thermocouple melted....

[dogdog]

Trying to prep for Winter..... and doing the water change/flush on the boiler. Found the thermocouple was melted.... still works keeping the pilot on... think I should be changing it and not get caught dead in the Winter scrambling to get heat.

Now the question is.

This is a new universal thermocouple one from Lowes, forgot what brand... only 1/2 season 6 months or less on this continuous pilot, I shut off gas in Summer.... is there a common cause for this?

 

[bonneyman]

The Chinese invasion hits again! Thermocouples have a hard life - I'd like to look so good after being in a flame 24/7 for months on end!

But since most furnaces have gone to electronic ignition, there remains fewer applications for old style thermocouples. And most are not USA made.

I try and buy up all the new old stock thermocouples I come across. Never know when I'm gonna need one. Tell me what length you need, and I'll break out my winter stash (early!) and see if I have one for you.

 

[Ironhorse74]

Are you on propane? A while back we were having problems on our equipment with melted thermocouples. We could actually map the problem out. Started having dealers send in botyles of propane. We then clocked the propane in our lab. All of the propane was hot. Some as high as 150k btu per gallon.

Brad

 

[dogdog]

The Chinese invasion hits again! Thermocouples have a hard life - I'd like to look so good after being in a flame 24/7 for months on end!

But since most furnaces have gone to electronic ignition, there remains fewer applications for old style thermocouples. And most are not USA made.

I try and buy up all the new old stock thermocouples I come across. Never know when I'm gonna need one. Tell me what length you need, and I'll break out my winter stash (early!) and see if I have one for you.

Lol Thx Bonneyman, not sure if that is the COO thing, though I didn't pay attention to the COO just open package and install.....was hoping it is not my mistake of setting the thermocouple too close to the flame etc. then again... this same brand thermocouple running on the hot water heater (125K Btu) had no issues 24/7 365, on the boiler it's only the winter months, The rest of the season I shut the gas completely to this unit......

Are you on propane? A while back we were having problems on our equipment with melted thermocouples. We could actually map the problem out. Started having dealers send in botyles of propane. We then clocked the propane in our lab. All of the propane was hot. Some as high as 150k btu per gallon.

Brad

Its Natural Gas ......the boiler it's a Burham IND-8 250K BTU rated with continuous Pilot Flame but shouldn't matter right? Only the pilot flame hits the tip of the thermocouple., Only tip area is what it looks like melted... will have to pull it tomorrow.... it still works , means it still kept the pilot lite when I try to lite it. But just don't want to caught dead in the winter without heat, so not an emergency emergency but would like to know if it is a setting adjustment or just cheap parts., some site when google suggest it's blocked chimney, etc but that is not the cause. it's 10" chimney old style that is big enough to accommodate 500K btu, some suggest it's some sort of block orifice? not sure.

 

[bonneyman]

A thermocouple should be installed so about 3/8" of an inch or so is fully engulfed by the flame. More than that the tip starts to oxidize and break down.

Yeah, propane has about twice the BTU value as the same amount of natural gas. Might want to check your pilot orifice. If it's a NAT one and you're running LP gas you're hitting the thermocouple with two times the amount of heat.

 

[inphx]

Sorry to pile on the thread but i am trying to prep my moms furnace - its 20 plus yeas for sure janitrol. the flame sensor is a mechanical bimetal rod that closes a switch... can i use the common $10 flame sensor and mount it into the flame safely?

Original:

Replacements:

Is it a case of mounting the tab and end isolated from the metal frame and then wiring it to the current switch wires? Is this a common safe retrofit?

 

[dogdog]

A thermocouple should be installed so about 3/8" of an inch or so is fully engulfed by the flame. More than that the tip starts to oxidize and break down.

Yeah, propane has about twice the BTU value as the same amount of natural gas. Might want to check your pilot orifice. If it's a NAT one and you're running LP gas you're hitting the thermocouple with two times the amount of heat.

Replaced with the one from HomeDepot today... HoneyWell brand there is no adjustment for these things, and the flame hits the same spot. It works and stays on.... when I compare these universal to to the original that came with the boiler the original one have a shorter tip... not sure if that makes a differences.

Anyways here is the pic of this.... I know it is definitely from Lowes, cause I got it as an emergency at 10:58PM last Winter.....not sure in this case if it is cheap part or just too hot flame, there are no adjustment to the stick out.....at least not with this.

 

[rlitman]

Sorry to pile on the thread but i am trying to prep my moms furnace - its 20 plus yeas for sure janitrol. the flame sensor is a mechanical bimetal rod that closes a switch... can i use the common $10 flame sensor and mount it into the flame safely?
...Is it a case of mounting the tab and end isolated from the metal frame and then wiring it to the current switch wires? Is this a common safe retrofit?

No! That replacement thermocouple does not act like a switch. It will not function.

 

[dogdog]

Sorry to pile on the thread but i am trying to prep my moms furnace - its 20 plus yeas for sure janitrol. the flame sensor is a mechanical bimetal rod that closes a switch... can i use the common $10 flame sensor and mount it into the flame safely?

Original:

Replacements:

Is it a case of mounting the tab and end isolated from the metal frame and then wiring it to the current switch wires? Is this a common safe retrofit?

