Hot water flow drops when boiler pressurised

[acharnley]

Hi all,

Ideal Vogue C26 Gen2

With CH off...

When the boiler pressure is minimal, enough to clear the screen (so say 0.1 bar), the hot water works normally.

If I then increase the bar to 1.0 the hot water flow halves if not quarters.

Otherwise the boiler is fine and was serviced late last year without anything coming up. Any ideas?

Cheers! Andrew

 

[acharnley]

Doh sorted it, so there's two valves to pressurise the system and one was open which restricted the HW flow but only when pressure was up. It would be cool if someone could explain it as I love to learn!

 

[terryplumb]

Whatever valve you are referring to could be the mains cold water isolation valve ,preventing cold water entering the boiler when closed or partially closed. Either would stop or restrict the hot water flowing out to taps .
The pressure gauge on the boiler shows the pressure in the heating system and has nowt to do with water coming out your taps

 

[acharnley]

For my curiosity I checked and the valve that was 'open' was the cold water isolation valve. It appears to be two way, so shunting water to the filling loop. For some reason it doesn't appear to be fully isolating though and for another mystery the pressure makes a difference to the hot water flow.