Lukewarm HP water heater-sometimes – GreenBuildingAdvisor

Seems to me you need some real data before you make a diagnosis.

First I think it is a mistake to jump to the conclusion that the water heater is at fault.

Second I doubt the time of day is a direct factor.

Consider, code requires all new shower valves have an anti-scald function that could be malfunctioning. Not just the one you are using could be at fault and mixing hot and cold water.

Consider water will flow in the path of least resistance. If somehow the cold water can get into the hot water pipe without going thru the heater you would get a mix and lukewarm water. A leaky check valve on a hot water recirculating system could do this.

If you are still convinced it is the water heater, put a $25 data loggers probe under the insulation up against the heaters tank. And monitor the tanks temp for a month.

Is there any chance you signed up for the demand reduction billing program that lets the utility control your water heater?

https://www.amazon.com/dp/B0CX947JYZ?ref=emc_p_m_5_i_atc&th=1

Walta