Another old stove- Any ideas?

[MurphCT]

Hello Folks.

I'm out of ideas on some trouble I'm having with an old Earth Stove.

Had it now for a second year- first year it worked fine and now it has a problem.

Frankly, I could not figure it out and could not find anyone with any knowledge of the stove, so I've been replacing parts.

I replaced a low limit switch, and a high limit switch for the auger.

I have also replaced the control board.

This is an old stove, a model MP240.

The stove goes through the start up procedure fine but never starts cycling on and off.

The auger feeds constantly until the stove shuts off- I assume the high limit switch is tripped.

Anyone have any ideas?

Murphy

 

[kinsmanstoves]

Hello Folks.

I'm out of ideas on some trouble I'm having with an old Earth Stove.

Had it now for a second year- first year it worked fine and now it has a problem.

Frankly, I could not figure it out and could not find anyone with any knowledge of the stove, so I've been replacing parts.

I replaced a low limit switch, and a high limit switch for the auger.

I have also replaced the control board.

This is an old stove, a model MP240.

The stove goes through the start up procedure fine but never starts cycling on and off.

The auger feeds constantly until the stove shuts off- I assume the high limit switch is tripped.

Anyone have any ideas?

Murphy

Is this a used stove or a 2 yr old stove?
I am not familiar with this stove but I would check the wire harness to make sure no one bypassed anything and all connections are clean and connected.

Eric

 

[rayttt]

sounds like its never getting a proof of file so it shuts down..
is there any kind of probe in the exhaust air flow??

 

[MurphCT]

It is a used old stove,. I bought it last year but the manual I have was revised in 4/92 which would make it 15 years old.

Thanks,

Murphy

 

[MurphCT]

Nothing in the manual about a sensor in the exhaust.

There are two low limit switches and two high limit switches.

The low limit switches are tripping because the control board blinks if after start-up, they have not been tripped.

I have to add that the cycling on and off did work once after I installed the new control board but no longer does.

Murphy

 

[kinsmanstoves]

If it starts and goes right out there is some type of sensor inside the stove that is tripped. The high limit (overheat) would work opposite of a proof of fire sensor. Usually there is a snap disk or "eye" sensor somewhere in the stove to tell the control board that the stove is working.

When the stove starts to go out you said the auger still feeds pellets, correct?
What makes the fire go out? Is it the combustion blower stops working?
Is your exhaust clear? When was the last time it was cleaned? Some stoves will go into a shut down if the exhaust is blocked?
Is the door gaskets in place? Some stove have a negative pressure switch to shut them down.

Need some more info on how it shuts down.

Eric

 

[MurphCT]

If it starts and goes right out there is some type of sensor inside the stove that is tripped. The high limit (overheat) would work opposite of a proof of fire sensor. Usually there is a snap disk or “eye” sensor somewhere in the stove to tell the control board that the stove is working.

When the stove starts to go out you said the auger still feeds pellets, correct?

After the start up procedure and the stove is burning, the auger never stops. It just keeps feeding pellets instead of cycling on and off.

What makes the fire go out? Is it the combustion blower stops working?

The stove shuts down when the high limit switch for the combustion blower trips and that stops both the blower and the auger.



Is your exhaust clear?

The exhaust is clear.

When was the last time it was cleaned?

Cleaned it last week.

Some stoves will go into a shut down if the exhaust is blocked?


Is the door gaskets in place? Some stove have a negative pressure switch to shut them down.

The door gasket is in place.

 

[kinsmanstoves]

Have to wait and see what some of the other people say. I am at a loss here.
Maybe it is a Monday Morning Fog but I do not understand.

Eric

 

[MurphCT]

I'll try to clarify the sequence.

I press the start-up button which lights the start up light and starts the auger for a period with no combustion fan.

All stops for 3 minutes to allow for a lighting of the pellets.

Then the combustion fan starts for another period to heat up the stove with no pellet feed.

The start-up light goes off- if the stove is not hot enough, the start up light blinks and no auger feed.

If the stove is hot enough, no blinking start up light and the stove status light will glow red indicating the auger is now running.

The stove is getting hot enough as the auger starts at the end of the start-up sequence.

The stove status light is supposed to alternate between red and green- red for pellet feed, green for no pellet feed.

The stove never stops feeding pellets as it should, cycling pellet feed on and off.

Eventually, the stove overheats and the auger and the combustion fan shut off.

I hope this is clearer.

Thanks,

Murphy

 

[kinsmanstoves]

I'll try to clarify the sequence.

