Vaillant VCW GB 221H Won't fire up

[ukraider]

Hi

I have a Vaillant vcw gb 221h combi boiler. After flushing out and refilling, the system worked fine for about 2 hrs firing up giving hot water and central heating. then it stopped firing up. Seems to make all the right noises prior to it firing up just doesn't. Currently have no HW or CH.

Anyone got any ides.

ukraider

 

[kevplumb]

system pressure ?
lock out ?

 

[ukraider]

Kevplumb, the system pressure is 1 bar, when the boiler stopped firing up the pressure had dropped from 1 bar to 1/2 a bar.

ukraider

 

[kevplumb]

i assume you topped it up and still no go

 

[ukraider]

Yep filled it to its current level 1 bar and still won't fire up.

 

[kevplumb]

have you tryed running the hot water

 

[ukraider]

Yep have tried running HW and tried running CH still nothing.

 

[ChrisR]

Assuming it was air/foreign matter causing problem
Is the pump bled and running?
Check the 160mA fuse (just cos its easy really)
Check continuity of the overheat stat on the left of the main heat exchanger.

At the right hand side of the boiler there's a part which moves left or right depending whether CH or HW is demanded. It presses or releases microswitches. Is yours doing that?


It's a balanced flue variety, yes - ie big squarish flue through the wall and no fan?

And.... the pilot hasn't gone out has it?!

 

[ukraider]

Chris, have checked
fuse - ok
continuity of the overheat stat - ok
microswitches are working ok
the pump is running ok (how would you bleed it if necessary)

It's a balanced flue variety, yes - ie big squarish flue through the wall and no fan? yes

 

[ChrisR]

ok
the pump is running ok (how would you bleed it if necessary)

Undo the big central screw (dribbles)

Do you have the servicing manual for the boiler?

 

[ukraider]

Pump is ok have already tired that.

 

[ChrisR]

Do you have the servicing manual for the boiler?

 

[kevplumb]

servo valve stuck?

 

[ukraider]

Yes got the original

 

[ukraider]

have checked the servo valve that appears to be working ok