Vaillant VCW-GB 242 E

[gowiththeflow]

I think this is the make although I can't find any data badge. It is definately a very old Vaillant combi and has the red neon switch on the left hand side of the facia that can be switched up for hot water or down for heating /hot water.
Anyway I have just fitted a new bathroom and a thermostatic shower valve that states in the instructions that if used with a combi, the boiler must be fully modulating and be able to produce water at at least 60 degrees.

All other outlets are working fine but the shower valve is not producing hot water as the boiler is not firing when the valve is operated.

Is this because this old battle axe of a combi is not fully modulating and therefore is not compatable withy the valve?

Or is it because the pressures and flow rates are imbalanced? I have piped up imbalanced supplies in the past and the valve has still worked.

Any ideas?

 

[chrishutt]

That boiler should be modulating, but it may be that the reduced flow to the shower valve is not operating the boiler due to a leaking diaphragm. It's basically a sound boiler, if looked after, so if you can find someone who understands how they work it's worth repairing.

 

[DP]

It is quite likely pressure imbalance is to blame.

VCW is a fully modulating boiler