Stokermatic coal stove - switch issues, need some help

Hello all -

We're out in western Colorado, and are trying to help an older neighbor bring her stove back around. It's been acting up a lot lately, and have run into a bump in the road. I need some direction from the pros!

She had an experienced coal guy come over to make the repair on the switch, but instead the exact opposite happened. He inadvertently broke the switch, then unwired everything and left it all wide open. He got frustrated and left, leaving all the wires just dangling....and it's a mess for me to decipher.

Here's the switch we replaced (it's a double pull, double throw - if I'm using that terminology correctly):



SO - we wired the hot lead to the middle terminal. On one of the other ends we wired JUST the circulation fan, and on the other end we wired the auger/combustion fan. So far, it all seems to be working well.

Here's our real question - there is one more wire that runs up to this stuff here (and I have NO IDEA what all of this is! I need some direction!):



What is all of this? I had anticipated that it might be a temperature-controlled switch, that once a certain temp was reached, the circulation fan would kick on and blow hot air into the room. Also - it would keep the fan circulating until a certain safe "cool" temp was reached. All of these assumptions are based on my own experience with my own pellet stove. Definitely not the same as the coal stove - but gotta be relatively similar.

What is the second big black block in there? What's the big "coil" looking thing under the left side of the switches?

Here's part three (this is below the actual double pull double throw switch):



I can't tell what it is, nor what it does. No matter what I push/pull, nothing seems to come off, go off, etc....anyone know what this thing is? Does it matter to the operation of the stove?

Her stove is supposedly thermostatically controlled by the wall thermostat. The way she describes it all goes like this: she builds a wood fire in the fire box, and flips on the auger. Once the wood fire reaches temp, the coal begins to burn, and as long as the wall switch is calling for heat, the auger pushes in coal. Once the room reaches temp, the auger/combustion fan stops working/pushing coal. BUT - according to her (the owner), the circulation fan is SUPPOSED to continue blowing...but right now it's not working that way. In fact, we couldn't get the circulation fan to come on by itself at ALL. Ever. We can make the fan come on by flipping the double pull/double throw switch to the other side - and that hard-wires the fan to come on. Because of that, we know the fan works. What we can't discern is how does the fan come on by itself - is that what the dark black boxes are for? That's what I had assumed....but I really have no idea.

I know that's a TON of questions - but figured I would just jump in with both feet. I'm stumped by it all, and could really use some direction.

Any help will be GREATLY appreciated! I can't seem to find a wiring diagram anywhere - not for the switch, not for the fan - nothing. We're just shooting in the dark....so if you could steer us that would be awesome.

Thank you so much -

Picture one is a double pole double throw switch.

I think you are going to need to conect this so you get power to combustion motors and power to the air circulation system at the same time, probably not one or the other as you described.

Picture two looks like adjustable temperature sensing switches.

One switch probalby controles the air circlation fan, starting when heat exchanger is warm and stopping before it blows cold air around the house.
One switch probalby controls the burner, shutting it down on overheat.

Picture three a timer actuated switch.

This is probalby for keeping the fire burning when there is no call for heat, stokers often run for a few minutes every hour or so to keep the fire burning, pellet stoves can start thier own fire but coal stokers use a keep alive timer system. Keep in mind this timer could start the stoker at any time even after it just fired and satisfied the call for heat at the thermistat.

Better and more acurate information will follow, you sound like you have some understanding of this.
Look on the backs of panels and around the stoker for envalopes that contain wiring diagrams and other information.

Short Bus wrote:Picture one is a double pole double throw switch.

I think you are going to need to conect this so you get power to combustion motors and power to the air circulation system at the same time, probably not one or the other as you described.

Picture two looks like adjustable temperature sensing switches.

One switch probalby controles the air circlation fan, starting when heat exchanger is warm and stopping before it blows cold air around the house.
One switch probalby controls the burner, shutting it down on overheat.

Picture three a timer actuated switch.

This is probalby for keeping the fire burning when there is no call for heat, stokers often run for a few minutes every hour or so to keep the fire burning, pellet stoves can start thier own fire but coal stokers use a keep alive timer system. Keep in mind this timer could start the stoker at any time even after it just fired and satisfied the call for heat at the thermistat.

Better and more acurate information will follow, you sound like you have some understanding of this.
Look on the backs of panels and around the stoker for envalopes that contain wiring diagrams and other information.

First off - THANK YOU~ it's good to know that someone out there can help me fix up this mess. We'd love to get her back on track with this whole thing. She doesn't have the means to throw $1500 at a replacement stove, so if we can help get her back on track for just a little sweat equity, we're all for it.

