[?] Worcester-Bosch Greenstar 30CDi - losing pressure

We had a Worcester-Bosch Greenstar 30CDi boiler installed about six months ago. It is working generally fine but I've noticed that about every couple of weeks the last radiator in the system makes slight gurgling noises and needs to be 'bled' to let out some air. As a consequence of doing this ( I presume), the boiler's water pressure drops slightly because I then have to readjust it back to its normal one Bar level.
Is a pressure drop with time something to be expected of a system such as ours or is the air that gets into the radiator an indication that there may be a leak in the system somewhere? Should I be concerned and, if so, what is the best course of action for me to take?
Before the boiler was commissioned the installer filled the entire heating system with a chemical which was left overnight and then flushed out the next day until the water coming out was completely clean.
The central heating pipework in this house is at least 40 years old so I'm wondering if this treatment could have caused pinholes to develop in one or more of the joints. Since the leak, if there is one, is so slight (at the moment), I'm inclined to do nothing at the moment except to keep an eye on the system, but I'd really appreciate hearing any comments from the experts in this NG.
Many thanks, and a Happy New Year to all.
TIA - Dave.
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David C.Chapman - ( snipped-for-privacy@minda.co.uk)
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Have a Magnaclean fitted on the CH return pipe to the boiler. De-sludger will not remove all the sludge. If there X-400 inhibitor in the system?
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A leak should be fixed, it could be the boiler and be under warranty. For Autos there is flourescent dye you can add to the cooling system, a high intensity Black Light is used to pinpoint the leak. I am sure it is done for boilers. I would want to know what was leaking, especialy if it was the boiler. Is there a water auto feed, How much water is it loosing, what is boiler pressure cold and hot, Does pressure increase with temp or is the relief valve wet indicating it releases. it could be alot of things, even a loose radiator valve.
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On Sat, 27 Dec 2008 11:36:51 +0000, David Chapman wrote:

Take a look at the Sealed CH FAQ. You might have a tiny leak that is letting air in. You could try a slightly higher pressure to start with say 1.25 bar.
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Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
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Many thanks to those who took the time to reply to my posting. Your comments were much appreciated.
Happy New Year.
- Dave
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David C.Chapman - ( snipped-for-privacy@minda.co.uk)
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