Vaillant VCW GB 242E

[z9iain]

Hello all. I have a problem with my vaillant combi boiler. It has an intermitant fault with the hot water, the heating side appears to be ok. 50% of the time it works ok but sometimes when h/w has been used and then when it is called for soon after the fan and pump run (suggesting to me the diverter is ok) but the boiler takes ages to fire. I have fitted a new thermister which made a slight improvement. Sometimes when the boiler is not lighting a gentle tap on the front panel seams to get it going (this may be just a coincidence as sometimes it does not work) i suspect this may be a PCB fault but which one as there is 5. i have checked the pin which is pushed into the gas valve and the small bore pipes around it from the pump all seam clear as advised by vaillant. Also i think i need to lower the start gas pressure as it comes on around 3.5mbar then rises to to its max. Is it possible to get the boiler to run on the low gas rate so adjustment can be made ?

 

[Deleted member 105431]

sounds like a job for vaillant-i suggest you give them a call and ask for a fixed price repair.

 

[z9iain]

Thanks for that but i realy could do with fixing the boiler myself if possible.

 

[Deleted member 105431]

Thanks for that but i realy could do with fixing the boiler myself if possible.

ARE YOU CORGI REGISTERED?

 

[Corgigrouch]

Are you sure that you should be messing around with gas? This is RGI territory only..

 

[z9iain]

Thanks for the replys. this is the embarrasing bit i am corgi registered and spend my days as a breakdown engineer, but on my patch we only have 3 or 4 of these boilers and has been said on these pages befor these old combi's are very complicated compared to a new condenser or an old BBU. trouble is this boiler is my own.

 

[Gasguru]

When there is a DHW demand does the diverter move sufficient to operate the microswitch on the diverter (remove the clear plastic cover).

For info on setting the min/max burner pressures sign up for the combustion chamber and post in there.

 

[Lemond2008]

Definitely check what GasGuru says. My Vailliant VUW242 would not fire up occasionally for the hot water, and it just turned out to be sticking microswitch which I cleaned and has now been working fine for four years! The best bit is it is easy to see if this is operating so you can check this problem

 

[petit_pablo]

If your an RGi then why not ring vaillant tech help?

 

[z9iain]

Just signed up for combustion chamber.
as for the micro switch i think is working ok like i said the pump and fan work on demand but there is no ignition and gas valve does not open . i am just off to recheck this again but being an intermitant fault it is going to be a pain to find

 

[Deleted member 105431]

i would recommend you change the servo valve and clean out the small copper tubes to it. the metal punger/spindle comes with a new servo ant the microswitch does have a degree of adjustment. These boilers are complicated but very well made and engineered.