Vaillant VCW 20/1 T3W - Help and advice Required?

[The831Bunny]

Sounds like theres air in the boiler. PD valve will drop back as soon as there is air at the pump impeller. Check the auto air vent cap (on top of the pump back) is loose. Give it a few taps on the aav body to loosen a possible stuck float. Also back off the large silver manual air vent plug on the top of the domestic heat exchanger (left side of boiler). This may have to be done 5 or 6 times. Turn the dhw on and off, then vent to remove all air. Top up pressure if necessary and then try the heating. LEAVE THE BOILER ON for at least 5 minutes to push any remaining air into the rads.

I cut my teeth on these boilers and they can sometimes appear to do strange things. ALWAYS fault find from the beginning though, how ever boring it is and PROVE each step, don't assume.

Cheers

Bunny

 

[The831Bunny]

As this model is conventionaly flued, please get a Gas Safe Registered engineer to carry out a service, check the fluing and the combustion air ventilation asap. This boiler MUST have purpose provided combustion air.

There are still some shockingly installed models still out there.

Bunny

 

[0308marshman]

Hello Again,

I have tried everything that you have all suggested and the final icing on the cake came from Bunny, the boiler now works perfectly. You have all made an old couple very, very happy and able to face the colder weather with heating and hot water. Thank you all so much for your magical advice, I cannot thank you enough, what a relief it is to get the boiler working.

Kind regards

Eddie

 

[The831Bunny]

Thats good news!

Do get it checked for safe operation asap though.

Take care

Bunny