The UH3 is designed to work with our four channel 230v time clock (TM4) and 230v Set Back Thermostats (DS-SB) but equally could be used with any 230v room thermostat (DT-B, PRT-B, PRT and PRT-TS). Up to eight zones can be controlled from the UH3. On board the UH3 are two heating time channels, each zone allows you to specify which time channel it should follow. Two additional time channel connections are provided for hot water control or other auxiliary devices. On demand from any zone, a 230v output is provided to switch the relevant zone actuator , underfloor heating pump and valve. A volt free connection is supplied for the boiler, making it compatible with almost all types of boilers. A simple slide switch makes zone 8 suitable for controlling a radiator zone. When used for controlling radiators, zone 8 does not enable the underfloor heating pump, valve and boiler. Up to four actuators can be connected to each zone.