Install a Barometric Damper on a Stoker Stove/Furnace?

coalishot wrote: I don't think over drafting a stoker is a real concern for coal use as u only feed so much coal at a time.

But a hopper fire from over drafting is.

You would have to be drafting extremely high to even begin to worry about that. remember we are talking in fractions of an inch water column. a draft difference between .04 and .09 is not an issue. Also since my draft is up my flu pipe temp has dropped. my hopper is cooler and all condensate in hopper and on lid (which even started to rust) is gone. I am going to call Alaska again to see what they would consider dangerously excessive draft in this model stove. Might as well be safe than sorry. I must say I am extremely pleased with current stove operation at last. Still will calculate electricity use of inducer however as 3 motors running 24/7 all winter can add up.

Also it appears to me that with the higher draft the opposite is occurring the flames are being pulled up and away from the hopper making a fire even more unlikely. I think I was more at risk for one before.

coalishot wrote:Also it appears to me that with the higher draft the opposite is occurring the flames are being pulled up and away from the hopper making a fire even more unlikely. I think I was more at risk for one before.

A hopper fire occurs because the draft is pulling hard and is pulling air through the coal that is in the hopper. The fire will follow the air flow. So if you have a lot of air being pulled through the hopper the coal will be ignited all the way from the grate into the hopper. I can't speak for Alaska but Jerry the owner of Leisure Line doesn't want anymore than -.05 draft on his stoves because of risk of a hopper fire. I would Definitely call Alaska and find out the max draft they recommend. Also with a higher draft you are pulling the heat out of the stove before it can be transfered through the stove and into the house.

The draft doesnt pull through the hopper on my model. The hopper is sealed. The least path of resistance is through the grate which is being induced already by the 2.nd of my 3 motors (still not happy about running 3 motors). The draft pulls from the top of my stove where the flu connects which is away from the hopper. The added draft since I got inducer is pulling flames up and away from hopper. If the fire follows the air flow it will be away from hopper as I am pulling air away from hopper and not pulling through hopper. Your stove may be different. if I removed hopper lid the draft would still not be pushing/pulling into hopper.It would still be pulling through stove and grate and yes that 2nd motor *i hate all these motors) and up and out very top of stove. I cant imagine any difference in stove operation between .04 and .05 or even .08. I realize more heat is doing up flu but I can live with that knowing that when I turn unit down hopper wont condensate and co wont enter house on med low .02 was allowing fumes in house. Probably Why Alaska requires .04 minimum is for low fire settings. Will check with them but I think the difference between .04 and .09 is negligible. But then again I ve been wrong before. It took me 3 weeks just to get this thing to run correctly.

Why do I remember 40 years ago my Grandfather putting a shovel in the morning and a shovel in at night no co detectors no manometers no baro no motors. grates in floor and no problems. And the whole neighborhood was the same. Seems coal burning got harder not easier.

coalishot wrote:The draft doesnt pull through the hopper on my model. The hopper is sealed. The least path of resistance is through the grate which is being induced already by the 2.nd of my 3 motors (still not happy about running 3 motors).

I realize it is a stoker stove, when your chimney is drafting a lot more than your combustion blower can supply where does the extra draft come from? (the hopper)

coalishot wrote:The hopper is sealed.

I thought that the Harman DCV was the only sealed stoker stove but I could be wrong.

coalishot wrote: if I removed hopper lid the draft would still not be pushing/pulling into hopper

Oh yes it can. Even more so with a hopper that is low on coal.

I am not trying to be a wise guy here. All that I am trying to do is keep you safe. Just call Alaska to be sure. -.09 draft sounds very high to me for a stoker stove.

I understand what you are saying but my hopper has a lid. Assume it did pull through hopper it would be pulling flames away from coal as it is now. now If it pulled the hopper into negative pressure which it could with the lid on then the flames could burn back into hopper. I will ask Alaska they only give you a min. of .04 not a max. It ran perfect all night on #2 which is a very low setting. Will be tweaking it down to about .06 to prevent excessive heat loss in chimney. But will still call Alaska just to see what they say is to much draft.

Dont think your being a wise guy just have 30 years experience as HVAC tech at journeyman level and understand how low .04 is.And how little a difference .04 to .09 is. But I am new to coal and appreciate all input

Pics to follow as soon as I get motivated today in the rain.
Also will do math on inducer blower to see what energy use is.

Did math on inducer motor. it is rated at .43 amps at .09 cents per kilowatt hour (for now in Pa see this link
**Broken Link(s) Removed** ) running 24/7 for 31 days a month I come up with $3.45 a month to run it. The combustion fan on my liberty is much smaller but I don't see amp or watt rating but it must be about half the draw of this motor. The blower motor is in housing and I cant see that tag either but I would say it is probably twice the use of the inducer I will put amp probe on both and get actual readings and post some day soon. Also rated watts and amps are usually max and most motors run under rated amps/watts.