Double POLE switch. Pardon my bad terminology. I'm still learning about all this. I appreciate you saying that - makes much more sense than double pull - what would that even be? Double POLE aligns perfectly with what we found on the switch.

OK - about the switch - let me back up a bit. When I first got involved in this, the original switch worked like this: flipped to one end was JUST circulating fan, nothing else. Not sure how long it would have run when activated, but I'm guessing it would have stayed on forever. When the switch was in the middle - nothing (full off). When the switch was flipped to the OTHER side, the auger came on AND the combustion fan came on....but I never saw the circulation fan come on, ever. That might be because it had been monkeyed with at some point, or because some sort of temp-activated switch had given out, or because it NEVER came on and the owner just remembers it inaccurately. Might be some other reason that I can't think of - but the fan never came on. Makes sense that it WOULD come on at some point, maybe right away (with the auger and combustion fan) or maybe when the firebox reached some magical temperature (that's my guess).

When we installed the new switch, we wired up hot to the middle, the auger/combustion fan to one end, and the KNOWN fan wire to the other end. There was/is a fourth wire that runs to the "adjustable temp switches" - and from there......I really don't know what happens. In truth, I should say it CAME from the adjustable temp switches, right down to the double pole/double throw switch. I didn't know where to wire it up, but my pseudo-logical thought was that if I joined it up with the auger/combustion fan pole, it would have available power the instant the auger/comb fan was activated....and once the adj temp switches reached temp, it would come alive. I've not been able to make that happen, however.

Here's what I'm wondering: Perhaps I should have wired it up with the known fan hard wire on the same pole as the auger/comb fan. That way, the fan would come alive the instant the auger/comb fan were activated. Then, the unknown adj temp switch wire would come down and attach to the OTHER end of the switch, all by itself. Not sure if that's right or not, but we didn't try it that way. It seems like it would eventually blow cold air, though - right? If the fan comes alive immediately when the auger/comb fan come on, then it would blow cold air until the firebox was up to temp, and would continue to blow even after the firebox had cooled - correct? That's not a good solution either.

Does that make sense? A long explanation for a simple question, but I want to be as descriptive as possible.

I have a gut feeling that one/both of the adjustable temp switches have gone bad. That's my gut instinct. The fan would be coming on if they were functional, but something isn't allowing the circuit to close, telling the fan that it's time to get blowing. That's my hunch, but I have no idea. Anyone know?

Keep it coming! We'll get this thing nailed down one way or another! haha! Who doesn't love a good challenge.....bring it on.

Thank you again - I really appreciate your help.

Welcome!

The first photo is double pole double throw as was mentioned. Flip it one way (heat) powers the stoker control and hold fire timer. Middle position is off. Flip it other way should only run the circulating fan.

Second photo appears to be the fan limit switch....if it's on the back of the unit between the circulating fan and the toggle switch.

Third photo is the hold fire timer and thermostat relay switch.

rockwood wrote:Welcome!

The first photo is double pole double throw as was mentioned. Flip it one way (heat) powers the stoker control and hold fire timer. Middle position is off. Flip it other way should only run the circulating fan.

Second photo appears to be the fan limit switch....if it's on the back of the unit between the circulating fan and the toggle switch.

Third photo is the hold fire timer and thermostat relay switch.

The owner never mentioned a Hold Fire timer, but she obviously has one. Think that is what the unidentified fourth wire might be? Coming down from the adj temp switch/fan limit switch?

I'll bet she doesn't realize that her unit has a hold fire feature. She may - but she's never mentioned/described it any way. Doesn't really matter. As long as I can get it working/keep it working that would be awesome.

Now....about that UFW (unidentified fourth wire!).......

prob not to run the hold fire timer, huh?

How about this: what's the correct way to wire this new Double Pole/Double Throw switch? Only one half (lengthwise) is powered, correct? Whatever side you attach the hot wire to, that's the side. So you have only one hot/live terminal on each end, correct? The fourth wire HAS to share a terminal with something else, correct? Otherwise, it's connecting to a blank, unpowered terminal - correct? That's what I could discern with my voltmeter and testing for continuity.

Wahoo! Getting closer!

cptmoney wrote: When I first got involved in this, the original switch worked like this: flipped to one end was JUST circulating fan, nothing else.

This is operating correctly.

cptmoney wrote:When the switch was in the middle - nothing (full off).

Right, this if "full off" position.

cptmoney wrote:When the switch was flipped to the OTHER side, the auger came on AND the combustion fan came on

This is correct operation if the wall thermostat is turned up enough to call for heat.

cptmoney wrote:but I never saw the circulation fan come on, ever.

How long did the stove run? The stove should have gotten very hot without the circulating fan going....did it get hot?

