Returning Cold Air To Stove Room

[Sain6815]

I know this has been discussed in the past, but I'm looking to add a register in the "eat-in dining room" on the main floor of my house that utilizes an inline 8" duct fan to push cold air into the room in the basement with the wood stove.

I'm going to add an antique cast iron 12"x14" grate in the living room above the stove that can let warm air rise. I know fusible dampers and all that are required. My hope is that this will promote circulation and force the hot air up the grate.

I'm just wondering who has tried this method. I know it's better to push cold air towards the stove and then allow natural convection to do its thing.

 

[WoodyIsGoody]

I know this has been discussed in the past, but I'm looking to add a register in the "eat-in dining room" on the main floor of my house that utilizes an inline 8" duct fan to push cold air into the room in the basement with the wood stove.

I'm going to add an antique cast iron 12"x14" grate in the living room above the stove that can let warm air rise. I know fusible dampers and all that are required. My hope is that this will promote circulation and force the hot air up the grate.

I'm just wondering who has tried this method. I know it's better to push cold air towards the stove and then allow natural convection to do its thing.

That will help but...

If the air rising through the grate is 85 degrees and the air collected by your powered duct is 62 degrees, you have a 23 degree temperature differential. An 8" duct fan will be limited in how much air it can move by the 8" duct. If there is room for a larger duct it will move a lot more air and make a much bigger difference. If your application is typical I would be thinking more along the lines of a 12" duct but even a 10" would move a lot more air than 8". And with a relatively small temperature differential you're not going to be moving many BTU's with an 8" duct.

 

[begreen]

It doesn't take a huge or rapid exchange of air to move the heat. A 240cfm blower will do nicely. Connected to a 6" duct it will easily accommodate a 20 x 15 x 8' room with an air exchange every 10 minutes. Several folks have used this setup successfully. The quiet Panasonic FV-20NLF1 works well for this configuration. You could go up to 8" insulated duct if the run is long, but for <30' 6" round would be sufficient.

 

[WoodyIsGoody]

It doesn't take a huge or rapid exchange of air to move the heat. A 240cfm blower will do nicely. Connected to a 6" duct it will easily accommodate a 20 x 15 x 8' room with an air exchange every 10 minutes. Several folks have used this setup successfully. The quiet Panasonic FV-20NLF1 works well for this configuration. You could go up to 8" insulated duct if the run is long, but for <30' 6" round would be sufficient.

I probably should have elaborated a bit. Certainly an 8" duct can move enough air to get the job done but, the more air you want to move through it, the higher the velocity it will travel (noise) and the more electricity it will consume. You could reasonably move 400 cfm through an 8" duct but the sound levels would not be acceptable to me. Remember, this is not like a bathroom fan that you only run for 10-15 minutes. During heating season it will be on whenever the stove is burning. If you value peace and quiet, and most wood burners do, you want the air to be flowing easily through an appropriately sized duct with big enough grills that it's not creating a distracting whoosh.Of course if there's not room for a larger duct you wont have a choice. And avoid any duct that does not have a smooth interior.

 

[begreen]

Yes, most folks go for a lower cfm blower and/or put a speed control on the fan. That makes for whisper silent operation.

 

[Sain6815]

@WoodyIsGoody and @begreen thanks for the advice!

I'll probably roll with the 6" setup. I also have the basement staircase door which also opens into the living room. So I'll also get some heat climbing and circulating this way as well. Just looking for an additional boost.

 

[begreen]

@WoodyIsGoody and @begreen thanks for the advice!

I'll probably roll with the 6" setup. I also have the basement staircase door which also opens into the living room. So I'll also get some heat climbing and circulating this way as well. Just looking for an additional boost.

If you can post a floor plan that shows locations of the stove, stairwell, etc. it may help visualize options. If you opt for 6"r duct I would go for the lower power Panasonic FV-10NLF1 or equivalent.

 

[Sain6815]

Here is a rough sketch @begreen . Hopefully this helps. Fan will be located in the duct that will run through wood shop. Not super worried about sound level in there.

 

[begreen]

Yep, that looks like it will help move the heat across the house and will encourage convection up the stairwell.

 

[WoodyIsGoody]

@WoodyIsGoody and @begreen thanks for the advice!

I'll probably roll with the 6" setup. I also have the basement staircase door which also opens into the living room. So I'll also get some heat climbing and circulating this way as well. Just looking for an additional boost.

You would probably get pretty good natural circulation just putting a floor grate by the island without a fan. I would also want to be able to open and close it.

 

[Sain6815]

Will hopefully be adding this vent on Monday evening. It’s been in the 70s here in SC! Not complaining one bit, cause I love this time of year.

I do have an office that’s located behind my stove where the staircase is located. The heat is definitely 5-10 degrees warmer in the den than the office. Then the upstairs is about 5 degrees cooler than the office. So lots of heat staying in stove room.

My plan is to add the register return to stove room as mentioned and to place a small table fan on the floor of the office blowing towards to stove room.

Hopefully the use of the table fan and return vent will force more heat into the office which will force more heat up the stairs into main living floor.

Thursday is our next colder night so I won’t fire the stove up til then.

 

[Sain6815]

Added the duct and vent today. Got cold air returning from dining room to basement den. Also added a box fan on the floor of our basement office blowing towards den.

So far it’s working! First time I’ve accomplished a temp increase upstairs. Went from 68 to 70 while outdoor temp dropped to mid 40’s. Tomorrow evening will be below freezing so we will see what happens then!

 

[venator260]

A similar set up is currently keeping me warm. My living room would get rather cold and there was a large temperature difference between that room and the kitchen/dining room where the stairwell came to.

There was already a vent in the living room, I just put a fan below it blowing into the basement. Air already flowed downward naturally, the can is just speeding up what was happening already. This set up brings more heat up the steps and keeps my living room warmer.

 

[Sain6815]

A similar set up is currently keeping me warm. My living room would get rather cold and there was a large temperature difference between that room and the kitchen/dining room where the stairwell came to.

There was already a vent in the living room, I just put a fan below it blowing into the basement. Air already flowed downward naturally, the can is just speeding up what was happening already. This set up brings more heat up the steps and keeps my living room warmer.

I was skeptical about how well blowing cold air towards the stove would work. Seems counter intuitive, but it really works!