How Can a Stoker Overfire?
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- Member
- Posts: 41
- Joined: Sun. Jan. 19, 2014 9:23 am
- Location: Ne Pa
- Hot Air Coal Stoker Stove: Harman Magmun 20yrs old,Harmon Super Mag just installed.
- Coal Size/Type: Rice
- Other Heating: Electric,
Reading owners manual, warranty void if Stoker is overfired, How can it happen and how do I protect it from happing? I could understand a handfired being overfired.
- oliver power
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- Joined: Sun. Apr. 16, 2006 9:28 am
- Location: Near Dansville, NY
- Stoker Coal Boiler: KEYSTOKER Kaa-2
- Hand Fed Coal Stove: Hitzer 50-93 & 30-95, Vigilant (pre-2310), D.S. 1600 Circulator, Hitzer 254
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.
- Flyer5
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- Location: Montrose PA
- Stoker Coal Boiler: Leisure Line WL110
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- Contact:
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.
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.
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.
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.
- oliver power
- Member
- Posts: 2970
- Joined: Sun. Apr. 16, 2006 9:28 am
- Location: Near Dansville, NY
- Stoker Coal Boiler: KEYSTOKER Kaa-2
- Hand Fed Coal Stove: Hitzer 50-93 & 30-95, Vigilant (pre-2310), D.S. 1600 Circulator, Hitzer 254
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.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.
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- Location: Dalton, MA
- Stoker Coal Boiler: H.B. Smith 350 Mills boiler/EFM 85R stoker
- Coal Size/Type: Buckwheat/anthracite
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
Mike