I suspect the fan limit switch may be bad....if the circulating fan not turning on is the reason the repair person was called then I think that's still the problem.

cptmoney wrote:It's been acting up a lot lately

How exactly has it been acting up? (I mean before the repair guy looked at it)

rockwood wrote:How exactly has it been acting up? (I mean before the repair guy looked at it)

Ooh - Rockwood- great question. I never mentioned that in my original post.

The reason I got involved is that the stove began just "dying" right in the middle of a burn. She would wake up and the house would be cold and the firebox would still have coal (mostly half-burned) in the firebox.

When I came over, I discovered this:



The terminal that held the power for the auger/comb fan was loose, and the stove would lose connection and just die. A friend and I bent the wires just enough to make decent contact with the understanding that she'd call her "experienced coal stove guy" and he would get the correct parts on order and get her back on track. Well, he came over and officially broke the terminal right off, got frustrated, and pulled out. I don't think he's a repairman at all, just a gentleman whom she knows with some coal stove experience. When he left, all the wiring was just dangling loose and the switch was sitting at the base of the stove.

We ran down to Radio Shack and found a very similar switch (although not an EXACT replacement) and whipped to her place to install it. the original switch was a 15 amp, but all we could find was a 10 amp. Being in the middle of the coldest week of our winter, we figured we had nothing to lose, so we went with it (the Radio Shack validated us in this move, so we figured we would be safe!).

All that loose wiring is what got us in the mess. Had we been there to move one wire from the old switch at a time, then I'd feel certain that we had at least wired it up correctly, and then I'd know that the fan limit switch was likely bad. As it stand now, however, I don't know if we've wired it up correctly or not - which makes re reluctant to point the finger at any additional components. The more you guys help me out, however, makes me believe that it is, in fact, toast.

You think we're on the right track, then? Does anyone know how to test the fan limit switch? Know where I can find a replacement? This stove says Stokermatic Super Heater on the front panel. Outside of that, I have no idea which model we're even working with. Just kind of fumbling our way through in the dark.

Part 3 should have it's wiring diagram on the inside of the cover piece.

See if this is of any help.

McGiever wrote:Part 3 should have it's wiring diagram on the inside of the cover piece.

See if this is of any help.

77B Wiring Diagram (Pg. 9).pdf

Nope - nothing. Nor anywhere else on any of the panels as far as I can see.

Thanks for that diagram, McGiever - I'll see if we can pull some details from it to get us down the road...

Sorry I had to leave for a while...The fan limit switch might be ok. The faulty connection on the switch could have been the only problem here.

I have the same furnace but with a later model fan limit switch.

Are you getting any line voltage (approx 120 volts) to the terminals on the limit switch (second photo) when the toggle switch is set to "heat"?

There should always be voltage to it in heat mode for the fan to be able to kick on when the heat exchanger reaches the set temperature to keep it from overheating.

Where is this extra wire? Does it have smooth insulation on it or rough?

Is the wiring at the toggle switch the only wiring that was messed with that you know of?

The double pole, double throw switch would work nicely to run the circulator fan in somthing called the summer position.

Basically power to the center of the switch on one side, throw switch one direction and fan starts with nothing else, summer cooling or at least circulating. Throw it the other direction and the furnace should come to life.

I'll bet those temperature sensing switches are ok since you have an obvious failure on the old switch.

For me power is going to need to come from the main switch to an over temperature switch and then go to the stoker and the timer, this same power should need to go to the other temperature switch to run the circualtor when the correct temperature is reached. Realize that the thermostat is involved somehow.

I'm not sure why they need a double pole switch, and they may not have, but that was what was available.

Place a jumper wire between the two center terminals on the double pole switch. Move the fan wire over to the new side that was powered, keeping it on the end you were using. The fourth "mystery wire" put on the terminal that is on the other side of the switch from the auger and combustion fan but the same end. The double pole switch will power the fan in the one direction. When the switch is placed in the other direction, it will power the auger and combustion wires, on one side and the wire that runs to the "limits" on the other side. When the T-stat calls, it energizes the limit (relay) on the left. The wires for the auger and comb. fan pass thru this limit (relay). The limit on the right turns the air fan on when the temp rises above set point and will continue to run until it goes below set point. Can you see where the temp on the right limit is set at 160 degrees or so. The rest should be wired correctly.

Morning everyone -

I had to disappear for a bit last night, but I think we're super close on this thing.

According to the stove owner, two guys were up there to work on the stove (prior to her getting me involved). The first guy cleaned/emptied/oiled/refilled everything, but never found the bad switch (and also never messed with any other wiring), so he moved on. The second guy came to address the switch, but got frustrated and bailed - but supposed never messed with any of the other wiring. She thinks all the rest of the stove's wiring is just as it has been for years.

