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Help choosing a Thermocouple, please?

After an experience with a thermocouple that would not fit as-shipped at the pilot end (used the screw-in holder from the previous thermocouple), and then a thermocouple that would not fit (threads just would not catch) on the gas controller (Honeywell VR8300A 3500), I realized that I am not yet smart enough about these to get it right consistently. I know I need a 30 mV, 36" thermocouple for the Burnham boiler that runs a single-pipe system in my house. When I looked more carefully today, I saw that, for instance, there seem to be at least three Honeywell thermocouples available from Supplyhouse that fit my limited specifications.

Please suggest how I might choose more wisely. Thanks for your help.


    EBEBRATT-Ed Member Posts: 11,987
    Usually you can buy a universal thermocouple kit that comes with various adapters so it wil fit screw in , snap in etc pilot assemblies
  • Fred
    Fred Member Posts: 8,518
    As @EBEBRATT-Ed says, I use a Rheem universal thermocouple on my Burnham. Home Depot sells them.
    JUGHNE Member Posts: 9,750
    You could take all your parts, new, old etc down to some good hardware store and look for a good match.

    But the connection of the T-couple to the gas valve is AFAIK all universal. That is one threading you do not want to bugger up.
    Aluminum female threads on the gas valve. The tip of the T-couple must seat firmly inside that fitting. Only snug it up lightly with a wrench only after you are certain the threads are started by hand.
  • JohnNY
    JohnNY Member Posts: 2,917
    Just buy a thermocouple and stop thinking about it so much.
    Contact John "JohnNY" Cataneo, Master Plumber for Consulting Work
    Or for plumbing in NYC or in NJ.

    Or take his class.
  • PaulAndrews
    PaulAndrews Member Posts: 1
    Visit Pyrosales as they may be able to help you find the right solution. Visit --> https://pyrosales.com.au/temperature-sensors/thermocouples
    “Science can amuse and fascinate us all, but it is engineering that changes the world.”