Rheem Hybrid Water Heater Exhaust Temperature

A homeowner posted a question in an online building forum about their 65-gallon Rheem hybrid water heater. This type of unit uses a heat pump to pull warmth from surrounding air to heat water, rather than relying only on an electric heating element, which normally saves energy. The owner noticed the unit, now about five years old, has started running constantly in heat pump mode without properly cooling the exhaust air. The exhaust was only a few degrees cooler than the air going in (69 degrees out versus 72 degrees in), when it used to run much cooler. At the same time, daily electricity use jumped from 3-4 kilowatt-hours to 9-13 kilowatt-hours, even after the owner cleaned the unit's filter.

No one had answered the post with an explanation or fix at the time it was shared, so there isn't a confirmed cause or solution to report. If you own a similar hybrid water heater, this is worth keeping in mind: a heat pump water heater that suddenly starts running longer while barely cooling the air around it, paired with a sharp rise in electricity use, is a sign something may be wrong with the heat pump portion of the system rather than normal wear. Since the unit reviewed here is five years old, it's a reminder that even efficient equipment can develop problems that quietly erase the energy savings it was bought for, so unusual jumps in your own utility bills are worth noticing.