Source
r/woodstoving•
MJGSimple

Can a woodstove with a fan overfire?

So, I put a fan behind my stove to circulate the air more and the surface temperature of my stove dropped a lot. Even during pretty solid fires it never got as hot as it usually does. I still adjusted the intake by eye, but kept an eye on the surface temps.

So basically, if I have the fan on the stove can I still overfire it? I always assumed the main concern of overfiring is the metal overheating/for a prolonged period, so with the fan it basically will cool off faster and never really get that hot. So can stoves with fans (built-in or otherwise) overfire?

Posted Mar 10, 2022, 12:17 AM UTC

521
[deleted]•

Get a flue thermometer. They should be installed about 18 inches up from stove top. That's probably the best way to monitor temps and prevent an overfire. If you're running a fan or blower the surface temp will be cooler than without. A stovetop thermometer is a little useless IMO. Make sure to get the right kind. If you have double wall pipe you'll need to get the kind with a probe.you don't want to go above ~950 for an extended period. Anything higher and your stove will probably be glowing.

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MJGSimpleOP•

So inside the flue shouldn't be over 950?

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[deleted]•

I wouldn't go above 950. It can handle it for short periods but 950 gives you a bit of a buffer and anything higher and you're risking damage to your flue. Also, the readings aren't instantaneous, especially the non digital ones. The digital ones you can set an alarm. Hope this helps.

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spsanderson•

Yes you can

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MJGSimpleOP•

How so?

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spsanderson•

If the fire is burning to hit a fan isn’t going to cool it down, keep the surface about 400-500 and you should’ve fine

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MJGSimpleOP•

So if the fan is cooling the surface temp below 600, the stove is fine? No matter how big the fire is?

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spsanderson•

Might be, not sure why you would want to over fire though, I don’t recommend it.

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ol-gormsby•

It's not a good idea to have a fan pointed directly at the stove itself. Either mount the fan high and pointing out of the room where the stove is located, or mount it low in another room, pointing to the entrance of the room where the stove is located.

You're either moving warm air out and into the rest of the house, and thus bringing cooler air in to be warmed up, or moving cooler air in and forcing warmer air out into the rest of the house.

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reddit_username_yo•

Pointing a fan at the base of the stove to blow colder air on it is actually the most effective way to increase convective heating. Typically you'd set it up in the doorway of the room with the stove, pointing at the stove.

Cold air is denser than hot air, which lets the fan move a larger mass of air in a given amount of time. This also helps the stove use unheated/less heated air for combustion, as well as reinforcing the convection of the stove.

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MJGSimpleOP•

Thanks for raising this.

My stove has a couple layers of outer decorative metal that has openings for air to get in and around the stove so it's not really directly at the stove. It's basically behind the stove on the floor and the air goes inside the back panel around the stove and out the top. It's also not like super cold air since it's basically around the stove.

You can usually feel a bit of air circulating on its own but I wanted to increase it.

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middleborder41•

You need to worry about the chimney temp more than the stovetop temp. That said, I do find that my fan (mounted/integrated) running on high will help bring the temperature of the stove and chimney down if/when it goes over the preferred temperature zone.

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MJGSimpleOP•

Yeah, I mean, the exterior of the stove being colder means the heat inside the stove has somewhere to go that isn't up the chimney. Hence my question.

I've never measured the temp inside my stove pipe, but the exterior has basically never exceeded 450/500. No idea how that correlates to the inside temp. It is single wall though. I figured I basically want to keep it above 212 but below 600, like my stove. That's what I aim for.

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BotWoogy•

Don’t get me started on fans, but. An integrated fan can really suck the heat off of the unit. But that doesn’t reduce the temp in the exhaust.
If you want to push it to the limits make sure to have the fan on for sure. I recommend an adjustable smart fan like the one I have by AC infinity.

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