Challenging - Intermittent Central Heating Problem

[pank0906]

Hi,

I am looking for some advise for an intermittent central heating problem. So far 4 senior engineers have visited 3 from insurance company & 1 privately & none could diagnose the issue. Below is the snippet:

Problem - Boiler runs for few minutes sometimes hours & then cuts out & goes into lockout mode.
Boiler make is Baxi main 15 HE - system boiler - installed November 2007 by previous owners

First Plumber Visit - Within 10 minutes engineer said the circulation pump needs changing as the boiler is running fine. Pump changed, system ran for a day just fine & then same problem reoccurred.

Second New Plumber Visit - Within 10 minutes engineer said the air pressure switch needs changing. Air pressure switch changed, system ran for a day or two just fine & then same problem reoccurred.

Third New Plumber Visit - Within 10 minutes engineer said now then you must have sludge in your system, power flush required. Insurance won't cover for that so get quotes & get it done privately.

Fourth New Private Visit - Called for Power flush so he drained the system, clear water coming out, no sludge in the radiators so he called off power flush & said not required. He cleared header tank which had some rust, checked cold water tank which was clear. Buffed boiler from inside & cleared any dust etc (serviced it essentially), checked flue & stick a little print out from his machine to the boiler (edit), installed magnaclean, poured inhibitor 1000.
Reset & Hurray Boiler working again but I knew it may not last long, come morning it's again in lockout mode .

We don't want to change the boiler as that should not be required. What's your thought & what are my options?

Thanks

 

[picasso]

None of them have a flue gas analyzer ?

 

[pank0906]

Fourth one did check the flue as well & attached a print out from his machine to the boiler. He said it was fine too - sorry missed to mention it earlier.

 

[scatmanjohn]

So far 4 senior engineers have visited

. Always makes me chuckle. Define "senior"

 

[Agile]

Customer's definition in this case:-

"An engineer old enough and experienced enough to get customer to pay for something which does not solve the problem!"

 

[Agile]

Of course what you really need is an engineer with diagnostic skills.

But intermittent faults can be a little tricky to find.

Surprising none of those four were apparently BG trained or they would immediately have said PCB as they are expensive bits!

Good though the power flush guy was honest enough to stand up and say it was not needed. Takes a very honest one not to take your power flush money first and then tell you it was not needed. After all you will have called him and TOLD him to power flush it.

Tony

 

[Agile]

Inhibitor 1000 ?

Is that a leading brand?

Not one that I have heard of though.

 

[pank0906]

Well he didn't do the power flush but still left us with a considerable bill of £200 (excluding parts).

Now we don't know what our options are since so far we have spent much & got nothing in return.

 

[45yearsagasman]

Surprising none of those four were apparently BG trained or they would immediately have said PCB as they are expensive bits!

What an idiotic statement, meaning what precisely?

 

[moresby40]

I would say on a 15 he,the heat ex is probably the same as a 133,barcelona etc,one of the main problems with these models is the failure of combustion door seals/sump seals/flue seals which generally manifest as a fan sensor o/heat fault.As a BG eng,the LAST thing I would look at for this fault would be the PCB.

 

[pank0906]

Thanks moresby40. I will get that checked out.

 

[gas112]

as moresby says and its quite a common fault on these