Wordester Greenstart 21i junior never shut off

[alcalme]

Hi, The boiler is constantly on, the timer seems to work ( as far as l know) and the receptor has the green light on. How can l diagnose it?

Cheers

 

[jackthom]

What make of timer is it and do you also have a room thermostat?

 

[alcalme]

it's a mechanical timer worcester brand, l can't find any other detail. No l don't use room thermostat. cheers

 

[jackthom]

OK is the problem that when the timer says the boiler should be OFF it's continuing to fire ?

 

[alcalme]

Yes, that's right. I also removed the timer receptor that is attached at the front of the boiler and after removing it the boiler still on. The hot water from tap is working fine as well. I also dismantled the timer and sounds like it's working.

 

[Tipper]

Does your system include one or more motorised valves?

If so then it maybe a faulty motorhead incorrectly switching a live supply to the boiler/pump and hence your boiler is permanently on.

You need to check if this is happening with a multimeter or similar and if it is then replace the motorhead of the faulty valve. Normally no need to change the whole valve, just the motorhead.

 

[ALCPlumbing]

More likely to be the MT10 mechanical timer. They break all the time. If removed the boiler will be on constantly. The timer must be stuck internally in the on position.

 

[alcalme]

l was wondering if there is any videos doing the checking with the multimeter, because l'm not sure how to do it.

 

[alcalme]

about the meter only saying that its ticking all the time and also when l try to change the temperature from the timer display ( which has day and night option) temperature doesn't change either.

 

[gigz]

For a quick fix turn the boiler thermostat right down, this should stop it firing. It won't affect the hot water performance on this boiler model.