vaillant combi fault

[LUNAT]

HELLO

(I AM NEW TO THIS )

I AM CORGI REGISTERED TRYING TO REPAIR VAILLANT TURBOMAX COMBI BOILER ABOUT 5-6 YEAR OLD.PROBLEM IS IN CH AND HW MODE BOILER COMES ON FOR ABOUT 30-40 SECONDS AND CUTS OUT ON THE FRONT PANEL TEMP SHOWS 80 DEGREES .ALSO MAKES KETTLING NOISE I SUSPECTED HW HEAT EXCHANGER SO I TOOK IT OUT BUT IT WAS NOT BLOCKED . I ALSO TRIED SLUDGE REMOVER IN THE SYSTEM FOR A WEEK BUT PROBLEM REMAINS.PLEASE HELP

 

[ChrisR]

Please don't SHOUT!
WHich hex did you take out?
did you check the pump?
is the boiler getting hot?

 

[LUNAT]

THANKS FOR REPLY

it was DHW heat ex.
I felt flow and return pipes inside the boiler they were too hot.
i suspect main heat ex but i need be sure because it is over £200.00

 

[petit_pablo]

Is the pump running correctly?
Does the heat leave the boiler when in CH mode?
Is the burner pressure correct?

 

[bengasman]

Sounds like a stuck diverter

 

[Gasguru]

Is this a Turbomax, Turbomax Pro or Turbomax Plus?

Does the boiler attempt to modulate down?

Does the thermistor resistance react with temperature change?

 

[Agile]

If you are CORGI registered then I recommend you put this in the Combustion Chamber part of the site.

Tony

 

[LUNAT]

THANKS GUYS FOR REPLY

checked pump was free.
burner pressure correct according to manual.
replaced diverter valve made no difference.
it is TURBOMAX PLUS 828 /E.
main heat ex blocked?

 

[Agile]

Have you visually inspected the pump impeller?

How do you do these jobs when other boiler engineers expect to identify the fault and fix it on one visit?

Even British Gas fix most faults on just one visit!

Tony