forced draft wood heaters?

[saichele]

Are there any forced draft wood heaters? I'm thinking of something essentially like a pellet stove, but for conventional cord wood. Seems like a natural for furnaces.

 

[elkimmeg]

I admit I guessing here, so if wrong please correct me. With oil fired or automatically fired appliances drafts are constant Or if oil or gass before the fire box is ignited the power vent system is activated prior to firing. and x amount of time after ignition cycle is completed.

The problem with wood stoves is there is no constant. No set vollume and it varries with every split burrnt. It would be very hard to regulate the draft without a constant induction.

Craig woulld be better at explaining wood stove draft enhancements, I do believe they exist., But I have no experience with one. Is there a turbine type, that manually regulates draft like venting old barns?

Btw great topic for those that live in a valley and never can get the draft to run their stove effeciently

 

[smirnov3]

One thing I've wondered about is why nobody puts forced draft on masonry heaters: That way, you could extend the exhaust train & extract even more heat & get higher efficiency (With a passive draft, you have to leave some of the heat in the exhaust gas to get it to rise out of the house).

 

[Martin Strand III]

One thing I've wondered about is why nobody puts forced draft on masonry heaters: That way, you could extend the exhaust train & extract even more heat & get higher efficiency (With a passive draft, you have to leave some of the heat in the exhaust gas to get it to rise out of the house).

See my post today under Masonry Heaters.

Aye,
Marty

 

[saichele]

I guess where I was going with that was that the passive draft systems seem fairly haphazard. In addition to construction issues, you get all manner of atmospheric effects. If you had a sealed firebox (and flue - no escaping gases) it would seem relatively straightforward to rig a couple temp sensors to keep a fire going, then when heat is called, dial up the airflow to juice the output, and likely the efficiency. Also seems like a decent way to keep a boiler from smoking excessively.

Steve

 

[webbie]

Wood gasification Boilers use forced draft in order to gain high efficiency. See, for instance:
http://www.woodboilers.com/wood-gasification.asp

Such boilers usually run at full bore and the heat is transfered to storage tanks. They do not have an adjustment as to output....only full or idle.

As far as these systems for space heaters, my guess is that it would make it too complex and rely on electric - and why do it when they have solved the problem with cats and non-cats?

It might work for masonry heaters as either an easy startup or added benefit (after burner).

 

[laynes69]

My wood/coal furnace has forced draft installed on it. And truthfully I haven't seen much of a difference when its running. Maybe im wrong, but I feel the air should or some should come up under the grates to feed the fire. Where its located now, it runs air on the sides of the firebox from the rear of the stove. I think its acutally better to not have it running because of where the air comes in when its not running, is where the flames go up the back of the firebox. When the 2 meet, I get great secondary combustion. I do feel when it runs, its cooling off the firebox a bit, maybe a thermometer would tell the truth. I feel that I get better results without it. I still have it set at 72 and my LP furnace is set at 67, which hasn't ran once this year. If a woodstove was set purely off of forced draft, I think it would cycle like an OWB. I do have a barometric damper, so maybe thats why I don't see the results.

 

[stoveguy2esw]

i would think that it would have to be an inhanced negative draft system similar to that of a pellet stove, but it should also have a natural convective chimney as well due to power loss issues. this could be ugly if a direct vent positively pressurized firebox with 30 or 40 lbs of wood were to suddenly lose its mechanical draft. as for the induced draft on the hotblast furnace, i would think it would not make a huge difference as the blower size on them is not very big and in order to move air through the stove it would in effect have to push it out the chimney faster than the natural draft is doing so already, so the effect it would have would be a slow building change that would not be as easy to see just watching the fire.

 

[smirnov3]

My wood/coal furnace has forced draft installed on it. And truthfully I haven't seen much of a difference when its running.

I do feel when it runs, its cooling off the firebox a bit, maybe a thermometer would tell the truth. I feel that I get better results without it.
.

If your fan is cooling off the stove, then you should throttle back the fan.

If it's an AC fan, buy a cheap rheostat & plug the fan into that. then tweak the power until you get good flames without a temperature drop.

 

[laynes69]

The forced draft is just designed wrong. It hasn't kicked in for a while due to the furnace keeping up with heating demands.

 

[webbie]

Just blowing air into underneath the grates or firebox does not do it. Look at the cutaway of the Tarm and other similar units. Consider a wood stove like a car - look at how complicated fuel injection is with just the right amount of everything.

It takes careful design to use forced air injection properly.