flue damper

[j.w.young]

Hi again, I'm about to install a used wood boiler with a forced draft blower. The smoke pipe is 6" dia. Should I include a cast iron damper? I have been burning wood since the 60s but this is my first "forced draft" wood burner. It seems like a useless thing since the fire will be controlled by the size of the blower's inlet & the on/off of the aquastat. I'm going to run the pressurized wood boiler to a 1" fphx to a 800 gal unpressurized buffer torage tank to a 1" fphx to the gas boiler's primary loop. All 1" lines not longer than 30' , not more than 9' of height, ups15-58 pumps & very few 90* elbows.

 

[Duetech]

My experience with dampers is to restrict flow but force a better conservative burn from the wood. If you have an un damped blower and you have the damper available it shouldn't hurt to put it in but it would probably be better to get an auto damper controlled by the aquastat. The auto damper would only limit "post blower shut down" burning. Obviously burning wood as long as you have, you know too much damper could mean a dead fire but the flip side with forced draft is it takes longer for the fire to simmer down without damping and that means burned fuel. Since you can't be there for every cycle of the boiler I would use auto damping or none at all.

 

[j.w.young]

Thank you Cave2k for the tip on dampers. Since I'm using a large buffer tank, I plan to burn the wood boiler hot & let it go out when the buffer tank reaches target temp, I expect the aqustat to only put the boiler in idle mode if the fphx can't transfer the heat fast enough. My boiler is about 67000 btu & the fphx is rated for 150000 btu so that shouldn't happen til sometime near target temps. My home's heat demand was calculated by some pros at 57000 to 60000 btus. So I'm going to leave out any damper at this time, it will be easy to add one later if needed. I will put a stack surface temp gage on the exhaust pipe & watch it closely. I'm still putting the system together.