Hi Albert,

Look for "frost protection". A friend has a pipe heating loop between his house and well in Sweden. I believe the thermostat was small and adjustable but it would close (not open) when the temp goes below a certain level. He told me they are set 'by experience'. People out there know how low temps can get below freezing before this electric heater line has to come on for a buried line.

Regards, Joerg

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