There a lot of questions I need to catch up....first of all, the mystery wire leads from the double pole/double throw switch area to the therm-controlled switches. The wire wasn't rough, necessarily, but it's all older, cloth covered wiring. Those are found at the back of the unit, near the top. There's an access panel approx 4 X 6 inches or so. It was tough to determine exactly where it went, as it runs behind the back panel of the unit, and is clustered with several other wires. From using a continuity test, we BELIEVE that it was/is this wire here:



Interestingly enough, the wire just to the left of the hightlighted wire also tested continuous with the highlighted wire, like the switch was already closed (even though the stove was off at the time). Not sure if that's correct or not - just pointing that out. I may need to recheck my details on this, but I think that's what I recall.

Now - the two temp switches/limit switches: they do have adjustable dials on them. If my memory serves me (again - I'll have to check to confirm) the one on the right (as we're looking at them in the photo) was set a bit lower, around 150 degrees - I THINK. The one on the left was a bit higher, set at 170. I may have that backwards. I can check pretty easily, and will do so later this afternoon. I'm not sure what amount of voltage the switches are/were getting when the main switch is set to "heat". I can check. Honestly, I wasn't sure where one limit switch began and ended. Am I correct in that there are 2 switches there, and the wire comes in at then out at the center, with the two terminals on the same switch divided by that small plastic wall? If that's the case, then the switch on the left was already in closed position, even with the stove not being hot, as it tested continuous right away.

I like your idea to jumper the switch, Scottscoaled. That makes good sense, and will give each wire its own terminal. The way you described to wire it all is just what we'd suspected it should be. In fact, we've wired it all just like that, save for the fact that our auger/comb fan AND circulation fan wires are sharing a terminal (simply because I hadn't thought to jumper that center power terminal). Thank you for the detailed description!

At this point, I think we've got it wired exactly right. It was obviously a broken main switch that set this whole process in motion, and I think we're in good shape on that front (I'll get it jumpered today). I just want to check that her fan limit switch is working and doing its job, since I've never seen the fan come on at all when the main switch is set to "heat". Either we never got it hot enough to call for the fan, or the limit switch is bad (or perhaps just improperly adjusted). Is there an easy way to test the limit switch? Hit it with a hot hair dryer/heat gun? Anyone know what the two temp dials should be set to? Scottscoaled suggested that the right one should be at/near 160. What about the left one?

When we left the stove yesterday afternoon, it was functioning just fine, save the circulation fan. The wall thermo was calling for heat just fine, and was stopping the heat once the room reached temps. The auger/comb fan were working great, doing what they should when they should. Not sure what the hold fire timer was doing just yet; we'll address that once we get this circulation fan dialed in. The stove was radiating heat very nicely, and we put a box fan near the stove to help move the warm air further into her home. She was very pleased to have even that, and I was confident that she would have SOMETHING to help keep her warm during these freezing cold temps that we've been having. (As a side note, did I mention that she was heating with her electric stove when we walked in? The oven door was open and the top burners were glowing red. Yikes - that's not safe/affordable at all. This whole scenario makes me VERY thankful for you guys and your help!)

Once we get that limit switch right where we want it (functional and set for correct temps), then she ought to be ready to go for the duration of the winter, right? I'll take a look at the hold fire timer, but I'm betting it's trucking along like the rest of the stove.

Is there any way that this new double pole/double throw switch is a bad choice, simply because it's a smaller amperage switch?

The switch we pulled out was a double pole/double throw but a 15 amp (at 125 volts a.c.).

The only thing we could find to install in its place is a double pole/double throw 10 amp (at 125 volts a.c.).

I just spoke with the stove owner and she says it operated all night, but it sounds like it was only working in "hold fire" mode. She said it would come on for about 3 or 4 minutes per hour (that's how she described it to me). She contends that it's just not right (and it may not be - I have no idea...but I believe that the switch is still ok as is).

She also said the "experienced stove guy" mentioned that the reason he wasn't able to repair the switch was that no switch he could find on such short notice would carry the electricity necessary to properly operate the stove. Could that be true?

If that's the case, I will order the correct switch first thing tomorrow. I don't see how that's the case, though. Wouldn't the smaller-amp switch still work, but only fail sooner? Or would it just partially function? I don't know enough about stoves/switches/electricity to make any education decisions.

Ugh. This is starting to wear me down. Feel like I'm spinning my wheels with this all. Not sure if she even actually knows how the stove is supposed to operate, much less what it's doing now. Just trying to keep her from freezing over there.

Thanks again for all your input. It's been invaluable.