Vokera Excel SP80 - Boiler Intermittant Firing up

Hi, I have had the above boiler for around 8 years now, but have been having problems lately. Unfortunately, the boiler hasn't been serviced in that time.

Firstly, the shower (bath shower mixer tap) has a tendency to run hot-cold-hot-cold.

Also today, there was no hot water, or heating. When I switched the boiler to constant, it didn't fire up, though the pilot was on, and stayed lit at all times.

I thought it may have been a blocked covered flue (dad told me it may be this, as he had similar problem at his home), so checked out back, and cut-back some nearby ivy. The Boiler fired up. I thought this must have been the problem. But when I switched the boiler off, and back on, it didn't fire again. After trying this a few times, i managed to get it fired again, but it is now fairly intermittant.

Would never fire up each time I tried.

I know these things can be a bit vague, but would rather have an idea before calling an engineer, who may try a few things before finding the fault, and thus, cost unnecessary money.

Cheers for any advice/info offered.

MJ

Update: The heating is working, so it is just hot water that is the problem.

Tried to run the bath this evening, and even at a trickle, it only stayed hot for about 3 minutes before going cold.

I went down to check the combi, and it fired up again, the temp guage rose to about 65 degrees, then it cut off again.

Just doesn't want to stay on constant.

MJ

Diaphragm in the diverter valve needs replacing.

Changed the diaphragm today ,however the old one wasn't perished, or even worn...looked almost as new as the one I put in!!

It appears the heating is playing up also.

Sequence of events...

Switch heating/water on...

Pump starts up...

Fan is working...

no hot water/heating.

then, miraculously, the boiler will fire up....

one to two minutes later, it shuts off again...cold water again.

Today we have replaced the diaphragm, and also cleaned out the flue. There was't much in it, just some fluff, and dust, but dad (who has had problems with his own Boiler in past) said that could be a problem.

Neither of these 'remedies' has helped.

We have gone through the step-by-step fault finder in the back of the manual, but theres nothing conclusive. It points to either a flow switch, or the PCB. But to fathom the problem, some points on the PCB need testing.

Think I am going to have to get a pro to take a look at it.

MJ

MJ said:

and also cleaned out the flue. There wasn't much in it, just some fluff, and dust,

Click to expand...

Unless your Corgi reg., you really shouldn't be touching the flue or anything related to gas supply and combustion. You could inadvertently do something dangerous.

As you are in Newcastle OT, isn't that within driving distance of Hartlepool? Kev might be able to get to you?

Tony