How about a link between L-1.
Do you mean at the LP522 programmer? Terminal 1 is the HW OFF terminal. This will get 240V internally from L when HW is set to OFF. This must be happening or the boiler would never fire for CH only.
The problem is that the boiler does not turn off when the programmer is set to OFF.
Rayger (if you are still following
)
1. What happens if the programmer is set to a CH ON period in ONCE or TIMED with the boiler running and the timed period comes to an end? Does the boiler go OFF, as it should, or does it continue running?
2. When the programmer is set to CH OFF,
(a) Measure voltage on the valve White lead (Terminal 4)
(b) Measure voltage on Grey lead (Terminal 7)?
3. Turn HW OFF at programmer; disconnect Orange wire; turn CH ON and room stat high (
boiler will not light).
(a) Measure voltage on Orange wire.
(b) Measure voltage on Terminal 6
4. Turn CH OFF at programmer
(a) Measure voltage on Orange
(b) Measure voltage on Terminal 6
Please supply results 2a, 2b, 3a, 3b, 4a and 4b.