no hot water now

Hello,
I have a hot water heater that the pilot light will not stay lit. I am able to light it, it heats the water and then goes out... I think? I don't know anything about how it really works. Anyway, I have been to this site and read that it could very well be my thermo coupler. I came home and my step-father had gone and bought a universal coupler and replaced it, and it didn't light at all. He replaced it with the old one and it doesn't light at all now either. He is not a plumber but is capable of fixing things. Now he says the guy said it might be the temp. control thing?? I don't want them making mistakes. I was at least able to make hot water when I needed it, now I have none at all. Help!

The only thing I know for sure about gas hot water heaters is that if it will not stay lit after releasing the button for the pilot light then the thermocouple is probably the problem.... if it is positioned in the flame properly then there is something else wrong if it will not stay lit. You are saying that now it will not light at all. Do you smell gas? Any reason for air to be in the line? If so, then maybe your line needs to be purged (open up to get the air out). Be sure to allow the gas to dissipate before striking a match. If the terminal of the thermocouple is not making good contact then it will not allow the pilot light to work right. Is there a possibility the gas was turned off at a valve then not turned back on? Have you paid your gas bill lately?

thanks randy

He said he did all that. I suggested maybe the couple was bad that he bought. He is going to get another one and try again. It has to be the couple. How could the temp control unit, knob thing be the problem?
thanks for replying.

I'm not all that familiar with gas appliances...hopefully someone else will be able to answer. If it will not light at all then the problem is not necessarily the thermocouple.... it only allows it to stay lit. I do know that some appliances have a safety feature that shuts off the gas if there is a leak or carbon monoxide problem. If it will not light at all then something is keeping gas from coming out... clogged orifice? There are a few possibilities and someone besides me could better answer those questions.

You could try another thermocouple but it sounds like the gas valve needs replacing. What is the Brand name of the heater? How old is it?