A customers 70 gallon gas fueled Bradford White water heaters' pilot light goes out immediately after releasing the red pilot button when relighting it. I concluded (in order of most likely suspects) the thermocouple which was replaced. No change. I figured next it could be a clogged orifice (not likely), but pulled the burner anyway to clear the tube. No clogs and no change. Gas supply is strong. No blockage in the exhaust vent.
This is a model that is 8 years old. It's most likely past the its' life expectancy. The customer has left the decision to repair or replace up to me. A similar model will cost $1200 plus my labor to replace. If I wanted to repair it and wanted to order a part would I be correct in assuming that the thermostat valve is what's preventing the pilot from staying lit? I will most likely replace the unit, but would like to know if my guess about the repair is correct?