Does anyone have a house fan blowing air on their woodstove for better heat transfer?

NewtownPA said:

I've been thinking about this today and I'm going to try it when I get home tonight. I'm going to aim a standard house fan to blow air on the front of my Avalon Rainier insert and see if it makes the room hotter. There is a built-in automatic fan which circulates air around the stove and blows it out the top/front, but the air speed is rather slow in my opinion.

Can anyone think of any drawbacks to this?

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First I don't believe blowing a fan on your insert will do much of anything. If if did, I believe it would actually over cool it. The built in fans are designed to extract just the right amount of heat without over cooling the stove such that it begins to loose it's ability to meet EPA numbers. If the goal were to keep the thing cool and pull ALL of the heat out, we'd put them in liquid to pull all the heat out. That's what OWB's do and they pollute like mad.

The amount of air on your Avalon may not seem like much, but I don't think more would be better.

NewtownPA said:

I've been thinking about this today and I'm going to try it when I get home tonight. I'm going to aim a standard house fan to blow air on the front of my Avalon Rainier insert and see if it makes the room hotter. There is a built-in automatic fan which circulates air around the stove and blows it out the top/front, but the air speed is rather slow in my opinion.

Can anyone think of any drawbacks to this?

Click to expand...

I'd be willing to bet that the heat is coming off of your insert just fine with the stock fan. Put a chair in the middle of the room and stand on it, you'll probably find that the top half of the room is much warmer than the bottom half.

A ceiling fan will probably do wonders, or maybe even the house fan pointing at the ceiling to stir things around a bit.

-Hal

I use a 6" low speed fan to circulate air. I do not direct it at the stove. I have it on a shelf about 5 1/2 ft off the floor, on a long wall pointed away from the stove and slightly downward. This helps circulate the air near the ceiling that is warmer to the cooler areas of the house. Works great. I would think that a fan pointed at the stove would stop the natural flow and mechanical flow from the stove. Cooling is one part, but blocking the built in heat extraction will reduce the efficiency of the stove. I chose a quiet run fan, so I barely know it's running. When it's real cold outside and the stove is cranking, walking in front of the fan is a warming exerience.

If you have the space (which I don't) a ceiling fan can do wonders to help move this air. Search the archive for many threads on this topic.

I am up to three fans to try and heat my poorly insulated home with an insert. The insert fan which doesn't blow your hair back but does move heat from the stove, the ceiling fan which prevents the rooms from being top hot and cold low, and then a single pedestal mounted circulation fan blowing air through a doorway to heat the second living room which is a converted garage and due to the insulation on that wall is normally 10 degrees cooler than the stove room.

Three fans is all I can take whirring, humming, buzzing, etc. around the house. My single pane windows and long skinny single floor construction make heating the extremities difficult.

Insert fan required to get heat out of fire, ceiling fan required to somewhat keep the air moving, and circulation fan helpful to send heat to where it's cold.

I've probably posted this a dozen times already, but yes...adding a fan to my insert turned it from a radiant room heater to a convective whole house heater. IIRC, it's 12" diameter and about 200cfm. At 200 cfm, that changes the air in the entire house about once per hour. To me, radiant heat is fine if you have a source in every room...floor heat, radiator, baseboard, etc. No one would expect an central electric or gas furnace to kick on and heat a house with no air flow, but when the fuel turns to wood, it seems like some people expect it to. I also think the the fan cooling effect is much less of an issue with modern stoves...all the primary and secondary combustion happens in an insulated fire box and by the time the flue gases are exposed to any metal surface of the stove, all the combustion should essentially be done. I've only got 13' of flue, but even forcing 200cfm, I don't notice a loss of draft or secondary combustion.

Corey

I ad a small 8 or 10" fan blowing INTO the built in fan intake on my insert, and it heats a LOT better.

Over the summer with downtime, I may upgrade the internal fans to move more air.

I have an airtight in a 600 ft2 room with 24 ft peak, I have a pedastal fan that blows on the stove but I don't turn it on until the stove is really going well. It probably extracts about 1/4 to 1/3 more heat from the stove in my application.

slowzuki said:

I have an airtight in a 600 ft2 room with 24 ft peak, I have a pedastal fan that blows on the stove but I don't turn it on until the stove is really going well. It probably extracts about 1/4 to 1/3 more heat from the stove in my application.

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Just curious, with a freestanding stove, where do you think the heat is going if not into the room, without the fan? Is it possible that rather than getting more heat off of the stove, the fan is helping to get heat off the stove _faster_? I can't argue that the room will heat up faster with a fan pointed at a stove, but it should also mean that you get useful heat from the stove for a shorter amount of time, unless I'm missing something.

-Hal

Hi guys,

I have 2 fans running; one in the hallway to move the hot air to the bedrooms and 1 straight above the stove (6 ft up) on the wall (corner install). This last fan has done wonders; it takes all the heat rising up from the stove and blows it throught the house. The room the stove is in is noticably cooler (75-80) and the rest of the house is much warmer (68-72). It has made all the difference.

Whether your fan will extract more heat, remains to be seen. I also have the Quadrafire blower on my stove and I rarely use it. It helps a little bit when the stove is first coming up to temperature (heats that back room nicely), but when the stove is really going, it makes no difference. The radiant heat of the stove heats that room nicely. The add'l heat rising from the stove, is blown away quickly through the house.

Near perfect setup for my layout. Hope it helps to assess your situation

carpniels

Without the fan more heat is going up the stack, I can pull the stack temp down about 100 F with the fan pointed at the firebox. I just don't want to pull it too low during startup.

slowzuki said:

Without the fan more heat is going up the stack, I can pull the stack temp down about 100 F with the fan pointed at the firebox. I just don't want to pull it too low during startup.

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do you clean your stack once a week to reduce cresote accumilations? the cooler that stack runs the quicker creosote builds up

Its ok I have concast

https://www.hearth.com/econtent/index.php/forums/viewthread/6153/

As has been mentioned you are better off to try and move COOL air into the WARM room and let natural flow take care of the rest.
Since I played around with some fans the first floor heating is much more even, the second floor has never been an issue.

Pictures/sketches help abundantly.

I think the size of the stove compared to the fan or air blowing around it varies. I used to have 2 300 cfm fans on my wood furnace, I now have my gas furnace blower removing air from my wood furnace in series. Our air temps are lower coming from the registers, but its easier to heat our house than the 2 small blowers. We don't get alot of accumulation in our flue or our chimney, and we get secondary combustion in the woodfurnace at all times. It removes the heat from around the firebox, but it doesn't cool the interior like a water jacket would. Our flame baffle and walls of out firebox have white powder on them, no shiny creasote. Your blower size should be determined by the size of the stove. Our furnace has a large firebox so we can capture alot of heat with our furnace blower. Our air on average is 110 degrees from our registers. Plus our blower runs almost 24 hours a day. Its set for 140 on and 85 off. As long as we have a fire the blower is usually running. I have read somewhere on here that airflow can almost insulate a firebox. Our firebox is steel so as fast as the heat is coming off the firebox the heat is removed with the blower. Its just like a gas furnace, but the firebox is the heat exchanger, not the gas tubes. Works well for us.