Very high boiler pressure

[bertietheblue]

I've just come back from a weekend away to find a fault with my combi boiler - I think because the pressure gauge reads 4.5 bar. And I'm very cold.

I've bled any air from my radiators, and the pressure now reads 4.0 bar. Should I just keep on bleeding the water from the radiators until the pressure drops to 1.0 bar? If so, should I bleed each one about the same amount - so a bit of water from one radiator, then a bit from another, and so on around the house - or can I just bleed one or two?

Also, can anyone explain why this happened. It's been very cold outside and I thought water pressure in the boiler would have dropped if anything - but then my knowledge of physics is basic.

Thanks
Bertie

 

[Terry7556]

bertie at the top of the postings page is a sticky about boiler and c/h FAQs, go into it and read about repressurising your expansion vessel

 

[MisterBlonde]

is the pressure high only when heating on? if it is continuously high, check the filling loop has not been left on. if not, it could be a secondary heat exchanger fault. what boiler is it?

 

[bertietheblue]

It's a Glowworm Flexicom 30cx. I'll have a look at the sticky - thanks - but if you have any ideas in meantime please let me know.

 

[bertietheblue]

No pressure is high straightaway when I switch on the boiler

 

[bertietheblue]

I should also say water was slow dripping from the boiler when I first turned it on but that has stopped now. Not sure if pressure is too high though - although it's now 4.0 bar the manual says 'the maximum working pressure of the domestic hot water circuit is 10 bar"

 

[Terry7556]

bertie if your cold pressure is say 1.0 or 1.5 bar, then it should rise to 1.5 or 1.8 ish when hot.
at 3 bar the pressure relief valve should lift and relieve this extra pressure outside by way of the p.r. pipework. the prv is a safety device on your boiler

 

[MisterBlonde]

when you say "switch on" do you mean turn the heating on?

if you drain off some water, bleeding a rad or using the drain off you should be ok. However if it starts rising again even when heating off then u have a problem

 

[bertietheblue]

I switched on again (by which I mean simply switched on the boiler not the heating). Pressure's dropped to 3.4 bar. I've fired the heating up and 10 minutes later all seems OK - no F9 (high pressure) fault

Thanks for you tips
Bertie

 

[bertietheblue]

Bugger! No sooner had I posted than the F9 problem has appeared again! Any idea? Should I keep draining water from the rads?

 

[Terry7556]

no thats one of the symphtoms, sort out the problems thats causing it. if you dont read the sticky and follow the advice given, then call someone in

 

[CBF]

if the pressure gauge is reading correct then you have a problem with the pressure relief valve as well