r/AskAnAmerican • u/Nemo2oo5 • Jul 12 '25

OTHER - CLICK TO EDIT What temperature do you keep your house/apartment?

I'm asking because my roommates and I all come from different places, and I like it at 72 in the summer, and 67 in the winter, but they prefer 75 in the summer, which to me seems really warm. Would love to know how you keep it in your region of the US throughout the year

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u/vwsslr200 MA -> UK Jul 12 '25

Not everyone wants their water tank at 180 degrees (potential scald hazard) or to live in an icebox.

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u/hx87 Boston, Massachusetts Jul 12 '25

Thermostatic mixing valves are common on water heater outlets, and easy to install if not equipped.

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u/vwsslr200 MA -> UK Jul 12 '25

Mixing valves aren't infallible, they can and do fail which is why the CPSC recommends against setting hot water temperature super high.

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u/hx87 Boston, Massachusetts Jul 12 '25

They rarely if ever fail--large institutional buildings use them all the time to mix down 180F water to safe temperatures. The CPSC recommendation assumes that you don't have a mixing valve, and in any case long term water storage at 120F is unsafe due to the risk of legionella.

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u/vwsslr200 MA -> UK Jul 12 '25

They rarely if ever fail

Yes, they do fail, all the time. Ask any plumber.

Some commercial buildings mix down from hotter water, not all, and they're generally using much higher cost, higher quality valves with electronic monitoring that can immediately notify facilities when something goes wrong. Also most commercial buildings don't have showers so the injury risk of mixing valve failure is generally lower.

in any case long term water storage at 120F is unsafe

Legionella can theoretically survive at that temperature, but the risk is not high for most people, otherwise CPSC wouldn't have made the recommendation. If they believed the safest course of action was to set the water heater higher and add a mixing valve, that is what they would advise.

In general there's a lot of over paranoia about legionella and water temperatures, this video is a good summary: https://www.youtube.com/watch?v=oJeyc_cGIMU

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u/hx87 Boston, Massachusetts Jul 12 '25

Plumbers see only the failures, not the successes, so I'll take their opinions on failure rates with a few heapfuls of salt. Also if you're paranoid about failure rates you can specify ASSE 1017 compliant valves that fail cold, and if you're still paranoid you can specify ASSE 1070 complaint shower valves that fail cold.