Combi boiler CH problem

[Familyman]

Hi
I have a problem every time I switch on the CH (Timed or constant).
It fires up for about 30 secs and then cuts out. After a short period of time it does the same thing..fires up for about 30 secs and then cuts out. This continues for approx 20 mins where it will finally stay on continuously till the radiators get hot. There is no external thermostat connected.

Any Ideas?

 

[ChrisR]

Boiler is....?

 

[Familyman]

Boiler is a Potterton Puma 80.

 

[gazthepottertonengineer]

i bet its a puma and its got dripping hot tap syndrome

My crystal ball is very clear today

 

[gazthepottertonengineer]

told you i did actually type that before i read that post spooky hey

 

[gazthepottertonengineer]

check your taps mate i bet one of the hot taps needs re- washering

 

[Familyman]

Thanks
I've had a look round and can't see any evidence of taps dripping/leaking...even those that feed the washing m/c, although turning taps on does jump start the boiler even when they are turned off again ..although the cycle just starts over.

 

[gazthepottertonengineer]

sounds like your wax capsule needs replacing then not the easiest job in the world even for a potterton engineer like myself

 

[meldrew's_mate]

Gaz, are these wax-stats available seperately, last time I tried I had to buy the whole diverter valve?

 

[gazthepottertonengineer]

yes you do have to buy whole diverter
where abouts in bucks are you

 

[Familyman]

Thanks Guys

Much appreciated!

 

[ChrisR]

Yes you can just buy the wax capsule. I'll send you one for about £25 inc post.


Not that it'll solve your problem, which is that your hot water flow switch is sticking on. Have a butchers at the pcb and you'll see there's a red light on even with the tap off, which there shouldn't be.

 

[gazthepottertonengineer]

sorry chris i cant see how this is the problm if the heat isnt getting to the rads sorry but your wrong mate definate wax capsule needed if there are no dripping taps

 

[Agile]

As usual we dont get a very clear picture of whats happening but he did say:-

"""This continues for approx 20 mins when it will finally stay on continuously till the radiators get hot"""

I think that we must assume that the radiators ARE getting hot as he says!

This would make me deduce that the wax stat IS working BUT its doing so VERY sluggishly and needs 20 minutes without DHW use to get it to move enough to get the CH working.

The ChrisR solution to test that is to play his blowlamp on the front of the diverter for a few seconds to really heat it up.

Tony Glazier

 

[ChrisR]

Gaz you're right I'm answering the wrong post again. When I read it last it said something different. Didn't it?? Not sure whether to start taking the other tablets again or stop these purple ones.