The Honeywell HCS80 Extension module works together with the HCC80R underfloor heating controller to add a further 3 underfloor heating zones to an evohome multi-zoned system.

The underfloor heating controller can control up to 5 zones of and can be expanded by using this optional HCS80 extension module to control a further 3 zones. You can also use a combination of underfloor heating controllers and extension to control up to the a maximum of 12 zones allowed by the evohome system.