What is the difference in thermocouples....

[rob air]

Working on a gas fireplace that has a 750 millivolt generator and a seperate thermocouple for the pilot. Pilot wont stay lit.

What is the difference in thermocouples for gas firplaces verses a furnace?
The gas firplaces i've seen have pointy tips and seem smaller in diameter.

Can i use a universal thermocouple to replace the pointy tip one?

Do they have the same voltage output as the "standard thermocouples readily available"

[hearthman]

While they may be 30 millivolt and have the same thread, they can have varying dropout rates. No, you should only use the thermocouple from that mfr. Using other than OEM can void the warranty and listing and may pose a real hazard.

[scubasteve54016]

the universal will not fit right in the assembely and you will not get the tip to be in the flame like you need. The reason you need the right one is for safety reasons. the thermocouple needs to shut off the gas within 4 seconds of flame loss.

[gasguy]

The 'pointy tip' t-couples are quick-dropout ones. Regular ones should dropout within 90 sec, and QD ones are under 20 sec. Do not install a regular t-couple in place of a QD one.

[rob air]

Thanks for the info.
I thought there would be a difference, just didn't know what it was.
Local furnace supply companies don't have these in stock for some reason?
You would think there is a demand for them.

I ordered two from Johnstone Supply, and they have to ship them in too.

Learn something new everyday..........

[hearthman]

keep in mind the dropout rate of a pilot is controlled by the construction of the TC, the flame temp. and the bracket the pilot mounts in. If you change TCs or pilot brackets, you change the dropout rate and void the warranty. I would not get my parts from HVAC supply houses. Get them OEM or not at all.

[SeattlePioneer]

I often cursed the seemingly enormous variety of thermocouples out there. I used to joke with customers by telling them they must have the Bugalrian national standard thermocuple in their equipment, and I could replace it for them as soon as I could get the needed replacement part from a Bulgarian fireplace supplier.


Somehow my customers sometimes failed to see the humor.

[logdoc_rob]

Now that's funny !!!!