water heater pilot not staying on

[chamba]

I have a GE gas water heater and the pilot is not staying on. I measured the voltage at the thermocouple. It is 13-15 millivolts but I don't know what the right voltage is. Any way to test the valve before replacing it?

[KField]

I actually don't know the holding voltage for the valve but I would just replace the thermocouple anyway. It is most probably the source of the trouble. You could measure the millivoltage of the new one to know how different it is.

Ken

[chamba]

Thank you Ken. That is just what I did. new one is 22 millivots and it works fine. Problem solved.

[mbk3]

I am assuming you took an open read on the tcouple. I have seen many with open reads of 20-22 and closed read of 0-1. Most safeties (power unit or magnet) hold down to 2 m.v. as long as they are good. It is always best to install an adapter to test tcouples. (closed read)

[KField]

What kind of adapter? It would be nice to read them before replacing if it was easy. I usually replace when the pilot won't stay lit and it seems to take care of it, but that's a trial and error method and I would like to know your measurement method.

Ken

[mbk3]

Hi Ken Yes it is easy. Johnstone Supply has tcouple adapters in catalog #195 part #H23-226 $9.36 cheap. Ok here we go. Unscrew tcouple from control, install adapter and install tcouple. Now take a meter with dc voltage and put one lead on the little post on the adapter and the other lead on the tcouple lead (copper). Light pilot,if pilot stays on then let meter settle on voltage, make note of voltage. This is called "load read". To test safety or magnet, blow out pilot and make note of when you hear the safety dropout or close. Most people only take an "open" read which is merely unscrewing tcouple, holding button down,lighting pilot and putting meter on the tcouple body and the lead tip end. A new tcouple open read will be 25-30m.v Most under load reads on the same tcouple will be around 13-14. The dropout read of ANY control(using tcouple) should 1-3. If higher safety starting to fail. Hope this helps. I probably left something out??

[KField]

Thanks for the info.

Ken