NPS40 help

[SmokeyTheBear]

ambene,

If you have some electrical tape around we can further verify that is the problem.

That 160 degree snap disc that is showing up as always closed can be removed from the circuit by placing electrical tape on the lead you removed to do the continuity test and the stove manually fired at a low heat level setting, allowing the stove to come to temperature the blowers and auger should operate and then turning the stove off.

It should proceed to normal shut down.

Did you also do the test with the 140 degree snap disc?

I did not do the test with the 140 but I will now. A question, if I remove the 160 disc completely from a cold stove, shouldn't the stove shut off?

I don't know what the logic being used by the controller is.

The controller has to see things the way it expects them to be and also in the order they open and close.

Most stoves use only one switch to indicate fire in the device, this is why I asked about the 140 degree switch in particular as that is normally the one that indicates a fire in the stove.

At the moment I'm only interested in switch states.

 

[ambene]

ambene,

If you have some electrical tape around we can further verify that is the problem.

That 160 degree snap disc that is showing up as always closed can be removed from the circuit by placing electrical tape on the lead you removed to do the continuity test and the stove manually fired at a low heat level setting, allowing the stove to come to temperature the blowers and auger should operate and then turning the stove off.

It should proceed to normal shut down.

Did you also do the test with the 140 degree snap disc?

I did not do the test with the 140 but I will now. A question, if I remove the 160 disc completely from a cold stove, shouldn't the stove shut off?

I don't know what the logic being used by the controller is.

The controller has to see things the way it expects them to be and also in the order they open and close.

Most stoves use only one switch to indicate fire in the device, this is why I asked about the 140 degree switch in particular as that is normally the one that indicates a fire in the stove.

At the moment I'm only interested in switch states.

I have my switches mixed up, I was looking at pictures instead of the blow up diagram. When applying the multimeter leads to the 160 switch (mounted against the firebox) the multimeter never moves from 1 no matter where I place the leads. I removed one purple wire to test it and then the other, neither moved from 1. When applying the multimeter leads to the 140 switch, (mounted against the combustion blower assembly) this is the switch that reads all over the map and then returns to zero.

 

[SmokeyTheBear]

ambene,

If you have some electrical tape around we can further verify that is the problem.

That 160 degree snap disc that is showing up as always closed can be removed from the circuit by placing electrical tape on the lead you removed to do the continuity test and the stove manually fired at a low heat level setting, allowing the stove to come to temperature the blowers and auger should operate and then turning the stove off.

It should proceed to normal shut down.

Did you also do the test with the 140 degree snap disc?

I did not do the test with the 140 but I will now. A question, if I remove the 160 disc completely from a cold stove, shouldn't the stove shut off?

I don't know what the logic being used by the controller is.

The controller has to see things the way it expects them to be and also in the order they open and close.

Most stoves use only one switch to indicate fire in the device, this is why I asked about the 140 degree switch in particular as that is normally the one that indicates a fire in the stove.

At the moment I'm only interested in switch states.

I have my switches mixed up, I was looking at pictures instead of the blow up diagram. When applying the multimeter leads to the 160 switch (mounted against the firebox) the multimeter never moves from 1 no matter where I place the leads. I removed one purple wire to test it and then the other, neither moved from 1. When applying the multimeter leads to the 140 switch, (mounted against the combustion blower assembly) this is the switch that reads all over the map and then returns to zero.

The one on the combustion blower is the one that is causing you the trouble, it should close only after the temperature reaches 140 degrees and it is likely supposed to open at 120 degrees.

I'd order a new 140 degree switch and if you can get a ceramic one. They generally last longer.

The 160 degree switch appears to be the one that causes the convection blower to go to high speed if needed.

I don't like telling folks to remove wires while a stove is running it is just too dangerous. But if the fan runs the moment you plug the stove back in, then you can insulate one of those leads on the 140 degree switch when the stove is unplugged and cold and then plug the stove back in. That should stop the fans.

I have a healthy respect for electrical devices and observe some rules that seem funny to others.

Been bit by devices that have been powered off and unplugged before.

 

[ambene]

ambene,

If you have some electrical tape around we can further verify that is the problem.

That 160 degree snap disc that is showing up as always closed can be removed from the circuit by placing electrical tape on the lead you removed to do the continuity test and the stove manually fired at a low heat level setting, allowing the stove to come to temperature the blowers and auger should operate and then turning the stove off.

It should proceed to normal shut down.

Did you also do the test with the 140 degree snap disc?

I did not do the test with the 140 but I will now. A question, if I remove the 160 disc completely from a cold stove, shouldn't the stove shut off?

I don't know what the logic being used by the controller is.

The controller has to see things the way it expects them to be and also in the order they open and close.

Most stoves use only one switch to indicate fire in the device, this is why I asked about the 140 degree switch in particular as that is normally the one that indicates a fire in the stove.

At the moment I'm only interested in switch states.

I have my switches mixed up, I was looking at pictures instead of the blow up diagram. When applying the multimeter leads to the 160 switch (mounted against the firebox) the multimeter never moves from 1 no matter where I place the leads. I removed one purple wire to test it and then the other, neither moved from 1. When applying the multimeter leads to the 140 switch, (mounted against the combustion blower assembly) this is the switch that reads all over the map and then returns to zero.