I press the start-up button which lights the start up light and starts the auger for a period with no combustion fan.

All stops for 3 minutes to allow for a lighting of the pellets.

Then the combustion fan starts for another period to heat up the stove with no pellet feed.

The start-up light goes off- if the stove is not hot enough, the start up light blinks and no auger feed.

If the stove is hot enough, no blinking start up light and the stove status light will glow red indicating the auger is now running.

The stove is getting hot enough as the auger starts at the end of the start-up sequence.

The stove status light is supposed to alternate between red and green- red for pellet feed, green for no pellet feed.

The stove never stops feeding pellets as it should, cycling pellet feed on and off.

Eventually, the stove overheats and the auger and the combustion fan shut off.

I hope this is clearer.

Thanks,

Murphy

I press the start-up button which lights the start up light and starts the auger for a period with no combustion fan. Combustion or circulation?
Pellets need the combustion fan or they will not light.

Eric

 

[MurphCT]

Start up procedure starts with feeding of pellets and no combustion. There is no flame in the stove at the beginning.

Builds up the pile of pellets, then stops for three minutes to allow for lighting the pellets.

I light the pellets.

After the three minutes, the combustion fan starts for the first time to allow the fire to build and stove to heat up.

Sorry for the confusion.

 

[kinsmanstoves]

I'll try to clarify the sequence.

I press the start-up button which lights the start up light and starts the auger for a period with no combustion fan.

All stops for 3 minutes to allow for a lighting of the pellets.

Then the combustion fan starts for another period to heat up the stove with no pellet feed.

The start-up light goes off- if the stove is not hot enough, the start up light blinks and no auger feed.

If the stove is hot enough, no blinking start up light and the stove status light will glow red indicating the auger is now running.

The stove is getting hot enough as the auger starts at the end of the start-up sequence.

The stove status light is supposed to alternate between red and green- red for pellet feed, green for no pellet feed.

The stove never stops feeding pellets as it should, cycling pellet feed on and off.

Eventually, the stove overheats and the auger and the combustion fan shut off.

I hope this is clearer.

Thanks,

Murphy

I press the start-up button which lights the start up light and starts the auger for a period with no combustion fan. Combustion or circulation?
Pellets need the combustion fan or they will not light.

Eric

I am sorry I was thinking it had an ignitor.

The stove never stops feeding pellets as it should, cycling pellet feed on and off. With this I would say it is a control board issue. Lets see what anyone else has to say.

Eric

 

[crausch]

I don't know anything about your stove but I would tend to agree with Eric. It seems that the auger would be controlled by the control board. Other switches and sensors can sense heat, vacuum, or photoelectric eyes to sense flame, but I think most of these would alert to faults which would probably stop the auger from feeding. I don't think any would cause continuous feed. I think the logic for controlling the auger must be in the control panel.

But this is just a educated guess ( and I use that term lightly)

 

[MurphCT]

Ok, well the control panel is new so this stove may be toast.

Murphy

 

[rayttt]

well if its a new control board..there are only a few other things..
theres the actual switchs etc...and they should be cheap compared to the board.
depending on the switch it may be able to be jumpered out for troubleshooting purposes.

 

[MurphCT]

I admit I'm pig-headed enough to want to figure this out.

I took out the new control board, put in the old one.

Same problem- auger won't cycle on and off.

Could it be a wiring problem from the control board to the auger?

How could I tell?

The actual switches are part of each control board.

Murphy

 

[crausch]

I guess that means that you either have two good control boards or two bad ones, hmmm?

If it was me I guess I would start testing each of the switches or sensors as rayttt mentions. Perhaps with a multimeter you can determine if specific switches are open or closed. You will need to know their purpose though so that you can determine if their bad or not.

 

[rayttt]

one of the switchs is probably a pressure switch..which is probably not turning on..
due to air leaks..like gaskets etc..
Id find the pressure switch and if you have a multimeter..Id measure the voltage on it...presumably there will either be 120 vac across it or zero volts..then with the stove on and running ,...when u close the door...and pressure is obtained the switch will switch to the opposite

some will allow you to bypass the switch with a jumper...but without a schematic..there is no way to know if this stoves switch can be safely jumpered for testing.

If it were me and MY stove...id find the pressure switch and with the stove unplugged from the wall..Id'd jumper the switch with an alligator clipped jumper and see if that fixs the problem...however Im used to working with electronics and household voltages etc to know the dangers.