Potterton Puma 80 keeps switching off

[Kazade]

Hi,

Recently our combi boiler started turning itself off randomly (the pilot light kept going out) and although we can reignite it immediately it isnt long before it goes out again. This happens when the central heating is on, and most often if we run the hot tap while the heating is on. However we can run the hot water with the heating off and the boiler works fine.

We called out an engineer and he said it was being caused by our mixer shower not allowing enough water through which was causing limescale. When he left though the boiler worked fine for a month, but now its started switching off again when the heating is on.

So I have a couple of questions:

1. Is the engineer right? I fail to see how the shower can be causing this, when it is the central heating that causes the problem. We can run the shower without the heating fine, same as the hot taps. Also, the problem reoccured this morning BEFORE the shower had been run.

2. If its not the shower, what could it be?

The pressure gauge seems fine, the red arrow is in the centre of the green area, and the black area is about a third of the way into the green.

I would be grateful for any help, I am going to call for an engineer again, but I'd like a second opinion from someone.

Thanks,

Luke.

 

[ChrisR]

Could be lots of things, or a combination

Look in boiler at the circuit board.
Turn ch off
Run a hot tap. Red light should come on, and importantly, go off as soon as tap is turned off.
If not, Flow Switch is faulty.

 

[Kazade]

Well, I did as you said, and the red light comes on when the hot tap is on, and goes off when we turn it off so that seems fine. When the central heating comes on, and the pilot light goes out, the boiler makes a lot of noise until we turn the heating off. Any other ideas?

 

[Rob]

pump could be failing. untwist black cap from front and pull forward to lock it onto the impellor shaft, it should be spinning quite violently! have a rag handy aswell.

be carefull though if boiler has be on as water could turn to steam and seriously burn.

 

[Kazade]

Thanks for your advice rob884, but im a bit worried about fiddling with it too much especially if there is risk of burning!

We just had an engineer round, he took one look at it, said the pressure needed to go up (which is rubbish it was in the green) and then left. Two minutes later it broke down again. Now we have to call British Gas again, and make another appointment. Honestly whats the point of coming if hes not gonna look into the problem past looking at a gauge?