The one on the combustion blower is the one that is causing you the trouble, it should close only after the temperature reaches 140 degrees and it is likely supposed to open at 120 degrees.

I'd order a new 140 degree switch and if you can get a ceramic one. They generally last longer.

The 160 degree switch appears to be the one that causes the convection blower to go to high speed if needed.

I don't like telling folks to remove wires while a stove is running it is just too dangerous. But if the fan runs the moment you plug the stove back in, then you can insulate one of those leads on the 140 degree switch when the stove is unplugged and cold and then plug the stove back in. That should stop the fans.

I have a healthy respect for electrical devices and observe some rules that seem funny to others.

Been bit by devices that have been powered off and unplugged before.

I will have to do more research on the ceramic switch - I've just been looking for the last 30 min and can't find one. I will ask the technician I had over before if he can order one. I've ordered my switches and thank you for the suggestion. I will go buy some electrical tape and complete the test on the 140 switch. I would not do it if I didn't feel comfortable and I think all should be fine thus far. I'll post the results.

 

[j00fek]

i had this same exact problem at the beginning of the burning yr. i had to change out the same switch and ignitor. the switch popped out of the round hole it was in and was visibly melted and the round metal piece was off of it.

the ignitor had burnt a hole through the metal housing and was not fun pushing/pulling out of the hole. replaced both parts and the stove is still hummin along.

 

[ambene]

ambene,

If you have some electrical tape around we can further verify that is the problem.

That 160 degree snap disc that is showing up as always closed can be removed from the circuit by placing electrical tape on the lead you removed to do the continuity test and the stove manually fired at a low heat level setting, allowing the stove to come to temperature the blowers and auger should operate and then turning the stove off.

It should proceed to normal shut down.

Did you also do the test with the 140 degree snap disc?

Hi Smokey, I removed one of the wires from the 140 limit switch and covered the exposed metal connector with electrical tape. I plugged the stove back in and the exhaust fan came on as usual. I built a medium fire manually using gel. I let the fire burn (with convection fan & auger switches turned on) for about 30 minutes and then shut down the auger control and the convection fan control. Usually the stove shuts off in 15-ish minutes. It's now 40 minutes past and the exhaust fan is still running. I also took a picture of my handywork to make sure I didn't misunderstand your instructions. One wire is still connected to the upper right screw securing the sensor. The lower left screw is open and the wire (lead) I removed is to the left - black wire, red sleeve and black electrical tape.

 

[ambene]

i had this same exact problem at the beginning of the burning yr. i had to change out the same switch and ignitor. the switch popped out of the round hole it was in and was visibly melted and the round metal piece was off of it.

the ignitor had burnt a hole through the metal housing and was not fun pushing/pulling out of the hole. replaced both parts and the stove is still hummin along.

That does not sound fun at all! I have just purchased all new replacement switches and an ignitor to be sure I'm covered for parts. I did remove the 140 degree switch and it didn't look bad - it had some build up on it which I cleaned off and over all it looked fine. As Smokey is indicating the thing seems to be stuck or something. I appreciate your taking the time to send me your experience - I hope this thread helps the next 'newbie' like me, that comes along.

 

[SmokeyTheBear]

You could do the same thing with the 160 but keep the low limit the way you have it.

Just do not fire it for any length of time.

You might also want to just remove that 140 and recheck it with your meter again (btw that low limit is a ceramic unit from what I'm seeing in your picture).

You could have a bad controller.

ETA: The 140 being disconnected should have shut things off if the controller is good as soon as the stove came out of start up.

 

[ambene]

You could do the same thing with the 160 but keep the low limit the way you have it.

Just do not fire it for any length of time.

You might also want to just remove that 140 and recheck it with your meter again (btw that low limit is a ceramic unit from what I'm seeing in your picture).

You could have a bad controller.

ETA: The 140 being disconnected should have shut things off if the controller is good as soon as the stove came out of start up.

Hi Smokey, here is the latest update:

I removed a lead from the 160 (left the 140 lead off and covered with electrical tape). I fired up the stove for about 30 min and shut it down. 30 min later & cool-er to the touch, the exhaust fan continues to blow. What is interesting though is that I heard sounds a couple of times like a switch or something was 'trying' turn off (I assume) the exhaust fan. It was a noticeable click and I suppose it could have been a contraction noise as the stove cooled down, but it didn't sound like it.

In any case I've ordered both 140 & 160 replacements and if these don't work I will order a controller. As the controllers can't be returned once purchased, I have my fingers crossed either switch replacement will make a difference.

Also I applied the multimeter to the 140 switch after I disconnected one of the purple 160 wires. Interestingly, the reading on the 140 changed, it is now all over the map and then goes to 1 (instead of 0 as before). I hold the multimeter leads on the rivets for about 40-45 seconds.

 

[SmokeyTheBear]

Hi ambene,

A few things about taking resistance readings the meters are very sensitive and will go all over the place if you move the probes, they also take time to function.

If you have a flakey switch it can cause problems for a controller (repeat state changes can cause the controller to act funny and even fry some parts).

But the switches are a lot cheaper than a controller.

I don't know if Dave Gault of Wood Heat Stoves has a technical manual for your unit, it might be worth a PM to him, include in it your stove model, serial number, your email address, and request a copy of the technical (service) manual. You'll be miles ahead of the game. Dave has been kind enough to provide manuals to people trying to fix problems with their stove.