Vaillant VCW-Sine 18 T3WF H High Pressure Problem

[sid123]

I have recently had a problem with the pressure in my combi boiler - vaillant VCW-Sine 18 T3WF H. Woke up with no pressure so I topped it up to 1.5 and put my heating on - the problem is the pressure keeps on rising to the stage where I have to switch off (within 2 mins of switching the heating on)..

Hot water is fine, the pressure increases by approx 0.5 and remains.

Only thing I have done is bleed one of my rads the day before as no hot water was running through whatsoever.

Any advice greatly appreciated.

 

[Gasguru]

On this boiler I would only advise topping up to 1 Bar maximum with the system COLD. When the rads. are hot ideally the pressure should not rise to more than 2 Bar.

If the pressure is rising quickly then it is likely the expansion vessel is flat. The radiator you bled the air from was absorbing the expanded water volume and it can't do that now it's full of water.

Read the "Plumbing Tips" section on re-charging the expansion vessel.
On your boiler you will need to remove the left side white casing. The air valve is normally located on the left near the frame. I think you sometimes have to bend the frame slighly to get the pump on.

Check the white top casing on the top, any cracks etc and the boilers scrap...must be 25 years old or more.

 

[bengasman]

2 minutes souinds very short for such an increase in pressure. does the return pipe get very warm at some distance from the boiler? it sounds like your pump is not doing a lot. as far as i know, the last of these was made in the late eighties so it is old indeed. a lot of mechanical and hydraulic valves and levers, quite tricky to work on if you do not know them. unless you can find an engineer who really knows these babies, you would be better off getting vaillant out for fixed fee.

 

[Agile]

I think that most knowledgeable engineers are quite comfortable with this model.

Its the later 221 which baffles more people.

Tony

 

[pannierstan]

2 minutes souinds very short for such an increase in pressure.

Its not. Unfortunatly what nobody has mentioned is that the expansion vessel is probably knackered and the diaphragm perforated.
The OP could try it though.
Agree with Tony lovely old boiler this. Fit a remote expansion and keep the thing running for another 10 years. It will probably out run an ecomax

Stan

 

[namsag]

SO ToNY. what baffles you about the 221 that you can`t transfer over from the 242 . they both work the same apart from one has a permenant pilot. how can we help you

 

[Gasguru]

Unfortunatly what nobody has mentioned is that the expansion vessel is probably knackered and the diaphragm perforated.

These vessels are German Winkelmann and Panhoff, leagues above the likes of Zilmet and CIMM, I've not yet found one that has perforated even though they're 25 years old, initially you often get a little water from the VCW's but they hold their charge.