On Thu, 16 Dec 2004 23:22:12 +0000, rdean wrote:


Ed Sirett Wrote:


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

--


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 too

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

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html