Hi,
Boiler fires ok in h/w mode but refuses to fire in CH mode.
Thermostat looks ok - clicks when powered and moved above ambient temp. Also overriding thermostat (shorting the live to call) does not cause CH to fire.
I think that I have a faulty mid-position valve (ACL 679H340-30L0)
It is always set in the W position. Checking the live voltages offered by the wiring centre to the valve, I get....
---------------ORANGE GREY WHITE
ALL OFF -------> NO YES NO
H/W ONLY-----> YES NO YES
CH ONLY -----> NO YES YES
BOTH -------> YES NO YES
But... the last one puzzles me - why would BOTH be the same as H/W only.
Any ideas ?
Thanks
Deag
Boiler fires ok in h/w mode but refuses to fire in CH mode.
Thermostat looks ok - clicks when powered and moved above ambient temp. Also overriding thermostat (shorting the live to call) does not cause CH to fire.
I think that I have a faulty mid-position valve (ACL 679H340-30L0)
It is always set in the W position. Checking the live voltages offered by the wiring centre to the valve, I get....
---------------ORANGE GREY WHITE
ALL OFF -------> NO YES NO
H/W ONLY-----> YES NO YES
CH ONLY -----> NO YES YES
BOTH -------> YES NO YES
But... the last one puzzles me - why would BOTH be the same as H/W only.
Any ideas ?
Thanks
Deag