If the parts are no longer made, then I would call the manufacture and confirm with them with is the alternate part number to use...... the replacement part you posted work just like these thermocouple it produces a current. Not sure how your original works.....I wouldn't skim a pretty penny on safety.....

 

[Ohmthis]

Dogdog, you may need to turn the pilot flame down. A thermocouple should last several years .if the flame it too much (too hot) it will shorten the life of them.

 

[dogdog]

Dogdog, you may need to turn the pilot flame down. A thermocouple should last several years .if the flame it too much (too hot) it will shorten the life of them.

Hmmm never knew there was adjustment for the pilot flame is it at the nozzle or at the gas unit? their service manual only mention using a different nozzle if it is higher elevation areas. nothing about sea level.

this is the manual.

https://file.ac/9IIdhbTJLLQ/Independence I&O.pdf


O- nvm thanks, will check.... man can't see things clearly at 4AM. Thanks Ohmthis.

 

[zmaxmotorsports]

Sorry to pile on the thread but i am trying to prep my moms furnace - its 20 plus yeas for sure janitrol. the flame sensor is a mechanical bimetal rod that closes a switch... can i use the common $10 flame sensor and mount it into the flame safely?

Original:

Replacements:

Is it a case of mounting the tab and end isolated from the metal frame and then wiring it to the current switch wires? Is this a common safe retrofit?

Send me the model number off the furnace and Ill check johnstone for ya.

 

[Ohmthis]

Dogdog, this is on a furnace and I'm not sure what your brand or model number gas valve, but it shows what I'm talking about. Also the main gas pressure could be high. If you want to check that, you need a manometer (you can make one really cheap, look on the web) and there are tutorials to help. If you need help finding anything just shout. Also put the model of boiler and gas valve you have. That could help us down the road if anyone has the same issues. issues.

 

[Ohmthis]

****, sorry I forgot the link!

 

[bonneyman]

Sorry to pile on the thread but i am trying to prep my moms furnace - its 20 plus yeas for sure janitrol. the flame sensor is a mechanical bimetal rod that closes a switch... can i use the common $10 flame sensor and mount it into the flame safely?

Original:

Replacements:

Is it a case of mounting the tab and end isolated from the metal frame and then wiring it to the current switch wires? Is this a common safe retrofit?

If you need a mechanical close pilot switch then one like this is what you need.

http://www.americanhvacparts.com/p-13965-2-wire-pilot-flame-sensor-robertshaw-gaffers-sattler.aspx

But on a 20 year old furnace you really should have a licensed contractor come out and inspect it, clean it, and check the heat exchanger.

 

[dogdog]

Dogdog, this is on a furnace and I'm not sure what your brand or model number gas valve, but it shows what I'm talking about. Also the main gas pressure could be high. If you want to check that, you need a manometer (you can make one really cheap, look on the web) and there are tutorials to help. If you need help finding anything just shout. Also put the model of boiler and gas valve you have. That could help us down the road if anyone has the same issues. issues.

The boiler is Burnham Independence series IN-8 245K BTU older (2008) continuous pilot unit service manual is in the link. the gas valve is the honeywell mention in the pic. very rock solid unit for steam heating.... except for this pilot thing started last year and some other minor over pipe dope clogging by the installer....

I will check the orifice and that gas pilot adjustment.. and see how it goes... good thing about doing these type of maintenance early just in case replacement parts are hard to find. As far as ManoMeter..... this thing probably had no idea how to use it....... I know the gas piping is 1.5 inch black pipe or maybe its 1.25" then turn down to 1" for burner and 3/4 for the hotwater heater. Gas meter is upgrade to accommodate..

Thanks folks for the pointers.

 

[dogdog]

3 years or 2 Winters. .... trying to prep for Winter and doing the maintenance... the pilot won't stay on... this is about 2 Winter season out of this thing... hmm ... not sure if it is because I shut down the gas during Summer time... and let it corrode/oxidated or something....

 

[SALIV8]

You can test the thermocouple voltage that its producing to see if it's bad. There's a chemical reaction that produces small voltage and sends to gas valve. May also be a bad gas valve depending on the age of valve.

 

[dogdog]

Just finished changing in a universal one in, all good now... had to cut the old one to re-used the nut.... just weird these things goes bad so often... the same one that was in the gas water heater is still good, same brand as the one in the gas boiler...not sure if it is something I did or what nots...

BTW what is the voltage it is suppose to be producing under a flame?

 

[LS6 Tommy]

Sorry to pile on the thread but i am trying to prep my moms furnace - its 20 plus yeas for sure janitrol. the flame sensor is a mechanical bimetal rod that closes a switch... can i use the common $10 flame sensor and mount it into the flame safely?

Original:

Replacements:

Is it a case of mounting the tab and end isolated from the metal frame and then wiring it to the current switch wires? Is this a common safe retrofit?

That will not work. It is used in a flame rectification system. You have a thermostatic bimetal switch.

Tommy

 

[Jim greengo]

Sorry to pile on the thread but i am trying to prep my moms furnace - its 20 plus yeas for sure janitrol. the flame sensor is a mechanical bimetal rod that closes a switch... can i use the common $10 flame sensor and mount it into the flame safely?

Original:

Replacements:

Is it a case of mounting the tab and end isolated from the metal frame and then wiring it to the current switch wires? Is this a common safe retrofit?

I'd have the heat exchanger checked before you dump too much time into it.