potterton puma combi boiler fault

[colin_]

Occasionally when you have been running the hot water and turn the tap off. You will hear the pipes rattle in the loft and then nothing, on inspection of the boiler the pilot light will be out and the pressure valve would have been activated and because of this some pressure loss. After relighting the pilot light and topping up the pressure the boiler works fine for a short period of time
Also sometimes instead of blowing the pilot light out and activating the pressure valve it will turn the central heating on full tilt for about 20 mins and then goes back to normal. Can anybody please give me any ideas as to the fault.

 

[ratonnastick]

check the expansion vessel it might be duff search posts for potterton 155x

 

[DP]

I fail to see why the PV should be faulty. I have yet to encounter pilot outage due to PV being non operational.

The boiler rumbles, pilot goes out, boiler loses pressure- what does that suggest? BOILER OVERHEATING.

 

[ratonnastick]

think about it, duff expansion: boiler lights,water expands, pressure rises (no where to go), pressure relief goes,boiler overheat ,pilot interrupt, lock out, system pressure now low last bit of post is odd though any ideas ?

 

[ChrisR]

Your Domestic Hot Water flow switch is sticking. Standard fault on a Puma/combi80.
Its left of centre, roundish with a microswitch on the end of a stalky hex poking right. Either strip it down and clean the glass rod inside or get a new one. I keep them in stock. oakwoodATblueyonder.co.uk use the @ symbol.
I have explained what happens more than once on this forum!!