Potterton PUMA 80 - pilot keeps cutting out when C.H. on

[tomcubi]

I hope you can help with a few tips. I wouldn't like to replace this Potterton PUMA 80 which is probably 10 years old, as we'll have to renew the whole system in 6 months, but the pilot keeps cutting out.
It happens when the central heating turns on. Today I ran the hot water several times and the pilot never cut out, but suddenly this evening some steam started to come out from the air vent 5 mins after the central heating turned on.
I'd be very grateful for any advice you can give me on this.

 

[kevplumb]

get an RGI in

 

[penfold46]

Bleedin Nora, how many old threads did you pull up?!

www.diynot.com/forums/viewtopic.php?t=67438
www.diynot.com/forums/viewtopic.php?t=15470
www.diynot.com/forums/viewtopic.php?t=6626
www.diynot.com/forums/viewtopic.php?t=236599

Anyway, could be the wax capsule in the divertor valve.

P46

 

[tomcubi]

Thanks Penfold46, I previously read all the posts you sent me but this problem seems to be a different one. Also in the posts you sent me the real problem is not mentioned in the end therefore I am still very unsure.
I had a Gas Safe Registered to have a look at it and replaced the thermal couple and the HW overheat thermostat... £90 for no reasons at all.

Thanks for your help or any help you come up with.

 

[tomcubi]

I changed the wax capsule, but hasn't made any difference: as soon as I turn the CH on, after 1 min, the boiler cuts out.
Hot water runs ok.
Either faulty pump or central heating sensor causing boiler to go to high limit and cut out pilot? Or I should have replaced the whole diverter valve.
I tried to see if the pump vibrates, but I'm not sure, the whole boiler vibrates..by the way the hot water is working ok, therefore the pump must work ok.
Thanks in advance for any more tips.

 

[adlplumbing]

get rgi in something is wrong and can`t realy say as i am not infront of the boiler

 

[bengasman]

Steam coming out anywhere is bad. You need a pro as it is well possible that the safety is not working.

 

[mysteryman]

Something is obstructing the central heating side of things [why do you want CH in August anyway?].

Check that your CH isolation valves are both open!

Have you got thermostatic radiator valves on all rads? If so, is there a bypass?

 

[tomcubi]

I appreciate I need a RGI to check this boiler out, but do you know anyone who's honest and who's not charging £90 to replace, in 1 hour, a thermal couple and a DHW overheat sensor (£11 for both parts)? Above all when they were still working absolutely ok?
I haven't found any RGI I could fully trust in 10 years in the building industry.
Area TW18.
Thanks anyway for your replies.

 

[mysteryman]

Try Alex Macfarlane, somewhere in SW8/9 postcode area. Nice, bright lad.

 

[tomcubi]

I'd like to solve the problem before the autumn comes.
Not only, but the people who are living in that house need the central heating in some cold mornings...
Almost in all the radiators there are the thermostatic valves. I guess the water inside the radiator is quite dirty as no one flushed the system in the last 5 years.
The CH valves are both fully open. Thanks.
I thought it could have been some scale, but in June the system was working ok and in less then 2 months totally blocked?
The flow pipe doesn't even become luke warm.
Today as I said I replaced the wax capsule, maybe I should have replaced the whole diverter valve? Maybe I didn't put the wax capsule properly? It seemed to be a simple job.. A parte from the mess draining the boiler as the relief valve doesn't open properly.

 

[bengasman]

You could contact Agile, he may cover that area.
Personally, I don't find £90 for the call out, plus an hour's work, plus £22 in parts excessive. The fact that he misdiagnosed the problem is worse.

 

[steve32]

when you turn on a hot tap the diverter valve shuts to allow all heat to go to heat HW when hot tap is turned off pump carries on running if hot water is approx 80 diverter will open to dump surplus heat.
The way we test diverter is turn heating off, turn on hot tap run approx 2 galls hot water, tap on slow so boiler fires and gets to max heat, turn off tap pump on combi runs, when wax head on diverter reaches approx 80deg approx 1 min hot flow to heating should get hot (if you hold pipe be careful it will get very hot very quick) if pipe gets hot diverter is working if not then combi will overheat and go to lock out.
if diverter is ok i would then suspect pump


hope this helps steve

 

[tomcubi]

Thanks misteryman, although SW8 is not that close, mainly because of the traffic.
Bengasman, this is what I am saying, £90 without solving the problem is not acceptable. The parts were £11 (including VAT).
If he had solved the problem, no worries and all happy.
Thanks for indicating Agile. I'll see if he's available.
TW18 is Staines, close to Heathrow.

 

[tomcubi]

Thanks Steve, that's interesting.
I think that I should have changed the whole diverter valve, not only the wax capsule, as from what you are saying the diverter is not working properly. In fact I ran more than 4 galls of HW with the heating turned off, but the diverter was still cold. I'll try again with tap on slow to get to max heat, as you say.
Thanks again.