Mayur wrote:

Ed Sirett wrote in message ...
Mayur wrote:

Over the past couple of days our valliant boiler has developed a
strange problem. When the ch comes on in the morning and the hw is
being used at the same time, some how water is getting into the ch
system and the pressure in the ch system goes upto about 4 bar and
then starts overflowing via the over flow pipe, at the same time the
boiler is making a funny noise.
What we have been doing when this has been happening is reducing the
pressure by opening the ch drain valve and once we have done this,
then its OK and continues to work.
We have had problems in the past with the boiler, its started off when
the pilot light kept going out and that sorted itself out, then its
was the rads getting hot when the ch system was off ? the only part we
have changed since having the boiler is the diaphram. I changed the
filler loop just the other day but that didn't help, could this be the
diverter valve ?

I'm guessing you have a VCW?
I would greatly suspect that your new filling loop is continuously
topping the primary circuit.
The diverter valve is having problems but when the primary pressure is
brought under control things may get better?

ACTION:
1) Fix the inlet loop problem.
2) Add corrosion inhibitor to the circuit ASAP.
3) Get the air out.
4) Check for correct operation of the diverter valve. Replace as
necessay.

How long since this boiler was properly [1] serviced?


[1] I don't mean sniffed at by BG with a combustion analyser.

I'm a bit confused now, let me clarify a few things

On Sunday
the reason I changed the filler loop is because I thought the valve
had stopped working properly. On Sunday the handle on the vavle
snapped off and then when I used a set of pliers to turn it, it just
wouldn't open or close. I thought it was stuck in the close position
so I left it but come Monday morning it started topping up ? I'd
suspected that some how the valve had become open and started the
topping up process.

Monday evening I changed the filler loop. On inspection, the filler
loop looked valve was ok ? using pliers open and closed the valve ?

Tuesday morning same problem !

It did it Weds morning but this morning it was fine.
Inhibitor was added to the system around the same time last year and
all the air from the rads has been removed.
What is a VCW ?

A particular model of Vaillant combi which has (IME) a tendancy to run
the CH on its own accord.
Fixable with a new PCB.

--
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