Glowworm 30CXI: HELP!!!

10 Mar 2010
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United Kingdom
Hi, We've had a 30cxi installed about 5months ago, it recently started to loose pressure and to add to the problem it seems to operate erratically cutting off at 0.9 bar when it should still be working until it drops to 0.4 bar. Glowworm engineer ran tests to the boiler and gave it the thumbs up, he thinks there is a leaky pipe but cannot understand why the boiler would cut off at 0.9. He suggested draining the system and injecting a self sealing product in the hope it would find the leak..
Having recently read some of the reviews on the 30cxi, I am starting to get seriously worried we have bought a problem boileR ( although some of these reviews are few yrs old)
Anybody out there who has had similar problem?
Is this boiler now more reliable than it used to be?
Would sludge in the system cause loss of pressure?
Is using a self sealing product in the system a bit of a shot in the dark?
Any comments much appreciated! PLEASE...
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First thing is 2 chk expasion vessel for charge etc.if theres no obvious leaks newear then suspect h-exchanger leaking into condensate which ive had b4.also if pressure is erratic on display i.e reading 1.5 bar then dropping to 1 bar suspect water pressure sensor faulty and again ive had b4.hope this helps.leak sealer has 50/50 success rate,but I have had success in repairing leaks internally on those h-exchangers...worth a bash :)
30cxi isn't really a problem boiler AFAIK, whatever make you go for there will be one or two that break down, and people are more likely to shout about problems than to say something is wonderful and fault-free. Sludge won't cause pressure loss, you have water escaping from somewhere. Try securing a plastic bag over the outlet of your pressure relief valve, if you have no damp patches then it could be that this is letting by, the plastic bag will fill with water if this is the case. I am not a fan of leak-sealing products, they can clog up your pressure relief valve which is potentially unsafe. Much better to try to discover where the leak is coming from.

Try the bag thing and report back...
which 30CXI is it? The standard Xi range was discontinued 2 years ago. Is it an Ultracom ??
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glow-worm 30cxi has to have a minimum pressure of 1.2 bar
check the ev is charged to about .8
Thanks for all your comments. (sorry..yes boiler is the ultracom). Expansion vessel was checked and that was ok. Will check water pressure sensor and h-exchanger and try the bag test tomorrow, will let you know how I got on.
Thanks again guys!
the CXI is not the Ultracom CXI. completely different boilers. For a little bit if reassurance search the site for Ultracom, its a quality boiler and very reliable. Sounds like you've got a leak.
...Yes it was a leak! Done everything you guys suggested and still had problem, it was the very last check I did before resorting to the self sealant! Lifted a floorboard at the very back of the house (old victorian house, was dreading finding the leak due to the network of pipe & floorboards running the opposite way to the pipes), and there it was, not massive leak but looks like it has been gradual for a while.
Will change pipe tomorrow and hopefully it should be ok once repaired.
Anyway, thanks for all your comments, this is really a brilliant forum
Why was it leaking?

Bad solder joint?

On an end feed joint?

..all the pipework look really dated, elbow joint from back room radiator underneath floorboard has been leaking for a while! Badly jointed and resting on concrete without any protection...was always told that lime in old concrete eats through copper??

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