Stack switch for my stoker ?

I have an Anchor underfeed stoker, similar to the Will-Burt, under a oversized Kewanee boiler, Alaska, Healy subbituminous coal, 7500 BTU/lb. This combination works well, about half the ash that comes out is clinker and the rest is sort of like sand, I need to tend this combination about every 15 hours when we are at -20 F. My current problem is when I'm unavailabel to shut the stoker down and it runs out of coal or breaks a shear pin, I have yet to break a sheer pin, but I need to be ready. I somtimes go to town and don't always know when I will get back or for that matter leave, If I get an ambulance call at the end of my ten hour shift at work it can often be nine more hours before I get home, three hour ride one way to emergency room bla bla bla.

The stoker in the house my father grew up in had a stack temperature switch to detect fire out conditions, including didn't start conditions. I understand the fire had a specified amount of time to heat the switch or it would shut the stoker down, all reseting each time the thermistat shut the boiler down.

Older oil burners had these also, but set at a faster time since oil flames come up to temperature quickly, honywell builds a unit that replaces these on oil burners, current production units use an electric eye.

I don't seam to have any soot buildup anywhere in my stack, I do get some sandy ash in my horizontal fire tubes within the boiler, so I think a sensor in the stack would be acurate for these purposes.

My boiler has a port just before the stovepipe for this switch.

So the question is where can I get one of these old fashioned stack switches?

Maybe I need to buy a Honywell stack switch and figure out how to add time to the system.

Any type of SNAP switch or Temperature switch should work. DO a Search on SNAP SWITCH, you can get them in various temperature settings or variable. Maybe 60-100 degrees or less if it flames out, stops the stoker (or kills power to everything, however you want to wire it). We have discussed it for our stoves too.

Grainger, Thermodisc, etc....check ebay.

I understand wiring the stoker through a snap switch on the stack, how do you get the delay, meaning I don't think my stack gets hot from the fire for about five minutes, and I need to power the stoker while it is heating up.

I know nothing about wiring, but i would think you could wire a switch that will give you a override position for starting the stoker.

Yes, just wire a toggle (wall) switch in parallel with it for an override, just turn the switch on until you get a established fire and then the snap switch should kick ON, then turn the manual switch off. If the temp falls below the temp switch setpoint, it will stop the stoker or stove, depending on how you wire it.

I understand the most basic of wiring but, when my stoker is off for four hours the stack is cold, I'm at work, and the stack switch without a time delay would not allow the stoker to start. It takes about ten minutes more or less for my stack to warm up on every start.

I would focus on finding ways to extend the time that one hopper filling lasts. Do you know how much the hopper holds? I'm guessing at least 200 pounds, so that means you're going through maybe a quarter ton in a 24 hour period...? That could be too much depending on what you're heating and how the system is setup. If you explain your system in detail there are members on this forum that are really good at diagnosing issues with hot water heat and might have some ideas to save coal. Are you using a barometric damper? It would help keep more heat in the boiler. Could you make the hopper larger? That could be difficult if the hopper is sealed(hopper lid has gasket). Is there any higher btu coal in your area? Too bad there's no one that could come fill your hopper when you're not around

I have a no frills system.

Pile of coal on floor of unheated garage without any doors, just a shell, -6F and windy today, garage is not getting finished till summer.

Coal is shoveled into Anchor stoker hopper and door is closed on bin.

Thermistat in house calles for heat, circulation pump comes on, when boiler gets below 160 F stoker comes on, if for some reason boiler is below 140 F when thermistat calls for heat circulation pump waits for stoker to get boiler up to 140 F then starts.

Boiler has about 70 gallons of fluid in it and is a two pas horizontal tube Kewanee boiler, stack is 9" choked to 8", my mistake but I'm not using it anywhere near capacity, no barometric damper

Anchor stoker is very similar to the Will-Burt underfeed, forming some clinkers and some ash, no smoke, or smell, clinker ring probably needs to come out every 12 to 15 hours.

Coal is from Healy Alaska, Usibelli coal mine, 7500 BTU/lb, 25% water, 2500 F fusion temp on ash as I understand from web site.

Last sugestion was to enlage hopper, I would still need to clear the clinkers from the grate because if you don't they will hold the heat on the grate and melt them, I've been told, really would like a rotating ring stoker, similar to EFM's unit, seen videos but no more.

I could put some sort of mechanical switches on a external shaft on my gear box to detect a broken sheer pin but want to try a old fashioned, or modernized stack switch.

