Main 24HE Intermittent flame failure from CH, but HW is ok?!

[BobbyDav]

Hi

I'm new here, have searched the forums for an answer but can't find anything the same as this problem. My Corgi plumber is running out of ideas and the manufacturers helpline is not being helpful, so as a last resort I'm posting on here!

- Boiler is a Main 24 HE (about 18 months old)

- The flame failure light comes on almost every day when the heating tries to fire up (although sometimes it works ok). It's starts to make the clicking noises but never gets going, after a few tries the boiler gives in and the 'flame failure' light appears.

- Quite often, the only way to get the heating on is to reset the boiler whilst running the hot tap, this then gets the boiler started and the heating going. Strangely, the hot water doesn't seem to have a problem in getting it fired up.

- The Corgi engineer adjusted the flame sensor down vertically slightly but this only temporarily helped.

- This has been going on now on and off for a few months.

- Just had the Corgi safety certificates and it passed ok.

- The plumber isn't sure what to try next, is this the PCB or something simpler??

Surely somebody has had this identical problem and knows what to do??

Many thanks in advance for any help

Bobby

 

[baxpoti]

What were the recorded burner pressures?

 

[Homesafe]

primary thermister?,,

 

[Agile]

You really need a boiler engineer rather than a plumber!

It sounds as if he does not know how to adjust the gas valve minimum and maximum output pressures.

Only about a quarter of CORGI people seem to know how to do it.

Tony

 

[Homesafe]

I have found most boilers i go to have not had them set

 

[BobbyDav]

Many thanks for the responses guys (or girls!).

The thermister has already been changed.

Not sure on the burner pressures. Does anybody know what these should be for this boiler??

I'm waiting for corgi man to call me back...

Thanks again,

Bobby

 

[Agile]

Hi

I'm new here, have searched the forums for an answer but can't find anything the same as this problem. My Corgi plumber is running out of ideas and the manufacturers helpline is not being helpful, so as a last resort I'm posting on here!

Bobby

Its common knowledge that "helplines" are not often that helpful unless its a very simple enquiry.

This website has some boiler experts who fix real boilers every day ( apart from Big Burner who is retired and just reads manufacturers brochures. )

I know exactly what the gas pressures should be but I am not posting that information on here in case it encouraged any illegal gas work.

Tony

 

[BobbyDav]

Having looked at the Corgi Gas Certificate from 2 weeks ago, the 'Operating pressure in Mbar or heat input kW/h or Btu/h' reads: 9.5 (no unit stated).

The one for last years certificate read: 10.2.

Does this clarify anything either way

 

[Agile]

No, not at all!

 

[BobbyDav]

Just found the manual, the pressure should be 10.2mbar so last year's was perfect, now it's currently 0.7 mbar below what it should be.

Could this be the cause of the problem then?

 

[Agile]

It is other factors than the maximum burner pressure!

 

[BobbyDav]

What are these other factors then please?

 

[Agile]

There are minimum, ignition and CH settings to be taken into account by a competent CORGI registered person.

On this particular model they are very critical for the correct operation of the boiler and a very common cause of failures after the diverter valve and it's switch.

Tony

 

[BobbyDav]

Thanks for your help, the corgi guy is coming out again in the morning.

 

[christianp]

Hi I have a main combi 24 he boiler showing intermittent flame failure, though the problem has been getting progressively worse. I've had a plumber come and look at it. I think he checked the flue and the pressure. He then opened up the PCB. He seemed to connect the joints with a multimeter so the flame ignited. He suggested that the joints were weak which would explain the intermittent operation.

He has recommended replacing the PCB and the air pressure switch. I wasn't entirely clear on his explanation but he said he tested it by bypassing the APS and then not bypassing it; he seemed to suggest that the flame did not come on when he didn't bypass the APS and is concerned that the problem would come back if he didn't replace the APS as well.

Does this sound like a reasonable diagnosis? Do I need to replace both the PCB and APS or could it just be one of the two?
Is £240 all in (parts £140 and labour £100) a reasonable amount to charge for this?
Does the whole PCB need to be changed or can you replace component parts?
Essentially, am I being ripped off?

Any help would be much appreciated.