: My on demand water heater is not heating as well as it used to (installed 1990) I have considered that the ambient temp has been cooler than normal. But I wondered if there is an output temp controlling part that may be failing? calcified? or?It may be that the ambient temp is low, these units usually raise the temperature approx 50 C above ambient ……… at the base of the heater there is a nob that will alter the water flow through the unit ……. try altering this ie. less water more heat, more water less heat. Also it may be that you need a new diaphram in the water valve, this can reduce the height that the main gas valve opens to the main burners, you may not be getting enough gas so have it checked by a qualified service company……..manufacturer usually recommends a service at intervals not exceeding 12 months……. good luck.
