Attic duct/fan to circulate wood-stove heat.

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Old 10-05-06, 08:35 AM
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Attic duct/fan to circulate wood-stove heat.

Winter is coming on and we heat quite a bit with our woodstove. I would like to get that heat to circulate better (into two bedrooms). The house has a forced-air heating system, but the t-stat no separate control on the fan. I see two options...

(1) Change controls so I can just run the fan on the forced-air system. I am a little skeptical, since the cold-air return is not real close to the woodstove.

(2) Run a circulating fan/duct in the attic from nearby/above the woodstove to the two bedrooms. The run would be a straight-shot roughly 30' to a Y with maybe 3' legs (even). In my old house I vented a new bath with a Fantech inline fan. It could move A LOT of air (even with a couple of bends in about 20' of ducting). I think it was rated for "continuous run." Considering the same product, used here with insulated duct-work.

Obviously, (1) is probably cheaper but I suspect it won't draw enough warm air to be effective. I may start here. Is (2) feasible? We live in Wyoming, so the duct-work will be in a cold attic. Can it be sufficiently insulated (and how) to not lose the heat?

Thanks!

Nick
 
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Old 10-05-06, 10:49 PM
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Id start with #1. You dont say what furnace you have, new or old . You can put a new tstat in with the fan switch on it. If the furnace dont have a relay for fan you can add one to it. On some older furnace with a fan limit control on them you can turn the blower on there. Id stay out of the attic up where you are . With any heat pipes.

ED
 
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Old 10-06-06, 07:00 AM
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Thanks for the reply. The furnace is a Lennox from 1995 (I don't know what model right now). I think I will see how it goes with running it's fan. It would also be nice to change controls so we can control our humidifer from the same unit.

As for the other idea: You don't think it could be insulated well enough? I was thinking about insulated ducting laying in the blown-in stuff, then with fiberglass laid over that.

If I have air at 75 - 80 F moving quickly (150 CFM in a 6" round duct) for 33' through an insulated ductwork (R??) in a 32 F attic, what temperature does it come out at?

Surely, there is a magical HVAC formula that would answer that. Or, not?
 

Last edited by nvisser; 10-06-06 at 07:32 AM.
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Old 10-06-06, 08:09 AM
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A 6" round is good for 100 cfm in metal slower in flex. if you put the pipe in the attic use the silver flex duct kind . So it will last.
so we can control our humidifer from the same unit.
Its control should be on the furnace return. So anythime the fan is on the humidifer can run if need be.

ED
 
 

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