is it returning fully after drawing hot wawer
they or the water section sometimes sticks preventing it operating correctly
they or the water section sometimes sticks preventing it operating correctly
Vaillant Boiler VCW GB 242EH
- Thread starter gadget_buster
- Start date
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I have exactly this model and had exactly this problem in my son's flat earlier this year. The cause was (forgive me for any incorrect terminology) the diverter valve that switches the output from domestic hot water to central heating being seized due to hardness salts. A common problem I gather. In fact there were two faults but I cannot remember the second - it was an unusual one, though, so the valve is the most likely. I had Vaillant do the job and it was a fixed price deal. They gave me the choice of a fixed price (£195.00) or a cost of job basis. Luckily I chose the former. 
Edited to say that it wasn't obvious that the valve was at fault because it appeared to work but the little pin in the centre was stuck down - it's supposed to return to the up position after the actuator lifts off it but it was staying down.
Edited to say that it wasn't obvious that the valve was at fault because it appeared to work but the little pin in the centre was stuck down - it's supposed to return to the up position after the actuator lifts off it but it was staying down.
on stripping down the diverter valve and closer examination, is the valve meant to seal the pipe that leads to the heat exchanger fully when CH is demanded? or does it use pressure on the other side of the diaphram to fully seal the line to the heat exchanger? if not the i dont think the diverter is sealing the line to the heat exchange therefore not drawing water from the radiators and no CH'ing. If that makes sence to anyone out there please help me out if you can. By the way everything in the diverter looks fine, seals, springs, diaphrams etc
jump in lads i GIVE UP
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Sorry gadget but you are trying to repair the most complex combi boiler ever produced. Being of German origin it is typically over-engineered and over-complex. It is going to be impossible to give a full explanation of the way it operates on a forum.
I suggest you get the manual from Vaillant and you may have a better understanding.
However a few suggestions:
The pump differential pressure is used to control the diverter valve - this presure is applied to the diverter diaphragm and its "direction" switched by the servo valve.
This means the water must be air free - ie the auto air vent must be working and not scaled up/leaking.
The servo valve spindle must be free to return (under spring pressure)
The ceramic disc valves (within the servo valve) must be clamped together (under spring pressure) - they can partially seize - strip down and check.
The control lines must be clean.
The control line restrictor must be clear.
The diverter valve diaphragm must be in good condition - the "rubber" can become too flexible.
The diverter components must be free to move.
The water section pin must be adjusted correctly.
The hot water microswitch must be adjusted correctly.
The microswitches on the diverter must be adjusted correctly.
and so on......
I suggest you get the manual from Vaillant and you may have a better understanding.
However a few suggestions:
The pump differential pressure is used to control the diverter valve - this presure is applied to the diverter diaphragm and its "direction" switched by the servo valve.
This means the water must be air free - ie the auto air vent must be working and not scaled up/leaking.
The servo valve spindle must be free to return (under spring pressure)
The ceramic disc valves (within the servo valve) must be clamped together (under spring pressure) - they can partially seize - strip down and check.
The control lines must be clean.
The control line restrictor must be clear.
The diverter valve diaphragm must be in good condition - the "rubber" can become too flexible.
The diverter components must be free to move.
The water section pin must be adjusted correctly.
The hot water microswitch must be adjusted correctly.
The microswitches on the diverter must be adjusted correctly.
and so on......
This man will just not take a HINT.
Go ahead remove the diverter valve. Thingmijig in it is broken. Replace same and your troubles will be over. You will then have repaired the boiler single handed with no guidance or help from anyone.
What do all thes idiots who work on boilers everyday know about boilers.
Go ahead remove the diverter valve. Thingmijig in it is broken. Replace same and your troubles will be over. You will then have repaired the boiler single handed with no guidance or help from anyone.
What do all thes idiots who work on boilers everyday know about boilers.
!! RIGHT !!
So i'm going to get a new boiler then, hey!
Any one got any good recommendation for a combi?
Maybe one that is not over engineered
One that is user friendly
One that can supply my three bedroom end of terrace house
with one bathroom
but two kids and a missus
Many thanks to all of you who have tried to help my predicament, i know it has been harsh and we've fallen out along the way, but there was no really hurt, just frustration and tears on my behalf
p.s. i think i might just sign up for a plumbing course now
So i'm going to get a new boiler then, hey!
Any one got any good recommendation for a combi?
Maybe one that is not over engineered
One that is user friendly
One that can supply my three bedroom end of terrace house
with one bathroom
but two kids and a missus
Many thanks to all of you who have tried to help my predicament, i know it has been harsh and we've fallen out along the way, but there was no really hurt, just frustration and tears on my behalf
p.s. i think i might just sign up for a plumbing course now
LEAVE THE DIVERTER VALVE ALONE AND CHECK THE SERVO VALVE FIRST
IF IT IS OK CHECK THE WATER SECTION IF YOU AINT GONNA LISTEN PLEEEESE STOP POSTING
yer doing everybody's head in
IF IT IS OK CHECK THE WATER SECTION IF YOU AINT GONNA LISTEN PLEEEESE STOP POSTING
yer doing everybody's head in
N
namsag
You be careful kev you will give your self concusion banging your head against brick wall.... gadget 95% of no heat faults on vcw 242`s are servo valve or the water section pin not fully returning to rest position . These control divertor valve . worked on hundreds of these an never had to change a divertor
OK
so if the servo works for the HW does that mean it is working ok?
so if the servo works for the HW does that mean it is working ok?
for the last time NO
it has to return to the rest position IE heating
before the diverter will work
it has to return to the rest position IE heating
before the diverter will work
N
namsag
kev could you clarify that.
namsag said:kev could you clarify that.
shurrup you been up 36 hrs and i'm growling
I've got it working now Hurrah!!
There was silt and scale in most of the parts i stripped down but finally after doing as i was told and stripping and reassembling the servo valve its working.
I did inadvertently buy a new heat cut out switch on the recommendation of someone for £25 quid which was not probably at fault, but a small price to pay considering i was thinking about buying a new bboiler Many thanks to Andy, one comment, i ddon'tdeal with these things on a daily basis like your self so i had trouble understanding what you were asking me to do sometimes, but i am happy to say it is you that gets the final glory. Thank you!!
p.s. if there is any other help i need, can i come back???
There was silt and scale in most of the parts i stripped down but finally after doing as i was told and stripping and reassembling the servo valve its working.
I did inadvertently buy a new heat cut out switch on the recommendation of someone for £25 quid which was not probably at fault, but a small price to pay considering i was thinking about buying a new bboiler Many thanks to Andy, one comment, i ddon'tdeal with these things on a daily basis like your self so i had trouble understanding what you were asking me to do sometimes, but i am happy to say it is you that gets the final glory. Thank you!!
p.s. if there is any other help i need, can i come back???
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