Vaillant Combi not firing - fan light blinks & goes out

[smudger11]

Hi there

Got a Vaillant Turbomax 242e. I noticed the rads had gone cold early tonight so ventured upstairs to check boiler & discovered it wasn't firing.

Switched it off & on & discovered that the fan light blinks on as if it's going through the normal firing procedure but doesn't stay on. Pump is working, fan is working but boiler not firing. Boiler pressure is fine at just over 1 bar and everything else was working fine until this evening.

Have read through the fault finding chart in the instructions & it seems to lead me to the air pressure switch which it recommends "checking or replacing".

Anyway, given a couple of bad experiences with heating engineers I'd like to be a little forearmed with knowledge to avoid getting ripped off again.

Anyone got any ideas - is it nailed on to be the air pressure switch or am I barking up the wrong tree?

Thanks in advance

Cheers
Smudger

 

[Agile]

There are several possible reasons why your boiler is not working and the APS is only one suspect.

Since all these aspects require a competent CORGI to investigate I am unable to give you detailed information.

All you can do is to check that another gas appliance such as a cooker has a gas supply.

Would you like to identify the gas engineers involved previously and how you had bad experiences with them?

Tony

 

[smudger11]

Thanks for your reply - I appreciate your points.

Further to my earlier post, rather oddly, despite not firing the boiler seems to think there is a demand for hot water (i.e. the DHW light is on) when all taps are off. Also, despite having not fired both the pump & the fan seem to run all the time. Oh, and yes the gas to the hob is fine.


Thanks again
Smudger

 

[Agile]

The hot water demand is assessed by a microswitch on the extreme right of the lower part of the boiler.

Its actuated by a ( usually ) white plastic lever operated by the diverter valve.

The white part can break, the microswitch can fail or be wrongly mechanically adjusted. Or the diverter valve can fail, seize up or break.

Tony