Almost Had a Big Problem Last Night AA130

Got messed up on my days last week and had to relight Thursday afternoon. Got busy while it was getting going and made a mistake in not turning the feed motor back on. Friday I didn't get into the garage. This morning no hot coming to the indirect and I knew what I'd done. Just didn't think the old girl would go so far.

I figured I'd have about 250# of coal sitting on a cold ash bed and that alone would be a PITA to get going again. Nope, it burned up into the hopper, something I did not think could or would happen.

My garage is going to smell of burnt paint for quite a while. Should have seen me moving all that cooking coal out of there to get everything under control again. Now I know what Chernobyl must have looked like. Stupid ipod camera takes upside down pics I guess.

Nah, more like Centralia.

The pictures are upright when I click on it. Dennis

boy that coulda been a lot worse... you are fortunate it didnt ruin your hopper.

I have been reading about stokers I am actually rebuilding a keystoker right now to put in my house why does this happen and how can I prevent it? What if the power goes out am I going to have to shovel all the coal from the hopper so it don't burn my house down? Did this only happen because the combustion fan was running without the pusher on? I am totally new to the idea of stokers I have always used hand fired coal stoves. I am comfortable burning coal and I am very aware that it burns from the bottom up so I'm curious how do you keep the fire from burning up into the hopper during a power outage?

Your keystoker will not have this problem. The fire will simply go out without power.

Just to clarify, that AA130 is not a stock model, a stock one has no hopper. Instead they have a uphill hollow rotating auger tube dropping coal into a transfer tube which feed the fire.

Most units only would lose the fire, but even in that case a spring-wound timer switch wired to a N/C relay would upon running down the duration of the spring switch and automaticly switch the feed motor back on.

I had the problem of 250 lbs. of unburned coal sitting in the ash bin to address once.

I wonder if an AHS is subject to this same thing happening (fire getting up into the hopper) if the fan motor is mistakenly left switched off for an extended period? It has always been my understanding that if you ever needed to, you can shut them down by turning off the fan motor and simply letting them burn out (even with the hopper full), but now I'm not so sure of the safety of this procedure. To date I've only ever shut mine down by simply letting it run out of fuel. I.E., don't reload the hopper when it needs it, and after the last remaining coal in the hopper drops into the fire tube (during the normal operation of things) it will burn itself out in short order...

Or by your mention of "feed motor", do you actually mean what AHS would refer to as the ashing cycle motor (as opposed to the fan motor, with these being separate motors on the AHS)? AHS says to leave the ashing motor shut off for a couple hours after a re-start, and I've always wondered what might happen if I ever forgot to turn it on a few hours after the restart procedure. But now I think I know. There is no "feed motor" on an AHS, so that's why I'm confused here...

Either way, I'm glad to see that you and your family are OK! I can't imagine what might have happened if this took place in someones house.

Alvin wrote:I have been reading about stokers I am actually rebuilding a keystoker right now to put in my house why does this happen and how can I prevent it? What if the power goes out am I going to have to shovel all the coal from the hopper so it don't burn my house down? Did this only happen because the combustion fan was running without the pusher on? I am totally new to the idea of stokers I have always used hand fired coal stoves. I am comfortable burning coal and I am very aware that it burns from the bottom up so I'm curious how do you keep the fire from burning up into the hopper during a power outage?

During a power outage the fire would die out, never reaching the hopper. This was purely my fault. The combustion fan kept running due to a call for heat but the fire box could not get any new coal to burn. Had the ashing motor been repowered this wouldn't have happened.

I switched it off to build a bed of coals after losing the fire due to not filling the hopper the night before. Switching the ashing off keeps the spent coals on the bottom of the firebox to avoid warping the plate. Once a good bed is established and the combustion fan has stopped running (boiler up to temp) then I usually turn the ashing back on. That way the next time a call for heat comes in, the combustion fan AND the ashing motor run until the Anthrastat is satisfied. Alvin, this part won't make sense to you, it's an AA thing. Just putting it out there for AHS owners.

lsayre wrote: Or by your mention of "feed motor", do you actually mean what AHS would refer to as the ashing cycle motor (as opposed to the fan motor, with these being separate motors on the AHS)? AHS says to leave the ashing motor shut off for a couple hours after a re-start, and I've always wondered what might happen if I ever forgot to turn it on a few hours after the restart procedure. But now I think I know. Yes sir you do now, and me too! There is no "feed motor" on an AHS, so that's why I'm confused here...

Either way, I'm glad to see that you and your family are OK! I can't imagine what might have happened if this took place in someones house.

Yes Larry, I meant ashing motor. Feed motor=Ashing motor. On ours one cannot happen without the other. Symantics...

I'm glad nothing got hot enough to burn. There were a few things fairly close. One was a Tstat on the wall about 3' away. It was stuck over 80°F this morning and wouldn't release until I popped the cover off and gave it a nudge.

waldo lemieux wrote: boy that coulda been a lot worse... you are fortunate it didnt ruin your hopper.

Yeah, now we can do a really neat flame job this summer or something She did have a brilliant red area right at the neck for about 10 minutes this morning while I was digging the hot coals out and sending them onto the snow.

Can you mount a temperature sensor on the hopper so that if this happens in the future it would shut off the boiler? Seems possible, but it would have to be a manual reset circuit.
Would probably be a good idea because even if you had the ashing motor powered things can and will go wrong. If the ashing motor or controls were to fail I would think you'd have the same result.

Olllotj wrote:Your keystoker will not have this problem. The fire will simply go out without power.

Exactly. Same with an underfed stoker.

To many moving parts for my liking ....

But to each their own.

Wood'nCoal wrote:Can you mount a temperature sensor on the hopper so that if this happens in the future it would shut off the boiler? Seems possible, but it would have to be a manual reset circuit.
Would probably be a good idea because even if you had the ashing motor powered things can and will go wrong. If the ashing motor or controls were to fail I would think you'd have the same result.

I had completely forgotten that AHS Coal Guns have this feature. If a sensor positioned at the base of the hopper detects heat (above some threshold) in the bottom end of the hopper the fan will not run and the fire will go out. If you look closely at the avatar picture of my boiler, it is situated in the box that is positioned at the very bottom of the hopper, just above the hopper to boiler connection tube. You can also see the metal cable flex hose that runs between the hoppers gray 'heat sensor' box and the black box that houses the boilers main electronics.

Edit: You can see this much better in the picture of the boiler on the AHS webiste: http://www.alternateheatingsystems.com/coal-gun.html

Will be looking into that this week. Thanks for the idea guys.