Our pilot light went out and we could not get it to relight. A plumber came out, replaced a short tube and lit it. However, we could not get truly hot water until we turned it up as high as it would go. Two days later the light went out again and we got it relit this time. It is not in a drafty place and it has not been windy. Any idea about what the true problem is?

Check you bill to see what he installed, sounds like a thermocouple. Is this propane or NG?

I think it was a theramocouple (copper piping) and it is natural gas.

When you get the pilot lighted what color is the flame? Can you see the flame touching the thermocouples tube? Amazon.com: Camco 9253 RV 12" Thermocouple Kit: Automotive That is the silver part at the end.

Flame is blue. Yes, it is touching the 2" long silver "sleeve" at end of copper tubing.

Call the same plumber back and tell him his fix is not working. He should stand behind his work.

Also, make sure the vent w/o obstructions and your heater vents ( on the bottom ) are not blocked.

What brand of heater is it ? GE from Home Depot ?