Vaillant 242E - Not igniting

[rdean]

Hi, got a Vaillant 242e and its not igniting for either hot water o

heating. It makes all the right clicking sounds, pump starts and flu fan starts (only when running hot water tho?).

I've replaced the Flame Ignition PCB and Fan Module PCB tonight, an the mainboard was replaced 2 years ago. However its still not igniting

My brother in law is a plumber and we've gone thru the fault diagnosi in the Vaillant manual, all of which lead to it being one of th PCB's.

Could it be the Thermostat PCB that is at fault or might it b something else?

Full Model No. :- VCW GB 242

-- rdean

[Ed Sirett]

The fact that the flue does not start for the CH does seem wrong. For the water heating is the sparker clicking?

[rdean]

Ed, Yes it does seems strange doesnt it, as for the water heating there are a few clicks, it sounds as if its getting all the way there but no ignition.

Is it strange that I can't see the pilot light to

-- rdean

[Ed Sirett]

There are no pilot lights on the 'E' model for electronic ignition. Some boilers with electronic ignition do have two stage ignition using a temporary pilot light - but this model is not one of them.

Leaving aside the CH problem there is a weird fault on this model which looks like a PCB failure but is in fact just a water flow sensor problem.

When the water flows it move a small piston which operates a small valve (sort of triangular with 4x 4mm pipes on it) and a microswitch. The latter starts the pump which on account of the former causes the diverter valve to shift to HW. More switches are closed this starts the ignition sequence. It turns out that if the microswitch does not maintain contact the ignition sequence is put on hold at the gas valve stage.

So the boiler appears to have a broken gas valve.

The cure is to overhaul the water flow diapragm - easy enough but there are a lot of little pipes and quite a few big ones too, and the boiler has to be drained. The book states how to do it.

You can test that this is the case by operating a tap and manually encouraging the microswitch (taking care over its 230V contacts).

This seems to be a stock fault on 242s after about 10 years.

Maybe the piston is not retracting properly and thus the CH won't go either?

HTH

[Edev]

Hi Sorry to jump on this, especially so long after it was originall posted, but it sounds a bit similar to the problem I'm having an wondered if the cause be the same.

I have a 242e or a 282e (according to the manual, can't find the mode on the unit).

When the heating is turned on, the pump runs, but the burner neve fires. If, whilst the heating is on (pump running), I turn a hot wate tap on, the burner will fire, and the radiators will start to heat up

However, as soon as the HW is turned off the burner shuts off, and th radiators go cold again.

Initially it only did this intermittently, but turning it back on afte summer, it now does this all the time.

Any thoughts greatly appreciated!

Thanks,

Ben

-- Edev

[Ed Sirett]

This is either a VCW 242 E which has a pair of switches and a black knob marked 1-9. Or it's a 'Turbomax' VUW 242e/282e This has a column of leds with various 'euroglyphics' next to each one, The control panel is black(?) plastic with turquoise(?) knobs.

This would be the symptoms of a VCW 242 with a diverter valve that can't quite make it to the CH position and so begin the ignition sequence.

[Edev]

Sorry - it's the VCW.

-- Edev

[Ed Sirett]

The valves are not too bad at around £60 or so. The work involved is complex and should not be tackled unless you have the manual to hand even if you have done a few before.