boiler loosing pressure

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my baxi combi has been loosing pressure recently, as other night it was under one bar and so ive filled it up this week and it was up at two bars, it is now down to one bar.

why should it loose pressure?, system isnt old all radiators are new, i cant find any leaks in the pipe work and the boiler isnt leaking.

Anyone have any ideas?, just wondeing what i should do,
 
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Could u explain what the auto air vent is and u mean leaking air or water?
and what do u mean by pressurised vessel, dont mean to sound think
 
If you want to understand how a combi boiler works look in the FAQ topic or the Wiki on this site. Otherwise you'll need to find a heating engineer who understands how combis work.
 
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i know how they work but just dont understand some of the terms!
 
Bit of a contradiction there old chap!

The auto air vent would be leaking water if it is buggered so reducing system pressure. It is designed to let air out but can't do this for ever.

Vessel pressure should be checked with system px at zero and in accordance with the manufacturer's instructions. However, you would only need a bike pump to charge it.
 
Boiler seemed ok for a bit then has needed topping up with a fair bit of water. no leaks.

what i have found out is there is a large amount of water coming from the exit pipe.

Is this normal?, if not what could be causing this?
 
If it is losing the water out of the prv when the pressure is lower than 3 Bar then it could be a faulty prv.

If the pressure is >3Bar then there is a fault in the boiler
 
Paul,

First off, the condensate pipe is designed to let water out of a condensing boiler. So seeing water coming from that pipe would be normal.

Secondly, you say the boiler is losing pressure. Are you sure the PRV is not letting off water? It is designed to blow at around 3 bar. I know you said you filled to 2 bar but it has steadily dropped. You should only fill to between 1 and 1 and a half bar normally. If the PRV has blown for some reason then it could now be stuck open. Often the PRV gets bits of system debris logged on the valve seat. This prevents the valve closing completely and thus the system will constantly lose water.

I know you say you know how boilers work but just check outside. You are looking for a copper pipe probably coming from the wall at the same area as the boiler. It will probably be bent down the wall. Is there a drip, trickle, steady stream of water from that pipe? If so I'd bet on the PRV being jammed.

Hope that helps.
 
The condensate pipe should only discharge water when the boiler is running, check its not draining water from there when the boiler is off - if so the heat exchangers leaking.
 

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