Ok sounds about right for me. Only have one valve which is the 3 port as in the picture.I guess I will have to replace this but is it a DIY job I wonder!
That depends on what is wrong with the valve and how old it is. On modern valves the actuator - that's the metal box part - can be separated from the body and replaced on it's own. Faults can develop in either part; it's a case of finding out which. So here goes!
Turn power off. (Turning the timer to HW and CH off is
not enough).
This resets the valve to the default position.
Move the lever in the slot to the MAN end.
You should feel resistance as you are opening the valve against a spring.
If there is no resistance, the valve is stuck open.
If there is resistance, release the lever, which should move back to the Auto end.
Do this several times to check if the valve is sticking.
If the valve is sticking, you need to remove the actuator. The method varies depending on make.
If you have a Honeywell valve and the actuator does
not have a small bump on the top, the actuator cannot be removed; you will have to get the complete valve changed. That normally means a drain down.
When you have removed the actuator, you will see the valve shaft sticking out of the body. This should rotate easily (about 20 degreed only). If it is stiff, apply a little WD40 or similar light oil to the shaft to see if it frees. If not, you will have to change the complete valve.
If the valve is NOT sticking the actuator needs to be checked.
Make sure the programmer is set to CH and HW OFF and the room and cylinder thermostats are set low.
Turn the power ON
Set HW ON and turn cylinder thermostat up
The boiler should light
Check that the pipe from valve to cylinder gets warm.
Turn CH ON and turn room thermostat up (You should hear the valve move)
Boiler should continue to run
Check that pipes from valve to cylinder and radiators both get hot
Turn HW OFF (You should hear the valve move)
Boiler should go OFF and a few seconds later restart
Check that pipe to cylinder cools down and pipe to radiators warms up.
Turn HW ON
Boiler should go OFF and a few seconds later restart
Check that pipe to rads cools down and pipe to cylinder warms up.
Turn HW thermostat to minimum
Boiler should go OFF and a few seconds later restart
Check that pipe to cylinder cools down and pipe to radiators warms up.
Report findings
