I recently moved into a cape cod built in 1949, and the hot water heater (about 4 years old) has started producing only lukewarm water. The water pressure has not diminished, but all of the faucets in the house produce only one temperature in the hot range: slightly warm.
I tried releasing the pressure relief valve, but the water ejected from the heater was the same temperature as the water coming from the facuets. A plumber suggested that I do a couple of things:
1) check the pressure relief valve. Did it. Water ejected. Nothing changed.
2) check for leaks by watching to see if the water meter shows water being ejected from a pipe somewhere in the house. Nothing.
3) check to see if the heater needs to be flushed. I haven't actually tried this myself.
The only complicating factor I can think of is the fact that there are a couple small sections of pipe in the house that are still made of galvanized steel. However, the supplies leading to the heater are made of copper, and all but one of the output pipes going to the faucets are made of copper as well.
The plumber said that it could also be the thermostat. He said that he could, if necessary, provide the thermostat and install it for $350, or he could, if necessary, provide a new heater and install it for $650. Difficult decision considering the fact that the thing is only four years old.
Thanks a million.
Before you do anything, you have to know why the temperature is low. It is not because there are bad sections of pipe. It could be a thermostat, or it could be some weird piping problem in the building. Do not waste $300.00 or $600.00 or any other amount until you know what has to be done.