Glow worm 30cxi fault

[John]

I have a Glow worm 30cxi and it keeps cutting out, the fault has been going on for some time, but we can usually restart it by switching it off, leaving it for a few minutes and switching back on. However it is now not responding to this! Is the fault common to this boiler, what are the likely causes and finally how much am I likely to be looking at for its repair? Thanks

[IMM]

Look through the fault finding guide in the instructions. They are downloadable from their web site. It could be going out on overheat. Is it in the guarantee period? They are guaranteed for 2 years.

[geoff]

In message , John writes

Do you live in a hard water area?

The heat exchanger might be getting furred up and overheating because of the reduced flow

or several other reasons

[MikeCunliffe]

I also have a 30cxi, installed Jan 2005. In Aug 2005 the water inle valve was replaced after a fault was found causing it to 'stick' in th closed position - so I could not re-pressurise after a loss (bleedin rads etc.) The valve was again replaced in Jan 2006 for same reason. A design mod. on the water inlet valve (by Glow Worm) necessitated further change in Mar 06 and thereafter I had difficulty re-pressurin above 0.7 bar. The boiler is designed to stop operating should pressure drop to 0. bar or lower, and when very cold, at night, this pressure can fall tha low. I have now had an external water filling loop installed and ca pressurise to 1.0 bar cold. The natural expansion when hot causes op pressure to be about 1.6 bar.

I'm of the opinion that the new, replacement water inlet valv assembly, having two non-return valves and an airbreak is having reducing effect upon the pressure.

Finally, after much "debate" Glow Worm have covered the installatio costs of the external filling loop and the original installer has toda installed said item.

Note, it is rumoured that water supply companies are reducing thei mains water pressure to reduce leakage from mains pipes. This could with the internal filling loop resistance cause a drop in the wate pressure available when pressuring from cold. That said, United Util tested pressure at ground floor level at 2.2 bar, and as boiler is metres higher one would expect 0.3 bar pressure loss. So, 1.9 availabl should pressureise the 30cxi to 1.5-1.6 allowing for a nominal amount o resistance resulting from the internal filling loop and now, with th external, there should be 1.9 available to it.

Still only able to pressurise to 1.0 bar cold though

-- MikeCunliffe

[Tony Bryer]

The resistance of the filling loop is immaterial. You should be able to pressurise the system to the static pressure in your water main (adjusted for storey height). A high resistance filling loop will just make this process a bit slower.

[MikeCunliffe]

Thanks Tony,

that seems reasonable. With a tested pressure of 2.2 bar (measured b United Utils) 10ft below the boiler location, and 1.2bar at the boile (measured by Glow Worm regional service manager) I fail to understan why I'm struggling to pressurise much above 1.0 bar and why there' such a pressure loss for a 10ft height difference.

Mik

-- MikeCunliffe