A homeowner who upgraded to a heat pump water heater was looking forward to an efficient, lower-cost source of hot water. Instead, their AO Smith unit has been intermittently cutting out, leading to unexpected cool showers.

Heat pump water heaters can save many households on electricity.

What's happening?

After a recent installation, the homeowner said an AO Smith HPV10-66H01DV bought at the end of 2024 has been shutting off randomly. In a post on Reddit, they said the appliance itself was not displaying an error code.

The issue appears to be a tripped in-line GFCI on the power cord, which must be reset before hot water service returns. "Since it's been installed, we'll find we have occasional cool showers," the original poster wrote.

They also wrote: "No error codes on the unit itself. And then it's fine until it happens again a few days later." In trying to diagnose it, the homeowner said their dad, a retired electrician, suspected the electric panel's lack of a ground rod might be contributing, so one was added.

Although that seemed to solve the problem at first, the shutdowns returned. That leaves it unclear whether the nuisance tripping is tied to the outlet, the GFCI device, the circuit setup, or the heater itself.

One user on Reddit shared how they also had their water heater's power trip and shut off sporadically, but they "figured out it was in the rare event that the electric resistance element fired up. Turns out when it ran in heat pump mode it was fine, but the added load of the element tripped the breaker." They added that the "installer simply made a mistake and did not do a 240v. Fixed and runs great."

Why does it matter?

Heat pump water heaters are among the most attractive home electrification upgrades because they use far less electricity than conventional electric water heaters while still providing the same everyday service: hot showers, clean dishes, and laundry. 

They can also help reduce planet-warming pollution from the home — one study found that replacing traditional HVAC systems with heat pumps can reduce a household's average energy pollution by at least 36%, and on the high end 64%.

Installation details can affect performance.

If a high-efficiency appliance keeps shutting off, homeowners lose the comfort they paid for and may also miss out on the savings that made the upgrade appealing in the first place.

Repeated GFCI trips can point to a wiring issue, moisture problem, faulty protection device, or equipment defect that should get a closer look.

What can I do?

If a heat pump water heater keeps tripping off, a good first step is to document exactly when it happens: after showers, during high humidity, overnight, or at random. Homeowners can then share that record with the installer, manufacturer, or a licensed electrician to help narrow down whether the issue lies with the outlet, GFCI, circuit, or unit.

Companies such as Cala are also working to make heat pump water heaters easier to live with. Its customizable smart heat pump water heaters help homeowners decrease their energy bills by heating water exactly when it's needed. 

By learning a household's usage patterns, Cala's systems are designed to reduce waste while still keeping hot water ready for showers, laundry, and dishes. For shoppers who want more control over timing and savings, Cala represents a growing push toward smarter electrification at home.

The underlying cause still has not been identified. As the homeowner put it, "The troubleshooting section of the manual doesn't address anything like this and there are no error codes to reference, so we're not sure what to check/try next." And despite the ground-rod attempt, they were still dealing with "a very not hot shower this morning."

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