How Can a Stoker Overfire?

How Can a Stoker Overfire?

PostBy: Kubota2007 On: Thu Feb 27, 2014 8:25 am

Reading owners manual, warrenty void if Stoker is overfired, How can it happen and how do I protect it from happing? I could understand a handfired being overfired.
Kubota2007
 
Hot Air Coal Stoker Stove: Harman Magmun 20yrs old,Harmon Super Mag just installed.
Coal Size/Type: Rice
Other Heating: Electric,

Re: How Can a Stoker Overfire?

PostBy: oliver power On: Thu Feb 27, 2014 8:59 am

Good question??? However, I do know someone with a Harman Mag Stoker who says he has to run the stove hard in order to heat his place. He told me, every year he needs to replace his damaged grates.
oliver power
 
Stoker Coal Boiler: KEYSTOKER Kaa-2
Hand Fed Coal Stove: Hitzer 50-93 & 30-95, Vigilant (pre-Vigilant-II)
Baseburners & Antiques: MANY (Mostly when burning wood)
Stove/Furnace Make: HITZER / KEYSTOKER
Stove/Furnace Model: 50-93 & 30-95 , Kaa-2

Re: How Can a Stoker Overfire?

PostBy: Flyer5 On: Thu Feb 27, 2014 9:07 am

In this weather our 220 furnace in the shop runs flat out almost 24hrs a day. Not sure what defines over fire. We do not make anything that can be over fired. If it is over fired coal just falls off the grate. If the ash pan is empty it may ruin it.
Flyer5
 
Stoker Coal Boiler: Leisure Line WL110
Hot Air Coal Stoker Stove: Leisure Line Pioneer

Visit Lehigh Anthracite

Re: How Can a Stoker Overfire?

PostBy: Badog On: Thu Feb 27, 2014 9:24 am

The rheostat on my Alaska failed and when I discovered it hot coals were being pushed of the end. It was very hot but no damage. I was smart enough to disconnect the feed motor but leave the combustion blower on. Otherwise I suspect the fan would have melted and maybe without air the grate would over heat but the fire does not stay hot or last very long once the combustion air is off.
Badog
 
Stove/Furnace Make: Alaska
Stove/Furnace Model: Liberty

Re: How Can a Stoker Overfire?

PostBy: titleist1 On: Thu Feb 27, 2014 9:28 am

Basically it would be having the combustion fan blow too much air under the grates while feeding coal so fast that burning coal is going off the end of the grates. They have a pic in the old mag stoker manual indicating what overfiring looks like but there is no description saying how to avoid it.

Besides overfiring, too much combustion air could also pressurize the firebox causing CO to leak into the living space. That is why when setting up the restrictor plate on the combustion fan of the stove a manometer reading in the firebox as well as the flue pipe should be taken.

I am very surprised at the yearly grate replacement. Mine runs pretty much full time usually for about 2 months of the year (three months this year) and the grates aren't getting damaged. If he is cementing them in place maybe they are warping due to lack of movement.
titleist1
 
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: How Can a Stoker Overfire?

PostBy: oliver power On: Thu Feb 27, 2014 3:48 pm

titleist1 wrote:Basically it would be having the combustion fan blow too much air under the grates while feeding coal so fast that burning coal is going off the end of the grates. They have a pic in the old mag stoker manual indicating what overfiring looks like but there is no description saying how to avoid it.

Besides overfiring, too much combustion air could also pressurize the firebox causing CO to leak into the living space. That is why when setting up the restrictor plate on the combustion fan of the stove a manometer reading in the firebox as well as the flue pipe should be taken.

I am very surprised at the yearly grate replacement. Mine runs pretty much full time usually for about 2 months of the year (three months this year) and the grates aren't getting damaged. If he is cementing them in place maybe they are warping due to lack of movement.
Hi titleist1, Don't know what to tell you about grates warping , All I can tell you, is what he told me. We were talking about his Harman Mag Stoker. Which is how he heats his place. I liked the concept of the vertical feed.
oliver power
 
Stoker Coal Boiler: KEYSTOKER Kaa-2
Hand Fed Coal Stove: Hitzer 50-93 & 30-95, Vigilant (pre-Vigilant-II)
Baseburners & Antiques: MANY (Mostly when burning wood)
Stove/Furnace Make: HITZER / KEYSTOKER
Stove/Furnace Model: 50-93 & 30-95 , Kaa-2

Re: How Can a Stoker Overfire?

PostBy: Pacowy On: Thu Feb 27, 2014 4:35 pm

I think the manual defines overfiring to be any time when an external part of the stove or smoke pipe is glowing red. It can occur as a result of excess draft, and apparently as a result of running the unit with any of the doors open. I never heard of that latter one with the old Mags, but it's in the Super Mag manual.

Mike
Pacowy
 
Stoker Coal Boiler: H.B. Smith 350 Mills boiler/EFM 85R stoker
Coal Size/Type: Buckwheat/anthracite

Visit Lehigh Anthracite