Vaillant 242 e problem getting worse

[hunimonstr]

Last week my vaillant boiler started to play up, it would not start and showed an orange flashing light next to the ignition indicator.
an on off usually sorted this.

I got a copy of the manual which included a fault finding flow chart.

this stated to turn water and heating onto full temp, and to turn the remote thermostat up to the point to engage the heating.

on doing this the heating demand light lighted, the pump and fan both started, but ignition often fails...

the fault finding flow chart suggests that :

Check air/flue gas system is correctly
fitted and not obstructed.
Check Pitot tube ( in fan outlet) and air hoses are not
obstructed and are correctly aligned.
Check or replace air pressure switch.


well the flue is straight thru the wall to outside and there is nothing obstructing it.

and the pipes from the pressure switch seem ok outside the combustion chamber.

I want to inspect the fan and tubes within the combustion chamber but in order to do his i must remove the combustion chamber front.

Is this recomended for a non gas engineer such as myself, Im a practical chap but my engineering quals are all math based (s/w engineer)

if neccessary I feel able to unscrew the single screw retaining the air pressure switch, and refit the air pipes, all outside the combustion chamber. But if the pipes are kinked within still i will continue to suffer the same problems.????

Also after a quick hunt these air pressure switches part no 05 0557 seem to cost £50+ ???? can anyone confirm this is correct, it seems a hell of a lot for what can only be a bit of plastic and a diaphragm???



many thanks in advance

 

[Bunnyman]

Pd valve pipes prob blocked common this model u have to drain it an clean em out either that or sticking pump ignore the fault tracing that's wrong

 

[hunimonstr]

Pd valve pipes prob blocked common this model u have to drain it an clean em out either that or sticking pump ignore the fault tracing that's wrong

OK so i got my meter out and bridged the air pressure switch contacts, this dropped voltage every time whether the bioler started or not.

I then repeated this test on the pressure differential switch, and when the boiler fired the voltage dropped but when it failed to fire this voltage remaind constant.

Also the pump makes the same sound when the boiler starts as when it does not.

does this validate your diagnosis as i suspect it does??

Thanks again in advance

 

[Bunnyman]

Yes mate when pump runs it should lift the White arm on the pd switch if it don't the pipes will be blocked on the ends or actul holes in switch blocked where pipes go in poke em out with an Allen key

 

[hunimonstr]

Yes mate when pump runs it should lift the White arm on the pd switch if it don't the pipes will be blocked on the ends or actul holes in switch blocked where pipes go in poke em out with an Allen key

Oo The white arm seems to be stuck in the raised position?? is it a visible lift that takes place? whats the resting position? under the white arm is a black beam with a raised point that looks like it should meet the white arm at rest?? - it doesnt!

tho after giving it a little manual adjustment(wiggle) the boiler has fired up every time... 4 times now, got the washin up done, and am runnin a bath

thanks again for your input, i will have a chat with a pal and arrange a servicing session, drain the system and clean the dp switch and also the pump, both have crusty deposits...

are there seal kits needed for such a proceedure?

 

[Bunnyman]

No special kits needed but ur in the right area now good job u didn't waste ur money on an air press switch spend it on the service insteD

 

[Vaillantman1997]

VM