CH Help please

[nav1881]

I have a Saunier Duval XEON 30HE Condensing boiler Open vent system.

OSO unvented tank.


The water works fine but the heating only works if hot water is also ON at the same time.

On the Heating side when I bleed the RADs water come out but lots of air in all RADS. I have bleed all Rads for HRS on end but can't get rid of the air in the system.



PLEASE CAN ANYONE HELP WHAT COULD BE THE PROBLE

 

[TheGasMan26]

Most likely you have an S-Plan system(2xZone valves), the zone valve for ch has likely got a failed motor, very easy to change and about £12, to test simply turn the CH on and stat up then rush to ch zone valve and observe with cover removed to see if it actuates, if not you likely have a failed synchron motor.

Though there is a possibility the valve spindle could be siezed(remove head, apply wd-40 to spindle, free up by rotating gently with grips, then apply proper lubricating oil, replace head & test)

Or, if the motor is actually motoring over, the switch inside the actuator head(box on zone valve) could be faulty. Now depending on the brand, Honeywell, Drayton, etc. the head may be replaceable, if not your talking full valve(brass body & actuator head)

Good luck.

 

[nav1881]

Thanks for your reply!!

I have a Honeywell and will try that.

Could that be the problem of the air in the system?? On CH Side