On Mon, 05 Apr 2004 18:41:53 +0000, John wrote:


"RichardS" noaccess@invalid wrote in message
.. .
"John" wrote in message
...

"RichardS" noaccess@invalid wrote in message
. ..
Think our ageing Ocean FF combi (sorry, can't see any identifying
model
mark
other than this and the serial no. on or in the casework) is telling
us
that
it needs some care and attention, or that we ought to speed up our
replacement plans....

For a couple of days I had noticed that the hot tap needed to be
turned
further and further on before the boiler would fire into action.
Yesterday
morning it decided that no amount of flow was going to wake it up.

The boiler has a selector switch for DHW only or Heating and DHW. I
turned
this to DHW only and then back to the DHW + Heating setting, and all
was
fine again - boiler sparks into action immediately now when the hot
tap
is
opened (it's mounted on the kitchen wall, about 1m pipe run from the
hot
tap).

However, the heating refuses to fire up at all now. All thermostats
checked
and set to max for the moment - they are definitely both past the
"heating
on" clicks.

The pump is slightly warm to the touch, and I have tried the normal
percussive attack on it and twisting the spindle doesnt seem to make
any
difference.

Any hints on where to start with diagnosis/fix?


IMHO this is one of lifes nasty fiddly repair jobs. Fortunately it is
likely
to be a diaphragm assembly which has failed and a service kit is fairly
readily available. Fitting it is another matter and bits fall out
everywhere
when you start to open up the diverter block G
Good luck!


Thanks - sorry for not responding sooner but my ISP's news server hasn't
replicated any new articles for the past two days (I did see them from a
free - ie no post permissions - server that I use but couldn't respond).

What I'm seeing after further investigation is no voltage at the pump when
the heating should be on. I would have thought that the first thing that
gets fired up when switching the heating on is the pump, and the boiler
then
kicks into action from a flow sensor on the heating circuit - ie fail-safe
in case of problems with the pump. Perhaps this is not the case though.

Why would you suspect the diaphragm assembly? (just curious as to the
diagnosis)


Based on the build up period where you had to run more and more "hot" flow
to get the boiler to start. I'm guessing the diverter assembly has now stuck
in a mid to hot water only position. Only a guess from afar at this juncture
I'm afraid. Of course it might be something else entirely but then again you
could have two simultaneous faults :-(
Personally I'm not at all impressed by the model you have. Lets hope the
latest output currently being promoted from this manufacturer is built of
sterner stuff

Is this model one where the diverter valve is operated directly form the
DHW flow, so that if the diverter valve sticks then DHW mode is not
attained?

--
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