Has my builder ruined my boiler?

[windle poones]

I agree of course it couldn't fill if the check valve was stuck . That's why I started out by replacing it. That's when I realised the Motorised valves literally take all radiators out of the circuit. Opening the motorised valves allow the system to be re-pressurised.

 

[Riley]

That would be the first thing I’d check, did the builder in fact use a gas safe engineer or just a builder mate of his that does a bit of pipework. You should have an auto bypass in place which will link flow and return to allow heat dissipation once both valves are shut. If the pressure won’t backfill round the return then it sounds like a poor system design. Ultimately without actual sight of the install it’s tricky to diagnose but fundamentally as I’ve said unless there is a non return valve some where on the system then that’s really the only reason that you can’t top up the pressure with the valves closed

 

[Riley]

What do the valves control one for hot water one for heating??

 

[windle poones]

Originally before the addition of the motorised valves the only thermostats controlling the on off of the boiler, rads and whole central heating system was 1. the boilers own internal thermostat monitoring the water temperature in the system and 2. Each radiator barring two are fitted with TRV's. When the builders plumber modified the system he installed the two motorised valves. He said they are to create two independent heated zones, but they both only work on the radiators. 1. Disconnects the radiators in the extension the other motorised valve 2. Effectively disconnects the main house radiators for heating. Turning both the motorised valves off is now the same as capping off every radiator in the house and the extension. Can a central heating boiler run correctly if it is only heating the hot water supplied to the hot water taps?

 

[Riley]

Yes because the heat will dissipate correctly. You don’t have the heating on in summer do you but you will still have hot water

 

[Riley]

In fairness he should’ve zoned the water as well as you should have temp control over that too

 

[windle poones]

If I accept what you are saying and I bow to your superior knowledge. I don't need to call the builder back. I just need a competent Gas Safe plumber to investigate and fix the problem? Know any good and qualified trustworthy central heating engineers in the North West London area?

 

[Sharp Point]

I’m not 100%, but doesn’t the divertor on those house a check valve? If so having the zone valves installed and shut, would lock it up

 

[Riley]

But not if the hot water is unzoned it would go round the coil and back to the primary return then it could back fill

 

[Riley]

Ugh it’s a combi isn’t it. Sorry you didn’t make that clear

 

[windle poones]

Yup it is a combi boiler. No water tank heating coil.

 

[Riley]

They should really have a) piped in a bypass and b) piped the filling loop to the return side as this would alleviate the filling issue slightly. To be fair when properly filling you should manually lock open the zone valves anyway using the levers on them. The filling loop isn’t really a problem as you can do the levers. The bypass is. I’m calling builder or non qualified/educated install

 

[windle poones]

I am not 100% sure on what you are suggesting, but I think you are advising that the Potterton Puma 80 boiler (Combination boiler) as installed in my system. Was probably OK before the central heating side, (Pipe and radiator side) was modified. I therefore need to call the builder back to address the issue which appears to be caused by no effective by pass fitted when the pipe work was modified?

 

[Riley]

Don’t call a builder. Builders build plumbers plumb. They have the right idea in so much as the house sounds like it should be zoned but a bypass will deal with heat once the heating requirement is satisfied

 

[Riley]

As per MIs