A known fault with this boiler is to do with Air Pressure Sensing, either the switch itself, the associated flexible tubes, the restrictor, the venturi on the flue or the boiler cover sealing.
Quite a lot to diagnose, never mind the otehr stuff - valves, sensing, electronics etc.
As a general point, it would be helpful if the start sequence timing was known so we could put more meaningful posts on here when we get probs?
As I understand it, the sequence goes something like this
Check APS contacts are open
Start Fan - wait for normal speed
Check APS contacts close
Open pilot injector
Open pilot gas valve
Sense pilot flame
Open main gas valve
etc etc
Seems to me that as the boiler ages, fans may slow down due worn bearings, flues may get partially obstructed, air tubes and venturi may get partially gunged up (especially the pressure tube as it is inhaling flue gases?) That's why we have the boiler serviced right?
But there must be timing tolerances in the contol electroncis which make some allowances for these various components to age. If the tolerances were too tight, boilers would be locking out prematurely. If they were too slack, they could be dangerous.
Hence my comment about the timings for each part of the sequence. Any comments?
Quite a lot to diagnose, never mind the otehr stuff - valves, sensing, electronics etc.
As a general point, it would be helpful if the start sequence timing was known so we could put more meaningful posts on here when we get probs?
As I understand it, the sequence goes something like this
Check APS contacts are open
Start Fan - wait for normal speed
Check APS contacts close
Open pilot injector
Open pilot gas valve
Sense pilot flame
Open main gas valve
etc etc
Seems to me that as the boiler ages, fans may slow down due worn bearings, flues may get partially obstructed, air tubes and venturi may get partially gunged up (especially the pressure tube as it is inhaling flue gases?) That's why we have the boiler serviced right?
But there must be timing tolerances in the contol electroncis which make some allowances for these various components to age. If the tolerances were too tight, boilers would be locking out prematurely. If they were too slack, they could be dangerous.
Hence my comment about the timings for each part of the sequence. Any comments?