powermax 155 - HW ok but no CH

[helishaker]

The fault has now progressed - when the selector switch is set to select HW & CH the boiler doesn't fire at all (it was previously doing the HW). With the selector switch set to HW only, the boiler fires up OK and HW is supplied. Does this suggest that the problem is elsewhere other than the cold start stat ???????????

 

[gazthepottertonengineer]

not very common but could be the switch faulty

 

[helishaker]

Thanks for the suggestion but I must ask if there is a possibility of the programmer being at fault. My reason for suspecting the programmer is the way the fault has developed - the green neon HW and HW+CH switch was in the HW+CH position when a buzz from the programmer was noticed and the CH failed, then the subsequent failure of the HW while the HW+CH switch remained in the CH+HW position. With the switch in the HW position the boiler fires up & hot water is available.

If it is the programmer or switch (or whatever) is there a way of bypassing the electronics and running the CH pump as a temporary measure to get the heating running - we just need to get some heat to thaw out the eskimo who moved in !!!!

 

[gazthepottertonengineer]

yes you could connect the pump live and neutral to the permanent live and it would work but i cant recomend it as it would be modifying the appliance

your right as well does sound like programmer as when switch is in constant hot water mode it doesnt look at programmer for hot water demand so you could be right

 

[helishaker]

With the pump is connected directly to the main supply the pump works and the boiler functions. I think the programmer must be the culprit!

 

[ncd]

With the pump is connected directly to the main supply the pump works and the boiler functions. I think the programmer must be the culprit!

Did you get to the bottom of this? I've a very similar, perhaps identical set of symptoms! My diagnosis so far is it's programmer/timer on the grounds that there is no power being sent to the thermostat so it can't 'call' for heat.

Any helpful hints gratefully received! Thanks.

 

[Agile]

A useful hint is that posting was made two years ago!

 

[ncd]

A useful hint is that posting was made two years ago!

Fair comment! But I'm still none the wiser what the actual solution was