I couldn't find a category for water heaters so I'll put this here. I have a 40 gallon gas water heater (not sure of the brand) that seems to have a failing thermostat. Over the months, I keep turning the water temperture setting up and up. Each time I do this I've got nice hot water for a few weeks/month before it starts fading to lukewarm again. Now I am almost completely topped out on the adjustment.

Sometimes the first shower of the day is lukewarm and subsquent ones are nice an hot, almost as thought the first shower "woke up" the heater. Other times all the showers are lukewarm to cold.

The pilot light is always on, so the thermocouple seems to be OK. Can the thermostats on these things be repaired (if that's the problem) and if so where does one find the parts? My heater has a gray box near the bottom of the tank where the gas line, temperature setting knob and thermocouple attach. The local Home Depot, where I bought the heater only carries thermocouples and installation fittings. Thanks

Thanks for the reply. The water heater is made by Reliance and is a 50 gallon model and the model number appears to be: 8 50 NKRT971 C. There is a number on the control valve/thermostat assembly as well: 37C73U 640, but I cannot find a manufacturer name on the the valve at all.

Thanks for the reply. The control valve on my water heater looks exactly like this Bradford-White unit I found on ****: (http://cgi.****.com/ws/e...IT&item=360085971032). The number on that **** unit is 37C73U-724 wheras the number on mine is different in the last 3 digits: 37C73U-640. What is the difference? are they interchangeable? They are both for natural gas at 1/2PSI.

Thanks.

I strongly agree use OEM parts only. Changing pilots or TCs can change the dropout rate and void the warranty & listing.

What you are describing here could be sediment in the base of the tank. As sludge builds up, it insulates the tank requiring more and more BTUs to heat the same water. Flush the tank PMI and see if that helps. The entire control can be replaced, which may be ok for a newer tank but if its about 7+ yrs old or especially if the anode rod has never been replaced, you may be better off buying a whole new tank. These will be more expensive because they have the Flammable Vapor Ignition Resistant design but they are also better insulated and more efficient.

BTW, when's the last time anyone inspected the vent connector or chimney?

HTH,

Thermostats in an electric water warmer just control one leg. Force is constantly accessible on one side and will sustain through the component if the component is acceptable. The top indoor regulator supplies capacity to the top component until the highest point of the warmer ranges setpoint. At that point power is hindered to the top component and transferred to the lower indoor regulator. Editor - <a href="https://tanklesswaterheaterexpress.com/">