Water heater woes
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