I have a room in my apartment that can sometimes get around 40°F (4°C), and that's where my new tankless water heater is stored. Should I take any special precautions to keep my pipes from freezing or to avoid any other weird problems with my water heater? I live in the US Midwest in a second-floor apartment.

Other details from the comments:

  • Model: Rheem RTEX-24
  • The room is on an exterior wall, some of the plumbing goes through an exterior wall, and the water heater is about 3 feet from an exterior wall.
  • This strongly borders on HomeImprovement.SE topics.
    – Erik
    Commented Sep 9, 2020 at 6:48
  • 2
    How would water freeze at "plus 4 degrees Celsius"?
    – sharptooth
    Commented Sep 17, 2020 at 10:33
  • @sharptooth Good question. I am not a scientist/engineer, but I was thinking maybe the water in the pipes could be cooled by water outside the room.
    – capet
    Commented Sep 17, 2020 at 13:48
  • 2
    Yes, that's possible but if that water freezes then all adjacent pipes are also at risk.
    – sharptooth
    Commented Sep 17, 2020 at 15:22

1 Answer 1


Since the water heater is not on an exterior wall, it is likely that the pipes you mention which do pass through the exterior wall would freeze before pipes inside the heater do. This would cause damage, of course, but might spare the heater.

Addressing the issue with pipes freezing, there's an interesting discussion over on HomeImprovement.SE: "What is the minimum temperature for house heating system to keep pipes from freezing?".

To monitor the pipes for freezing, there are a number of commercially available alarms -- some stand-alone, and some sold as part of alarm systems. There's also plans on Instructables to build one yourself with an Arduino.

  • Thanks!!!!!!!!!
    – capet
    Commented Feb 1, 2021 at 3:41

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