Coalishot, please understand that we have dozens if not hundreds of people on the forum that have each years of coal burning experience,, AND we have manufacturers like Jerry of LeisureLine stoves who has sold thousands of stoves in his career..

With all the above knowledge and combined experience condensed into the few who study and post often on this forum,, PLEASE don't discount our advice..

Too much draft has been PROVEN to cause hopper fires.. coal burns TOWARDS the air source.. too much draft will draw air through the coal in the hopper and through the stoker mechanism.. the lid is NOT sealed and even if it was, the stoker mechanism is not airtight.

It's a simple thing to use a barometric damper properly set to what your Stove Manufacterer says is the correct draft.. Too little causes the problems you have had, too much causes other equally dangerous problems.. A barometric damper only limits the maximum draft.

Safety first..

Greg L

coalishot wrote: Seems coal burning got harder not easier.

I don't want to offend but this comment doesn't make sense to me.

Hi Coalishot,

Just a few points here:
The hopper on your stove is not sealed because it has a lid on it. The lid IMO is more cosmetic then functional. One point I think needs clarifying is that just because the draft is pulling the fire away from the hopper it has no bearing on the chance of a hopper fire. With coal the fire travels towards the oxygen source. This means that if the draft is too high on a stoker stove it will exceed the amount of air being supplied by the combustion fan. At this point it's the "path of least resistance". Combustion air will enter the stove anywhere it can, through the easiest place. If it is easier for the air to enter through the hopper then past the running combustion fan-that's where it will occur. Since that happens to be where fresh coal is then the fire will burn towards the fresh air.

Too low a draft-combustion finds it's way out anywhere. Too high a draft-fire burns back towards the hopper. It's as simple as that. A properly drafting stoker stove doesn't need a lid on the hopper. I don't have one on mine, as a matter of fact I don't even have a lid for it. You repaired the low draft problem, now I would set the draft to -04" where it is supposed to be and enjoy the heat.

Finally, your grandfather was probably feeding a convection furnace, a hand fed unit is much less finicky and is less problematic when not operating correctly.

Right now you are in the learning curve, I went through it like everyone else. Coal is a totally different animal than what most people are used to.

ok talked to Alaska. They know entire history of my problems. Told them with inducer I am fine but if I set draft at .04 I have excessive moisture in hopper and condensate on lid. Told them I need a min of .06 to have dry hopper and bin. they instructed me to run at .06 an I will have no problems with hopper fire. Obvious more heat is going up flu but to have co readings of 0 at all times and no sulfur smell when on low setting. I'll take it.
Overall satisfied with stove . Didn't like spending extra money on s.s. liner in brand new chimney and of course having to install the ugly inducer motor (as stove sits in my finished basement) and the extra noise and electric to run motor. But the math shows about a 1.5 season payback and that doesn't include the extra warmth factor in house so It was worth it overall.

coalishot wrote:Did math on inducer motor. it is rated at .43 amps at .09 cents per kilowatt hour (for now in Pa see this link
**Broken Link(s) Removed** ) running 24/7 for 31 days a month I come up with $3.45 a month to run it. The combustion fan on my liberty is much smaller but I don't see amp or watt rating but it must be about half the draw of this motor. The blower motor is in housing and I cant see that tag either but I would say it is probably twice the use of the inducer I will put amp probe on both and get actual readings and post some day soon. Also rated watts and amps are usually max and most motors run under rated amps/watts.

.09 cents per kilowatt hour? Thats half of what I pay in my neck of the woods.

Here is a question on to much draft.

My EFM is an 8" pipe. Two Tee's to get to the thimble. I have a reducer to a 7" baro at the end of one Tee. I see lot of stoves here just like it minus the reducer for the baro. I get .03 to .04 over the fire and .05 on the output side. My inspection hole is higher than EFM recommends. Its about 18" from stove vs. 12". If If the stove is running or idle the baro is open a good bit. If I force it close my draft goes up to about 1.0

Think I should get an 8" baro or the 9"

I called Field Controls today and talked to their tech support.
He told me an 8" would work but because my chimney is 45' high with an 8x8 flue he recommended a 9".
He also told me putting the baro on the end of the T wasn't right and I needed to move it.

John, the biggest difference is going to be with a hot burn, a cold day, and a wind ... I think. Why don't you try blocking a part of the damper opening, also try opening the damper all of the way, while taking your draft readings with a hot burn. See if there is much of any difference. You might get a clue of what to expect from a larger baro.