24/7 Combustion Fan Draft?

24/7 combustion fan draft?

PostBy: coalkirk On: Sun Dec 18, 2011 7:44 am

So those of you who have modified your stokers to have the combustion fan run 24/7 where do you run your draft? Harman says .04-.06 for the VF3000 boiler. I have been running it at about .04 but recently adjusted it to .02. Seems to do fine. Stack is alittle cooler and I assume there is some fuel savings. The baro is pretty wide open at this setting.
If I'm not mistaken, Keystoker boiler combustion fans run 24/7 from the factory and I think they recommend .02.
Stoker Coal Boiler: 1981 EFM DF520
Coal Size/Type: anthracite/rice coal

Re: 24/7 combustion fan draft?

PostBy: WNY On: Sun Dec 18, 2011 8:12 am

Both my stoves run the combustion blower 24/7, I keep the drafts at .04 at full burn, they do get down the .02 sometimes on idle and warm outside. Boilers might be a bit different, so you don't overheat them, by modulating the fans.?
Hot Air Coal Stoker Stove: Keystoker 90K, Leisure Line Hyfire I
Coal Size/Type: Rice
Stove/Furnace Make: Keystoker, LL & CoalTrol
Stove/Furnace Model: 90K, Hyfire I, VF3000 Soon

Re: 24/7 combustion fan draft?

PostBy: Rob R. On: Sun Dec 18, 2011 8:33 am

Keystoker's draft recommendation for the boilers is -0.02" of WC over the fire, not at the flue collar like many others. EFM says -0.01 to -0.02 overfire, and -0.04 to -0.05" at the flue collar. I run mine at -0.02", as measured through the firedoor...I have never checked it at the flue collar.
Rob R.
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Coal Size/Type: Lehigh Rice
Other Heating: Dad's 1953 EFM Highboy

Re: 24/7 combustion fan draft?

PostBy: qbwebb On: Sun Dec 18, 2011 8:46 am

I have my baro set at .02 and take my reading right at the exhaust outlet, when it gets warm and muggy out I will have to turn up the 24/7 blower setting or I will get an out fire. My exhaust temp when I last checked in early nov was around 240 if I remember right. I am trying to run the unit cooler as well this yr, 150F instead of 180 like last year. The way I figure it you extract more heat from the exhaust the cooler the water is, its not a linear relationship, the down side to this is I think I'm getting a little less BTU's out than before, but my coal is burned nicely (last year I ran with 1/2" or so of ash at the end of the grate, now I have maybe 1.5"). I've been supplementing with wood inside recently and its been helping with the boiler load quite a bit, 16F here this morning.
Stove/Furnace Make: Harman
Stove/Furnace Model: VF3000

Re: 24/7 combustion fan draft?

PostBy: titleist1 On: Mon Dec 19, 2011 12:26 pm

The reading on the manometer is .02 - .03 in pilot mode and .04 - .05 when at full temp of about 550 - 600 on the side of the stove.
Hot Air Coal Stoker Stove: Harman Mag Stoker (old style) one in basement, one in workshop
Hand Fed Coal Stove: Harman Mark III on standby for long power outages
Coal Size/Type: Rice/Anthracite; Nut/Anthracite

Re: 24/7 combustion fan draft?

PostBy: MURDOC1 On: Mon Dec 19, 2011 12:33 pm

With my Coal-trol powered Magnum I set the baro for .04 at full burn and it will dip down to .02 at idle fire or warm outside temp...
Stove/Furnace Make: Alaska/Franco Belge/Harman
Stove/Furnace Model: S.S. 2/ 144.08.02/ Mag Stoker

Re: 24/7 combustion fan draft?

PostBy: BrotherDave On: Mon Dec 19, 2011 7:06 pm

I run my fan fully open. My draft averages at least. 03 at the damper, even at idle. Never tested the the over fire yet. In the summer I cover the damper and got at least 02 at the damper at idle.
Stoker Coal Boiler: Harman VF3000
Hand Fed Coal Stove: Godin 3727 / King KCC205
Stove/Furnace Make: King/Godin/Harman
Stove/Furnace Model: KCC205/3727/VF3000