I've got a Honeywell diverter valve next to the hot water cylinder, it is a three position valve. (hot water, central heating and both) The problem I am having is that it sticks in the 'both' position, so even after the cylinder stat is satisfied it continues to heat the domestic hot water too hot.
I've removed the motor head from the valve body (two screws) and I can easily turn the valve shaft between finger and thumb, also the actuator seems to work OK when it's not coupled to the valve. It seems that the thing relies on a spring for movement in one direction.
The only think I can think of is to spray WD40 up it, but it's not made any difference. Are then any 'tricks of the trade' to persuade these fickle things to work as they should?
Cheers Julian.