Sealed system losing pressure

23 Feb 2009
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United Kingdom
Hi all
Just wondered if you had any thoughts regarding sealed ch system pressure loss?

Have a basic boiler heating a Megaflo unvented cylinder and the radiators.

Situation is that I need to top up the system every week or so because the pressure drops to 0.5 bar, so a leak somewhere I would have thought.

Only thing is, when the system is running and hot the pressure never goes above 2 bar, whether it's 0.5 bar or 1 bar when cold.

Also, having observed the system over time, the pressure does seem to stabilise at 0.5 bar.

Can anyone tell me if I am missing something here?
I would have thought that if there is a leak the pressure would reduce not only when cold but also when hot?

Many thanks for your thoughts
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Have you looked at the FAQ relating to PRV vent?

You have checked its not leaking?

I've had a look in some of the FAQs but didn't see anything about a PRV vent?
Do I need to check the pipe which runs outside or is there a way to check the PRV itself?

Many thanks
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some comman place to look or leaks

1. connection on all valve underside and rad side

2. connection to radiator tails

3. blead valves

4. if not all radiators are on and you have a trv it may be off but may have frost protection

a few that came to my mind hope helps. ps also i hope you dont see any but damp patches on celing could indicate a problem with upstairs piping

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