Vaillant 242 VCW GB

[4G63TSigma]

Hi, I have the German Combi in the subject heading, I had a problem before with the DHW which I solved by replacing the heat exchanger a year ago no issues until a couple months back when I lost CH, although I was regularly topping up the pressure from the silver braided inlet

Today i took it apart needless to say to no avail, although I did get a thorough lesson in combi systems at least

I noticed something that I wanted advice on, I pushed the micro swith on the servo valve as far as I could to the anti clockwise (as if facing in the picture) and the CH outlet pipe became hot but there was a sound like crackling ( simliar to pouring cold water over a frying pan ) coming from the top of the hot water cylinder as if it was empty. Im at the conclusion that the cylinder wont fill and there for the it wont light up as theres no water flow. I have a feeling the cylinder being empty has something to do with the pressure drop

this is the switch I pushed against the spring force and got some heat with no water in the cylinder
Any ideas?

 

[kevplumb]

outlet pipe became hot but there was a sound like crackling ( simliar to pouring cold water over a frying pan ) coming from the top of the hot water cylinder as if it was empty. Im at the conclusion that the cylinder wont fill and there for the it wont light up as theres no water flow. I have a feeling the cylinder being empty has something to

what hot water cylinder

 

[4G63TSigma]

whats on top of the combustion chamber then, isnt it a tank with water??
sorry its been a long day im not thinking very well but I had to post asap im FREEZING lol

 

[Boilerman2]

Freezing??? hope you get it fixed before the weather turns cold then!!

Looks like the pump differential switch you are poking so check out the water pressure and make sure the pump is working

 

[4G63TSigma]

Freezing??? hope you get it fixed before the weather turns cold then!!

Looks like the pump differential switch you are poking so check out the water pressure and make sure the pump is working

im pretty sure its the servo valve and when I pressed the switch the combustion chamber fired, pressures the and pump gets mega hot?

/edit I did take it off with the water valve underneath check them out, pretty clean no scale, switch' spring has good tension and moves freely

 

[kevplumb]

Looks like the pump differential switch you are poking so check out the water pressure and make sure the pump is working

its not

m pretty sure its the servo valve and when I pressed the switch the combustion chamber fired, pressures the and pump gets mega hot?

it is

and when you tryed this little test did you have a hot tap running

ooh let me guess no

Today i took it apart needless to say to no avail, although I did get a thorough lesson in combi systems at least icon_rolleyes.gif

think so

whats on top of the combustion chamber then, isnt it a tank with water??

no its a air to water heat exchanger

 

[kevplumb]

the noise you heard is the heat exchanger overheating because if you press the servo valve as you say all the heat is going thro the dhw heat ex and back to the same

as you did not have a tap running = no heat loss = overheat= proves jack

 

[4G63TSigma]

could it be that the bulb with copper pipe to the servo is not pumped up with enough air? my learned brother told me not to open it but I never learned by reading/listening too well lol, thats not to say I would deeply appreciate a manual link

 

[kevplumb]

thats the dhw expansion vessel

what are you trying to achive ??????

whats the problem

you get the mi's when you tell me what your trying to sort out

so there

 

[4G63TSigma]

thats the DHW expansion vessel

ahh so my bother is indeed a learned fellow he said it was for the dhw, so the problem could be CH expansion vessel (big red water with Schroeder valve @ bottom) and this would explain the regular drops in pressure maybe.

So my problem is I have hot water DHW no problem very hot but no CH the red indicator light doesnt come on when we try to turn on the CH?

/edit thanks for the constant replys kevplumb, can I ask you why there are two micro switchs on the diverter, when everything is off only the bottom one is depressed when I turn on either DHW, CH or both the diverter moves to the right and neither switch is depressed?? im guessing if the diverter moved to the left depressing both switches that might help my cause

 

[kevplumb]

there is only one red indicator (excluding the lockout light)

and thats for power on

constant pressure drop and the prv dripping points to the ex vessel either failed or needing recharging

no ch but hw points to the servo valve /water section as in your edit

try pushing the cam (the black bit on the back) on the servo down as in clockwise as you look at it

 

[4G63TSigma]

there is only one red indicator (excluding the lockout light)

and thats for power on

constant pressure drop and the prv dripping points to the ex vessel either failed or needing recharging

no ch but hw points to the servo valve /water section as in your edit

try pushing the cam (the black bit on the back) on the servo down as in clockwise as you look at it

Ok You Sir ARE THE MAN, radiators are well warm. No manual required!! Can i ask you one last thing, what do i need to change;
The return spring on the servo valve or
water section underneath because the when I opened this there was a white valve with little round holes and a long tip and it felt a little stiff

Since youve been so kind i hope you dont mind me asking for shove in the right direction with regards to filling the CH loop with corrosion inhibitors .. youve made a budding engineer very happy

 

[kevplumb]

Ok You Sir ARE THE MAN,

close i am old

fitted the first sine 18 in the town i used to live in a lot of years back

you need to check the pin in the water section (the silver disk) under the servo valve is returning properly

it is adjustable if you read the info ive sent you if there is no gap between the cam and the pin strip the water section

tip when you dismantle anything clean it and lube it get yourself some silicone grease and use it

inhibitor i would get some cleanser in first
then drain then inhibitor

all comes in the same packs

ang on im gonna edit this

 

[4G63TSigma]

thank you kevplumb

 

[kevplumb]

View media item 16004
sorry forum locked up on me