Vaillant Combi Boiler Pressure Drop

Old 10-14-05, 10:47 AM
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Vaillant Combi Boiler Pressure Drop

Hi there i have had a Vaillant Combi Boiler fitted just over an year ago and today the pressure has dropped to zero and of course the boiler wont work so no heat or hot water!!!!!.
In the space of the year this is the second time this happend and the first time under warranty the installers repressurised the boiler and everything seemed ok-until today!!!!!!!! Of course it is now out of warranty and was hoping maybe i could do the job myself as around here in the UK plumbers fees are horrendous.
Also im not too happy at this happening twice in just over an year so does anybody out there have any ideas of the cause?are vaillant boilers crap?and most importantly if it is possible for me to do the job myself what do i do????????????
Many Thanks
Old 10-14-05, 12:31 PM
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Hi there,

Dont worry too much, this is a minor problem as far a combi's go. For some owners its a routine exercise.

Firstly you need to repressurise your boiler and system via a filling loop. look on the pipework running to the boiler directly below for a silver hose. If you cant find one its because some Vaillant models have in integral fill loop wich you need the Vaillant key or a flat bladed screwdriver to operate a valve at the underside of the boiler. Open the tap on the hose or turn the key on the boiler until the pressure guage shows 1-1.25 bar then shut off the tap. The boiler should now fire with a demand.

There are user instructions which will advise you how to fill using the intagral filling loop. The installer should have left these with you.

You may need to bleed your radiators now using a radiator key as the system may have had air in it. Recheck the pressure after bleeding.

Finally, Vaillant boilers are one of, if not the best boilers your money can buy you, but it doesnt mean you will never have any problems. I have just installed a new Vaillant Combi in my house.

Best of luck

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