Does anyone have this wood stove top heat blower to increase BTU output?

Hello

This looks like it really works! Anyone try it?

See story - click here
House Works: Small fan boosts wood stove's heating power

Hot Shot universal stove blower - scroll down to bottom
http://tjernlund.com/Tjernlund_Hearth_and_Ventilation_Products_8500670.pdf

Pic 1 - BTU booster fan

 

First time I have seen that set up....looks like it would work well if your stove did not have a blower or a way to add one as original equipment.

 

That would double the heat if you have a blower by extracting more heat from the top right?

 

Don't really think you could say double but the blowers do help. Your stove is still going to make the same amount of heat but you can move that heat instead of just radiation.

 

True, unless it's thermostatically controlled.....

 

I agree, and it may heat the room faster

 

Do you mean the stove is thermo controlled ???? Wouldn't it still only make so much heat the same as one with manual air controls ?? More air more heat.

 

Yes....my stove heats the room faster with the blower on.

 

Nope, BK has the bimetallic damper, basic thermostatic air control. When my fans are on it takes heat off of the stove fast, ramping up the draft and effictively makes more heat on a given air setting.

Not being contrary or arguementative, just providing insight.

 

Didn't think you were....ditto on my end. Maybe I do not completely understand the Blazeking therm control but it would still only make so much heat even on the highest setting regardless.....right ? You can only feed the fire so much air.

 

Oh no, your stoves can absolutely make more heat with a blower. See, the blowers strip heat from the stove faster than if there was no blower. Kinda like blowing on a spoon of hot soup. This will cool the stove until/unless you increase the burn rate to make enough extra btu to match what the blowers are stealing.

This is how I can burn through a full load of fuel in my nc30 without getting it hotter than 700. Big blowers make a big stove out of a smaller one.

 

There is only so many BTU's in a load of wood and the stove can only be so efficient. What the blower MAY do to increase heat is to SLIGHTLY increase efficiency by extracting more heat from the exhaust before it goes up the chimney. There are limits to how much heat you could be pulling out without a much bigger heat exchanger, and also the loss of draft issues, so in practice the extra heat bump is going to be closer to 1% than 10% and certainly nowhere near double.

What the fan will do is circulate the heat better and pull it off faster. You will get more upfront heat, but it will have less effective thermal mass so you will get less later at the end of the burn to offset that.

 

Without rereading rhe whole thread I don't think "efficiency" was the idea. It was, does it make the stove pump more heat into the room? My answer is YES.

 

Big/good blowers will increase the btu output of the stove and will require you to burn more wood to maintain that rate. Nothing to do with efficiency, it's a matter of how fast can you burn that fuel without overheating the stove. Blowers remove heat from the stove to keep it cool at a high burn rate.

Folks with wood furnaces know that you can remove too much heat with too much blower. I ran into this with my NC30 and aftermarket blower. To solve this problem you install a thermostatic switch on the stove to shut the blowers off when they've been too effective and allow the stove to catch up.

Seriously, my NC30 is down to just coals after 3 hours. That's 3.5 cubic feet of fuel converted to heat. Way more btus have been liberated from the fuel during those three hours than if no blowers were being used.

 

Well on my 30 I put a convection hood across the top as suggested by another member, I also installed 1" thick tight fitting baffles in it. I used the same amount of wood to date as any other year. The increase in heat circulation for me was very noticeable. This using the stock ac100 blower ( I replaced the bearings in that this winter also) I think that blower is only 100 cfm with the hair dryer type at maybe 75cfm. The baffles made a big change in the burn chamber- no dirty glass other than a slight haze much earlier secondaries and a longer run on those and that's with the control about 1/4" from full close. The stove is filled around4:30 am stepped down by time I leave about 5:30, still had coals to restart around 6pm and the 2k sq ft house was still above 65 deg. 98% of the time. Prior years I would have an additional fan running to get more circulation. The cut in point for the ng unit is 65 deg. , that would sometimes be cycling at the 6pm mark and not always enough coals to restart

 

Same number of BTU's, more BTU's per hour. It seems like you would be better off with a properly sized stove rather than trying to increase the burn rate. Sure the stove top won't show a high temp that indicates an overfire, but what about the stove internals?

I can certainly see the benefits of using a fan to get the heat into the room and where you want it quicker and more evenly, but I would be careful using one to push a stove to burn significantly faster than it was designed to.

 

I have often pondered this also.
I liken it to an air cooled car engine. When the engine gets too hot, the external fan will come on, the engine will cool down.
This would include surface temp and internal temp because the fan cools the outside metal which in turn "wicks" away heat from the WHOLE engine.


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With my stove partly recessed in a fireplace, I have found having a fan on the floor blowing cooler floor air towards the rear of the stove helps warm the room faster. It seems to reinforce whatever natural convection currents might already exist. The air flow pulls heat not only off the stove and pipe, but off the fireplace masonry as well. Ten bucks well spent, as long as there is the fan/cord aren't in the way.

 

This whole discussion is why you can't buy a wood stove INSERT without a fan... that I know of....

 

You can't get a bigger stove, and certainly not at a better price. A wood furnace would be a great idea but they are all still illegal in Washington until one drolet model might have made it this year. We require clean burners here in Washington.

The stove internals are exposed to the intense heat of the fire, blower or not. They are also cooled by the air outside and by combustion air flowing through them. Really, looking inside, there aren't many internal bits. Mine are holding up great.