Cleaning thermocouple on furnace.

[okrattler]

My furnace is blowing cold air and the thermocouple is dirty. All I have is P80 grit sandpaper. Shouldn't hurt to clean it off with that should it as long as I don't overdo it? I gotta get this thing runnin right before tonight. It's gonna get colder than a well diggers *** later and I ain't gonna battle the cold tonight if I don't have to.

[SJP51]

Steel wool would work better. 80 is kind of course.

it's usually just soot. You could try a q-tip with alcohol.

[Walker]

Sure you can clean it the working mechanicals are inside. Unless there is a newer technology there is a bi-metal switch inside. Cleaning the outside probably won't work.

[okrattler]

I thought I had some steel wool but I don't guess I do. I'll see if I can find some alcohol.

The last time this happened I had a buddy come check it out and he ran some steel wool over it and put it back in there and it worked. He said I should clean it every so often.

[hot_rod_eddie]

[QUOTE=Walker;16019893]Sure you can clean it the working mechanicals are inside. Unless there is a newer technology there is a bi-metal switch inside. Cleaning the outside probably won't work.[/QUOTE

Agree. Following Only way cleaning would be effective would be a few degrees. Even grounded thermocouples are grounded inside.

https://www.omega.com/en-us/resources/thermocouple-hub

Good luck OP and let us know what you find.

[Dale Moser]

Steel wool is the way to go, and it can definitely help, especially with propane. If it’s not sooted up, it likely won’t help though.


Sent from my iPhone using Tapatalk

[Dale Moser]

Sure you can clean it the working mechanicals are inside. Unless there is a newer technology there is a bi-metal switch inside. Cleaning the outside probably won't work.

It’s not really a switch. A bi-metal thermocouple is just one type of metal inside another type of metal. It makes milivolts of electricity when heated, that hold open a valve after you’ve manually opened the valve,(via pushing in the button) via a small magnet. There are no moving parts inside a thermocouple, and they work better, the hotter they get.


Sent from my iPhone using Tapatalk

[critter69]

¡

Sure you can clean it the working mechanicals are inside. Unless there is a newer technology there is a bi-metal switch inside. Cleaning the outside probably won't work.

This, normally cleaning a thermal couple doesn’t work, now cleaning a flame sensor normally does. You can get a new thermal couple at Home Depot or Lowe’s for around 8-9 bucks.

[hot_rod_eddie]

It’s not really a switch. A bi-metal thermocouple is just one type of metal inside another type of metal. It makes milivolts of electricity when heated, that hold open a valve after you’ve manually opened the valve,(via pushing in the button) via a small magnet. There are no moving parts inside a thermocouple, and they work better, the hotter they get.


Sent from my iPhone using Tapatalk

A thermocouple has two wires of dissimilar metals welded together at the hot junction. A dirty probe would only change the temp a few degrees.

OP - Is that the problem or no heat at all ( like probe not reading)?

PS - how does propane produce soot? The A/F would have to be way off.

[hot_rod_eddie]

¡

This, normally cleaning a thermal couple doesn’t work, now cleaning a flame sensor normally does. You can get a new thermal couple at Home Depot or Lowe’s for around 8-9 bucks.

https://www.serviceexpertsmemphis.com/blog/what-a-flame-sensor-is-and-why-it-matters

[hot_rod_eddie]

https://legacyac.com/what-to-do-with-a-dirty-flame-sensor/

Sorry to highjack your thread, I just couldn't get my head around cleaning a thermocouple.

[okrattler]

¡

This, normally cleaning a thermal couple doesn’t work, now cleaning a flame sensor normally does. You can get a new thermal couple at Home Depot or Lowe’s for around 8-9 bucks.

I had it mixed up with the thermocouple. But you're right. It was the flame sensor he cleaned last time. That's been so long ago I was thinkin it was the thermocouple. I had no choice but to go over the sensor with that sandpaper I had pretty lightly and put it back in. But the good news is that it works just fine now. May have scratched it up some with that sandpaper but it got it cleaned.

Sorry. I was confused about what I was supposed to clean. Had my terminology mixed up.

I've had so many dadgum problems with this furnace it's hard to keep everything straight. The thermocouple has given me problems a few times so that's probably why I was thinkin that instead of the flame sensor.

[hot_rod_eddie]

I had it mixed up with the thermocouple. But you're right. It was the flame sensor he cleaned last time. That's been so long ago I was thinkin it was the thermocouple. I had no choice but to go over the sensor with that sandpaper I had pretty lightly and put it back in. But the good news is that it works just fine now. May have scratched it up some with that sandpaper but it got it cleaned.

Sorry. I was confused about what I was supposed to clean. Had my terminology mixed up.

I've had so many dadgum problems with this furnace it's hard to keep everything straight. The thermocouple has given me problems a few times so that's probably why I was thinkin that instead of the flame sensor.

Good news. Thanks for the update.

[Dale Moser]

A thermocouple has two wires of dissimilar metals welded together at the hot junction. A dirty probe would only change the temp a few degrees.

OP - Is that the problem or no heat at all ( like probe not reading)?

PS - how does propane produce soot? The A/F would have to be way off.

The A/F gets off when dust, bugs, etc, block the Venturi hole that draws in air. What the hell do I know, I’ve only worked on a couple thousand thermocouples.


Sent from my iPhone using Tapatalk

[okrattler]

The A/F gets off when dust, bugs, etc, block the Venturi hole that draws in air. What the hell do I know, I’ve only worked on a couple thousand thermocouples.


Sent from my iPhone using Tapatalk

That's good that you've done a lot of it cause I may need more help with this thing in the future. Thank the Lord I got it working again. The temperature right now is 6 degrees. Plenty cold enough for me.

The temperature tonight is supposed to be....well.....0. So in the words of Ron White "There's not one." I drove past a cow dusted in snow today and I was sure glad I had the heater blowing on me. That old gal looked miserably cold.