Turned off the power to the timer
Front lever on the actuator moved from the wide end of the slot to the narrow end
Side lever is towards W
Did the test – Stiff resistance on front lever when moved and noise when it moved back to narrow end
When moving the front lever from the narrow end, the side lever moved to the midway point between W&H and as the front lever moved back to the narrow end, the side lever moved back to W
Good so far
The boiler then fired! Shouldn't do that! Where's the power coming from?
Turned power back on to the timer
The boiler switched off! Why?
Both timers are set to off
No movement from either lever
Pressed HW override
Boiler lights – Slight delay approximately 1 minute
Shouldn't be any delay
Neither lever moves
Cancelled HW override
Neither lever moves
All Correct
Boiler stays on for a while then goes off Why is it going off? Boiler controlled by HW thermostat. Could be faulty. Have you checked it is wired up correctly?
Pressed CH override
Front lever moves to the wide end of the slot
Side lever moves to H
Boiler lights – Shortly after lever movements are finished
That's correct - there will be a delay as the circuit is not completed until valve has moved over
Cancelled CH override
Neither lever moves
Correct
Boiler stays on for a while then turns off Boiler should go off immediately
Power is now on but timers set to off
After about 10 minutes or so, boiler lights
Front lever is still towards wide end of slot
Side lever is still towards H
Boiler goes off after about 15 seconds
After another 15 mins boiler fires again
Front lever is still towards wide end of slot
Side lever is still towards H
Boiler goes off after about 15 seconds
So the valve is staying in the CH position (wide end) which is to be expected. But it is getting voltage from somewhere. Check voltage on orange wire
To test out a theory I reversed the override sequence this time ending on the HW, so at the end, the front lever is towards the narrow end of the slot and the side lever is towards the W
Power is now on but timers set to off There will be 240v on HW OFF
Again after about 10 minutes or so boiler lights
The front lever is towards the narrow end of the slot
The side lever is towards the W
Boiler goes off after about 15 seconds
Another 15 minutes or so the boiler fires again
The front lever is towards the narrow end of the slot
The side lever is towards the W
Boiler goes off after about 15 seconds
Based on this experiment it seems that whatever system last asked for heat is the one that continues to do so when the timers are off!
So where is the boiler getting its power from?
There are only two sources: (1) the cylinder; (2) the valve orange wire.
You should run the tests I gave earlier to find out which it is.
