.

[coalkirk]

Dave,

That 4" vent pipe in the picture looks like a really long run. There is stuff coming out of the joints and it does not appear to have adequate rise to the chimney. I assume that's a water heater vent? Have you checked the draft on the water heater at the draft hood? I'm not trying to be knit picky but I see similar senarios often that are producing serious carbon monoxide levels in folks homes.

Kirk

[WNY]

Kirk,

Thanks for your concern, already changed out to an electric hot water tank, that pipe was rotted out and mostly removed now!!

[LsFarm]

Many years ago, I had a tri-level house with hot water heat. I added a family room and garage to the house, making it a very long house. And I added a wood burning stove at the far end of the family room to help with my heating.

I couldn't get the hot air out of the family room, it would be 80-85* and the upstairs bedrooms stayed at 55*. I tried box fans on the floor for return air and a few fans on the ceiling. This helped to raise the bedroom temps to 60*.. Not much help.

In the bedrooms I cut cold air returns into the floor joist spaces, connected them to a ductwork that ran under the floor of the ground level part of the house and under the floor of the family room. The ductwork ended behind the wood stove.

With only a small in-duct floor-grate fan, I was able to get the air to circulate well enough that the family room was at 75*, and the upstairs bedrooms were at 68-70*, A huge improvement.

Even with open doorways and stairways the house needed ductwork to get good airflow.

Greg L.

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[jimbo970]

just so I have this straight rouxzy,

you have connected the flex pipe from the vent upstairs that you want to draw the cool air down to the fan motor that provides air to the stove to keep the coal burnin?

[rouxzy]

Jimbo970, on my Harman Mark III there is a fan than blows through a baffle system in the stove to extract heat. I have a hand fed stove so there is no fan to burn the coal. If you stand in front of the stove there are two ports that hot air blows out of it.
Tom

[traderfjp]

This is a very interesting thread. I'm still a little confused on how to setup a cold air return for my house. Maybe you guys can help. I have an Alaska Channing 3 stove on my first floor. The stove is mounted in a corner at one end of the house. The room is fairly open but the temps are around 77 for the stove room and around 69 upstairs. I have a fan at the top of my stair well to suck (reversed direction) some of the air to the upstairs. I'd like to moderate these temps some. Above the stove is my daughter's bedroom. If I put in a register, above the stove, I'm assuming I would get some of that heat upstairs. To do a cold air return would I also need to put in a second vent and run a duct or pipe to the back of the stove? I could probably do this through the wall. My goal is to also warm the other bedroom so would it be better to run a vent to a central location and then run a cold air return, from upstairs, to the back of the stove? Does the return have to go to the back of the stove? Any advice is appreciated. Thanks in advance.

[rouxzy]

Traderfjp,
My understanding of air flow is if you want the warm air to go where the cold air is then you need to get the cold air to where the warm air is which will cause the warm air to replace the cold air and vice versa. So, yes if at all possible have the cold air return dump to the stove.
Tom

[LsFarm]

Hi Tom, have you upgraded the 4" duct to a larger size, or do you feel the 4" is good enough?

Did you use 4" clothes-dryer vent or galvanized duct piping? What was the cost of the duct and how long was the run??

Thanks, Greg L

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[rouxzy]

Greg,
No I have not upgraded the 4" yet but I will be going to a 6" line shortly as I have just opened up some walls in a remodeling job in the house. I'm just using dryer type metal hose by may go to an insulated flexable duct when I do a more permanant fix.
Tom

[pjb153]

I realize this is an old thread, but I wanted to revive it to get some more feedback on the subject.

I am currently facing some ducting issues and I have the basics all set up to run the hot air into my first and second story living space.

I own a cape cod with an addition. The addition sits above a garage which is not heated. My stove is in my basement and I need to push heat to the original dining room directly above the stove as well as the addition which I am crossing thru my original block wall and running about 4ft to a floor vent.

I could run a cold air return from the far end of my addition which is 26ft away from the hot air register (basically straight accross the room). With the garage not being heated, should I insulate the cold air duct.. or do you think the air temp will not get extremely low. I imagine my garage temp could drop to 30's.

Also I may want to revamp my hot air ducted to get more air flow, possibly use larger duct and go with an 8" pipe or rectangle.

another question would be.. is it better to enclose the entire convection motor in a sheet metal box? it may help my motor run cooler as well.

Thanks

[LsFarm]

Insulate the 'cold air' return wherever you can, it loses a lot of heat to the surrounding spaces.. especially a cold garage space.. the 'cold air' is not really that cold,, probably 65*, so you don't want to give up that heat to an unoccupied garage..

You must create a circulation loop, cold air pulled from a room will be replaced by warm air.. just pushing warm air into a room is a dead-end,, you have to provide an exit for the cool air, then the warm air can enter..

Greg L

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[pjb153]

I think I will first try the duct uninsulated, the reason is.. if a little warm air gets into my insulated gargage, that is not a bad thing.. we park in there, the coal is in there, I am often in there working. if the temps in the duct drop that much I will insulate, but first would like to see what it does. Baby Steps..

Here are some photos. i need to rework the ducts from the stove to hook right from the front and go larger, maybe 8" pipe. I need to calculate how much area I need to match my 265 cfm blower. If I run an 8" pipe off the hood of the stove, i will carry that to an 8" to 4" or 6" Y, then to the floor registers. let the greatest distance of duct be 8".

My cold air return, I will be using a 4x9 oval duct, giving 36 sq inches, lead that into a 6" round to hook into my blower.

Here are some snapshots. Sorry for the cell phone quality. You can see how the design is restricting the flow by taking the pipe 180 degrees towards the back. i can use the same hood, just cut my scoop in the front.