How to fit large areas of underfloor heating | contactor

Underfloor heating thermostats have a limit to the amount of power they can switch - most have a limit of 16amp.

This has an implication for larger areas of underfloor heating.

16amps is 3600watts and therefore choosing different heating mat wattages will alter the amount of heating you can install onto 1 thermostat.

For a 100watt per meter heating mat you could install up to 36m2 onto 1 thermostat

For a 150watt per meter heating mat you could install up to 24m2 onto 1 thermostat

For a 200watt per meter heating mat you could install up to 18m2 onto 1 thermostat

For areas above these sizes then you have two options.

1.Split the area into 2 zones

2.Install a contactor. A contactor is a switch capable of switching high loads. your thermostat would switch this on rather than the heating. All the heating power supplies run back to the contactor position.