How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Jerry Your Own Question
Jerry, Service Technician
Category: HVAC
Satisfied Customers: 3360
Experience:  HVAC Technician. Hearth Products Specialty
Type Your HVAC Question Here...
Jerry is online now
A new question is answered every 9 seconds

I have a Waterford free standing heater that looks like a wood

This answer was rated:

I have a Waterford free standing heater that looks like a wood stove. Every spring I turn off the gas and relight the pilot in fall. In 2012 the pilot would not stay lit when releasing the pilot button. Replaced the thermocouple and thermopile and it worked. Now fall of 2013 and pilot will not stay lit again on fall start up. What gives?
Welcome to Just Answer!

Try cleaning off the tip of the thermocouple with plumbers sand cloth, and then tightening the nut were there the thermocouple screws into the gas valve (its a LEFT hand thread, turn it 1/8 to 1/4 of a turn)

If that fails then it is likely a bad gas valve... for some reason, about one in 10 times when you replace the thermocouple, the gas valve fails a little bit later.

It is most likely that you had not tightened the nut where the thermocouple screws in enough though, that is usually due to the small wrench size that tends to slop on the nut...I use vice grips if necessary to get that extra faction of a turn on the nut.

If you choose to rate my advice so far *positively, I hold the question open for any follow up you might need.


Customer: replied 3 years ago.

I've checked the thermocouple and it was tight. It's not a left hand thread by the way. Is the tightening necessary to get electrical contact? What I don't get is this happens 2 years in a row and I remember now that only the thermopile was replaced 2nd time. It seems that the gas valve is not the problem. How do thermopile and thermocouple differ in operation?

Customer: replied 3 years ago.
Relist: Incomplete answer.
The thermocouple is the smaller of the two, and controls only the coil in the valve that holds open the pilot flame. The thermopile is a much larger thermocouple, and actually produces enough voltage to open and close the main burner port inside the valve, this is the one that operates the main flame. In your case, with the pilot flame not holding, it is going to be a thermocouple problem, (or gas valve issue). I would replace the thermocouple. There are different qualities of thermocouples available, and sometimes the tips of the cheaper ones burn completely off.
The above reply should have been posted as an answer, not an info request. Also, to answer your other question about how tight the thermocouple should be..... you are correct, it is a simple electrical connection there and does not need to be tighter than finger tight plus about a quarter turn.
Customer: replied 3 years ago.

OK, that helps. I'm assuming then the thermocouple generates millivolts but I don't understand how because there are no wires like the t-pile has only a copper line from it to the valve. Also, if the valve itself is bad is it repairable or junk?

The thermocouple does generate about 15 to 20 millivolts (when the pilot flame is strong, and touching the top 1/3 of the thermocouple). Make sure you check your pilot flame also.
The outside copper sheath is used as one of the conductors, and the inner part the other conductor. So to test mv on a thermocouple, you would put one lead on the outside and the other lead of your meter on the very end that would screw into the valve.
IF the valve is bad (not likely) then it is not repairable.
Jerry, Service Technician
Category: HVAC
Satisfied Customers: 3360
Experience: HVAC Technician. Hearth Products Specialty
Jerry and other HVAC Specialists are ready to help you