Potterton Netaheat 10-16 MK2F problem

[leew]

Hi there, new here 1st post.
My boiler has decided to pack up for the first time in over 15 years, before I start I'll fully aware of dangers of working with this type of boiler hence will be calling a Corgi engineer in due course. However as like any other DIY'er I am keen to know roughly where my problem is before being potentially fobbed off with £££'s signs flying in my direction.

I have made a quick visual diagnostic and this is what happens:

1. Timer unit switched on and calls for heat/water
2. A loud click from the relay I presume and the fan starts as usual.
3. Shortly after another click from somewhere and I can clearly here the ignition module doing its business (continuous clicking) and I can see the spark being generated through the little window.
4. Then no flames whatsoever can see nothing through the window apart from the spark being generated continuously.

I suspect the Gas Valve not opening, anything else could be faulty?

many thanks

 

[giblets]

Could be either gas valve or circuit board. Voltages need to be checked to confirm which.

 

[leew]

Thanks for the quick reply, will get my multimeter on it now.

 

[Breesey]

If the pilot injector is blocked you won't get very far. Before condemning the gas valve confirm injector is clear. Spark is being generated but it isn't igniting anything.
Quite possible in a neglected/old boiler. When was it last serviced?

 

[leew]

Just checked out that the PCB should be fine, I get correct voltages from the gas valve terminals when switched on. So must be the gas valve or injector then as mentioned. The service was only done a few months ago from a southern electric gas engineer, from what I'd remembered the engineer just did a few basic checks he did'nt open it up to check anything inside the casing though. Being such an old boiler I'm just hoping there will still be parts available. Anyone know what sort of price I will be looking at for the parts / labour?

 

[Agile]

No engineer would be considered to have serviced one of those without opening the case! How else could he visually check the case seals?

Are you sure it was not meant to be just a safety check???

I would expect it to be a blocked pilot injector. That would have been checked and cleaned on a proper service.

I would recommend you complain to SE that the service was not completed properly and that it has failed as a result.

You could measure the resistance of the gas valve first stage solenoid if competent.

Tony

 

[Breesey]

He should have gone into the burner chamber to clean out any debris in there etc. Sounds quite likely that you do have a blocked pilot injector for this reason.
Get him back and ask him to do the service as it should have been done and to include a check/clean of the pilot injector!
If it is blocked you won't need any parts.

(Edit: Agile posted while I was typing. Sorry to double up!)

 

[ChrisR]

I won't go far into one of these without provocation. Rust, asbestos and random bits of metal tend to pile up on the floor.
There's no way you can say the boiler failed as a result of anything not having been done. If boiler was working, the pilot was clear then.
Don't even waste your time with the phone call.

You check the case seals with the case ON, by the way!

I've seen a lot more failed gas valves than blocked pilots on these.

Retail price for a new gas valve is something like £270. Which is why I collect used ones... (& which I don't sell, sorry)

 

[Breesey]

Debris should be cleared out though on a service and it remains a possibilty that the pilot has become blocked during its last firing. Would you not eliminate the possibility of a blockage here before changing the gas valve?

 

[leew]

Starting with the lowest price option first then I would certainly ask to check the pilot injector first before forking out for a new gas valve. I always like to be armed with useful information like this before being told it's the most expensive item that needs replacing (sorry no offence to anyone on here, just had bad experience with engineers in the past.)
Thanks for kind advice.

 

[bengasman]

The service was only done a few months ago from a southern electric gas engineer, from what I'd remembered the engineer just did a few basic checks he did'nt open it up to check anything inside the casing though.

Chances are that you are on a “service” contract by the sound of it. most likely they come by once a year and do a safety check.
Visual inspection, drop test, flue test and off we go. That means in reality, the boiler may not have had a true service for years, in which case, that may all it takes

 

[leew]

Engineer came to change the gas valve, thought it was sorted when the pilot flame lit up, then approx. 3 mins later the burner lit up, the engineer says the mercury valve is on its last legs and needs changing too. I can't remember if this was normal or not before my boiler broke down, can someone advise please.
He's gone away to see if this part is still available, fingers crossed

 

[ChrisR]

COuld be that the sensing part isn't in the flame properly any more. Easy to dislodge it.
If it's really 3 minutes, then that IS a long time. Yes they're available, at a price!