A landlord thought a simple flush and a lower thermostat setting had solved a tenant's dangerously hot-water complaint, only for the water to turn scalding again.

Here's what to know

The landlord took the situation to Reddit's r/AskAPlumber community to see what they needed to do to fix the issue.

In the Reddit post, the landlord wrote, "Tenant called up complaining about the water temp. It was 140, waaaay too high. I shut off the heater, flushed it, turned it back on and set it to low. They tested it six hours later and said the temp was good. Next day they called and said it was back to scalding… [What would] cause the water temp to spike that high?"

Beyond the heater itself, the landlord wondered about two other variables: pipes running under the house during a stretch of very hot weather and a pressure-reducing valve installed without an expansion tank. 

Most replies, however, pointed back to the water heater's own controls and safety hardware.

After the original poster clarified that the unit was gas, one commenter gave simple advice, writing, "Gas water heater? Call a licensed plumber." 

In a separate reply, another user asked, "Is the blowoff opening?" — referring to the pressure-relief valve that is meant to help prevent unsafe buildup of heat and pressure.

More background

A water heater that keeps overshooting its setting can quickly become a health and liability issue. Repeated spikes suggest more than a minor inconvenience, especially when an earlier fix worked only temporarily.

Water this hot can cause burns quickly, especially for children, older adults, and anyone with limited mobility. Even a water heater that seems to behave normally for a few hours can still pose a serious risk if the problem returns.

The landlord also said they were hoping to avoid replacing a Bradford White heater that is only about five years old. But continued overheating can also mean higher energy use, higher bills, and greater danger at the tap.

What can be done?

If replacement is on the table, a heat pump water heater can make that decision easier financially. It uses far less energy than conventional models, which can translate into meaningful annual savings while reducing wasted electricity or gas.

Companies such as Cala are also working to modernize that upgrade. Its customizable smart heat pump water heaters help homeowners decrease their energy bills by heating water exactly when it's needed. That can reduce wasted energy while still giving households hot water when they need it most. For people replacing an unreliable tank, Cala points to a future where efficiency and comfort work together.

Where can I learn more?

Scalding water is the kind of home problem that can turn expensive and dangerous fast. These articles explore that same mix of safety, maintenance, and utility costs, from water-heater upgrades to hidden leaks and heating habits that can create friction between landlords and tenants.

• Another renter said a landlord's absurd irrigation demand pushed a painful water bill even higher.

• One realtor's blue-dye toilet test helped homeowners spot silent leaks before bills spiked.

• Households learned a popular home heating hack could quietly waste both money and energy.

A single hot-water complaint can end up pointing to a bigger issue with efficiency, maintenance, or safety. Reading through examples like these can make it easier to weigh a repair against replacing an aging unit altogether.

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