When only hot water is turned on, radiators come on, sometimes not all of them and not always the same ones. The only way that I can control the heating is with the rad valves.

Eddie, May 2009

The 3 port valve has failed. Most likely it's only the actuator motor on top of the valve.

Easy job to change just the motor BUT it should be done by an engineer as this involves mains voltage connections.

Also important to get the right part as there are about 5 different valves depending on the age of your Heatslave.

bunslinger, May 2009