Vaillant VCW GB 242 EH hot water problem

[Don2]

Hi
Please help !
Boiler fires when hot water tap is opened but the flame knocks off after 30 seconds or so. Diverter vale and the micro switch works fine. cleaned the flame section, bled the sysytem. Checked the dHW expansion vessel (the small spherical vessel with the valve) nopressure is indicated. No leaks anywhere. could the fault is lackof pressure in the expansion vessel ? Should I repressurise the vessel using a foot pump to 0.7 /0.9 (10 to 13 lbs per inch) or could the fault be somewhere else.

 

[DP]

cleaned the flame section,

How did you do that and why?
This boiler has your average heating engineer want to slash his wrists unless he is familiar with squence of operation and here you are wearing two eyepatches walking in a minefield

Put away your Tonka Toy screwdrivers away and go search someone who loves this boiler

 

[Agile]

The DHW mini EXV needs to be pressurised with air while the water supply is turned off and hot tap open.

It is ideally pressurised to about 1/2 of the static supply pressure.

They are often supplied pressurised to 3.5 bar.

But with a footpump its usually difficult to get more than about 1.5 bar.

But they can be removed and taken to a service station.

But your fault is nothing to do with that part! Needs a competent engineer.

Tony

 

[Bunnyman]

Oh tony ffs stop talking, all these valves were depressured to stop noise when ever a vaillant eng comes across em