Potterton Puma 80 shutting off after running hot water?

[Dannyf1380]

Good Evening,

I have a bit of an annoying problem with my combi boiler,

When running hot water for a bath etc it decides to shut off the pilot light.

I suspect it is overheating as the water is scalding and shortly after it shuts off i can hear a relay click.

I've replaced the hot water switch and valve a few months ago so I don't think this is sticking (the led also goes out once the tap is shut)

The diverter valve is relatively new (about 18months) but I know these are crap?

Any ideas?

Thanks Danny.

 

[powell30]

Boiler stat? Heat exchanger scaled?

 

[Dannyf1380]

Someone said it could be the DHW temp sensor?

Could that be right?

 

[Agile]

It could well be the DHW sensor. Measure the resistance when completely cold should be around 10k.

It could also be the gas valve settings for which you should call an RGI.

But first, does the flame stop immediately when you turn off the hot tap?

Tony

 

[kevplumb]

probably scaled up

 

[Dannyf1380]

It could well be the DHW sensor. Measure the resistance when completely cold should be around 10k.

It could also be the gas valve settings for which you should call an RGI.

But first, does the flame stop immediately when you turn off the hot tap?

Tony

It stops about 5-10 secs after the tap is closed, and then a short while later a relay clicks.

The water is also very very hot.

 

[Agile]

If the flame does not shut off immediately the tap is turned off then its normally caused by the DHW demand switch.

If that is really turning off promptly then it could be a PCB or gas valve fault and would need an experiened boiler engineer.

Tony

 

[kevplumb]

It could well be the DHW sensor. Measure the resistance when completely cold should be around 10k.

It could also be the gas valve settings for which you should call an RGI.

But first, does the flame stop immediately when you turn off the hot tap?

Tony

It stops about 5-10 secs after the tap is closed, and then a short while later a relay clicks.

The water is also very very hot.

hot water flow switch sticking

common problem on these

 

[Dannyf1380]

If the hot water flow switch was sticking wouldn't the light on the PCB still be lit?

 

[kevplumb]

do you watch it when you turn the tap off

if it is sluggish returning the boiler will overheat

 

[Dannyf1380]

Could the adjustment of the switch also be the cause as the complete unit is relatively new as the last one completely seized and leaked.

On the otherhand why is the water scalding hot?

 

[Dannyf1380]

Just checked the flow switch with the mrs controlling the tap and the flow switch shuts off instantly when the tap is shut off.

What appears to be happening is that when the hot water is run for a long time (for a bath etc) the pilot goes out which I think may be due to overheating.

The hot water temperature is also scalding hot.

Could the same fault be causing the above problems? and what could it be?

 

[kevplumb]

probably scaled up

just a thought

and to be fair you didn't explain the fault very well at first

you are there we ain't fella

 

[Dannyf1380]

sorry mate what could be scaled up?

 

[kevplumb]

heat exchanger