heating only comes on when hot water is also selected

[dehorne]

Boiler type is an ideal classic. In order to get the heating to come on I also have to select hot water on the timer. If tank is full I have to drain some down to get it to fire. This happens occasionally, but seems to be getting more frequent - any ideas?

 

[namsag]

Geuss you have 2 two port motorised valves, your heating one has seized in the partially open position allowing heated water to pass when HW selected.
May need whole valve may just be the motor jammed up and need replacing

 

[dehorne]

many thanks, but not quite right. Heating will only come on if selected on the timer. Only issue is that water also has to be selected ie. just hot water select then no heating, to get heating have to select both

 

[namsag]

If it 2 valves then heating valve has worn and motor is not taking the cam over far enough to hit the microswitch to bring on the boiler

 

[dehorne]

Got you, looks like I'm changing a valve then. Thanks for the help

 

[dehorne]

Just looked again, to check parts required. I have a single 3-port valve, is it still likely to be the same problem

 

[namsag]

Would still say not making switch in 3 port or faulty switch. you may get away with fitting just a new valve head depending on what age and make

 

[dehorne]

many thanks will change the valve then.