Potterton Puma 100e CH Problems

[Jezzza]

I have a problem with my boiler. HW is fine but when it comes to the CH the boiler fires up, Pump runs (which has been replaced) and everything looks ok for about 45-60 seconds. Then the flames die down in the boiler. The lockout light does not illuminate. The room thermostat is calling for heat.

I have checked the CH temp sensor and its around 13 - 14 Kohms which is the same as DHW. When I checked the C.H. Limit Thermostat there was no resistance at all when cold. I would of thought there should be some resistance? Any ideas would be great before I order a new limit theromosat and waste 40 quid!!

 

[Slugbabydotcom]

Limit stats [also ignition pcb's and diverter valves] are notorious on them, but my 'great idea' 4 what its worth is to check that you opened the valves to the flow and return after you fitted the pump

 

[gazthepottertonengineer]

check your hot taps sounds like dripping hot tap syndrome if any are dripping sort them if it still plays up replace wax capsule in diverter valve

 

[Jezzza]

There is a dripping tap in the kitchen, it's only very,very slight, Would this effect it? Thanks for the help.

 

[Agile]

Yes it will!

If all the valves are open then its the diverter valve. The boiler might even come on for CH after 20 minutes with no HW demand.

Fix the tap and then see if the boiler needs fixing, if so its the diverter!

Tony

 

[ChrisR]

When I checked the C.H. Limit Thermostat there was no resistance at all when cold.

That's correct - it opens when hot!

Shut the cw input off at the boiler to stop your tap dripping
In this case I don't think it will be the drip causing the problem. If that amount of water flow were cooling the relevant bit of boiler, the CH wouldn't come on at all. That's right isn't it chaps? So the waxstat or DV itself are suspects.

 

[Agile]

Chris, I think he means that the boiler fires up for a few seconds to warm itself up!

The rads stay cold because the diverter is held in the DHW position.

As the diverter ages only the smallest of HW leak will stop it ever reaching the CH position.

Tony

 

[Jezzza]

Thanks for your input folks, Ill fix the tap leak and if I need to i will fixor replace the diverter.. I will let you know the outcome.

 

[Jezzza]

Changed the wax head on the diverter valve today and the rads are working nicley. Thanks for the help folks.

 

[gazthepottertonengineer]

Our pleasure mate glad to hear you got it sorted