How well is the boiler insulated? I would insulate the boiler since it is totally exposed to Alaska winter temps. It looks like some of the pipes aren't insulated either..? Anything you can do to stop heat loss will help with coal usage. How big is the mass of clinkers you're getting?

Yes I have some efficiancy problems, (other than spelling efficiancy).

Pipes now have some insulation on them, boiler skin temp is about 40 F, based on infrared thermometer.

Clinkers are about toster size in volume and cresent moon shaped.

I can list some obvoius problems if you would like.

I seam to have a coal addiction, and no woman, these issues could be related.

Dwelling is 12' by 16', whole shack is a 12' by 32' wharehouse from the railroad circa 1945, 4 by 4 studs every four feet, four layers of shiplap with tar paper for insulation, I've added some foam board under the sheet rock.

Picture window is two single pane windows stoped into the framing, you remember the wavy glass that makes things move and wiggle as you move your head, not to mention one of the outside panes is broken.

When you hear a gust of wind outside you feel coolness on your face.

I have 6' of baseboard in the crawlspace to keep the plumbing working.

I have a zone that sends hot water out to 300' of pex around my septic tank, under the four inches of urathane foam, same zone sends water to 300' of pex that is on each leg of my drain field, under 6" fo styrafoam and two feet of dirt, these zones have not been needed this winter yet, last winter they were heated from a heat exchanger from a side arm hot water tank on my coal cook stove, I sure like not lighting that stove this winter.

I have about 30' of baseboard inside this shack and it just stays warm

My goal is to just feed the coal to it and get to spring. First winter here didn't have any water, and this shed was on blocks with just 3" of wood between my bed and the outside, sheets would freeze down to the floor with the frost from my breath, now it's on a foundation, and I have a toilet, and cental heat, I'm moving up.

Attched are some pictures of the side arm from the cooking range and the heat exchanger to allow for glycol in the field and septic circuts, installed last winter, to get the toilet working.

the Epsom salts attract the elk???

Epsom salt for toe that was disintagrated by "V"-plow for five yard wheeloader, but that's another story.

If you like to crunch numbers check out the frozengore.com carbon footprint of 460 Ford vs. Lear Jet from Tenassee to Europe, but I should stay on topic

Short Bus wrote:First winter here didn't have any water, and this shed was on blocks with just 3" of wood between my bed and the outside, sheets would freeze down to the floor with the frost from my breath, now it's on a foundation, and I have a toilet, and cental heat, I'm moving up.

Now that's roughin it!
With that climate and the coal you're using you'll probably need to tend the furnace/remove clinkers at least twice per day.
That stoker will last a long time if properly maintained and your whole setup will work better if you get the garage enclosed. For now I would insulate everything the best you can....depending on your location in AK, you could have another 4 months of winter.

Nice place

to defeat the normally open snap switch during start up - over wire a bathroom fan shutoff timer in series with it
- when starting -- just crank 20 minutes on the timer and your stoker feed will operate at least that long - by then, the snap switch should be satisfied and you will be in normal operation.

I wouldn't be too worried about loosing fire if a shear pin fails -- if it does, the feed system stops anyway.

My kind of place.. I love it. Ya do what ya got to do..

Suggestions.. Is there anyway you can put tarps over the garage doorways?? or will they just get blown away in storms?? Anything to enclose the building and stop the frigid air circulation.
As mentioned, anything you do to insulate, enclose, conserve will conserve on the coal use.

Very interesting to read about burried pex around the septic and drain field. I always wondered how a septic system would work in the permafrost.
When I was in AK many years ago, I saw many homes that were abandoned, all tilted or sunk in the ground because they had melted the permafrost and basicly sunk in the mud.. What is the current method to build a foundation that won't melt the permafrost and leave you with a level and 'safe' house ?? Stilts? or just build a foundation and make sure it stays cold and doesn't melt the frost??

Anyway, have you experimented with letting the stoker run a long time, just to see what happens when the clinker builds up? I think you will loose efficiency, but I don't think any perminant harm will occur.

I think Sting's timer and WNY's snap disc temp sensor combination will do the job for you. How well does the chimney draft? what happens when '[ if ] you get a power failure? Will the fire keep with no combustion blowers or coal feed for several hours? My Iron Fireman underfeed [predessor to Wilburt] stoker will hold an anthracite fire for more than a day.

Very interesting setup, My hat is off to you for making it work.. And for your job. Driving in AK is a challenge at times..

Greg L