Is there a 120 Volt switch that would shut down power to a dehumidifier when the outside temperature goes down to 35°F to protect the drain line from freezing. A digital thermometer would need to be mounted outside to detect the 35°F temperature to shut down power to the unit.

I install dehumidification systems to control interior environments after our mold remediation projects but here in the northeastern USA, the temperature freezes the drain lines and the units no longer have a self draining operation.

  • You actually risk not only the line freezing, but the whole unit icing up. My whole unit will ice up in my basement, which never gets cold enough for the line to freeze.
    – Joe
    Oct 17, 2012 at 1:43

2 Answers 2


You can wrap the drain line in electric pipe heating tape to prevent it from freezing:

Pipe Heat Tape

You should be able to find it at your local home improvement store.


There are any number of specialty products that can perform the function of a temperature switch. A thermostat is just one type of example. You can also search for a "freeze switch".

Here is an example of a timer / thermostat type product that could be adapted from its normal swimming pool usage model.

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