Glowworm Flexicom 30cx recurring F9 fault. NOT PRV

[Joannebarra]

Our boiler is just over 3 years old. Last winter it had a recurring problem with loss of pressure - we kept having to re-pressurise it to get the CH to work. The hot water worked fine until the system asked for CH (either when the thermostat/timer kicked in in the morning or we switched it on manually), then that would stop working too. Always F9 fault, sometimes we could open the taps below the boiler and re-pressurise, sometimes not. Finally had an engineer round as it was still under warranty and he changed the PRV. The system was showing a high pressure 2.5 - 3.0 bar and the plumber said that was probably a faulty guage, not that the system was actually operating at that pressure. We haven't really noticed a problem over the summer, hot water's been fine and we haven't asked for CH.

The problem has now started again so we have tested the pipe outside (plastic bag on the end) and this does fill up with water. So we changed the PRV again (thinking we might have had a dodgy one fitted). The same problem, F9. We've got the hot water to work but as soon as we ask for CH it faults.... then after an hour of re-setting and re-pressurising we get CH, which works fine until it's switched off and then won't fire up again - F9 - and the hot water won't work until we go through the whole process again. Bag outside fills up when the heating is on, but not when just the hw is working. Display showing 2.9 bar, hw working, daren't put the heating on until we've all had showers!

Is it likely to be the heat exchanger, or the expansion vessel? We'd like to be sure before we start spending any more money.

 

[Billy Bob Bob]

its likely to be a faulty vessel,loop or plate heat exchanger,the flexicom is not the best boiler in the world

 

[Joannebarra]

thanks. Which would you try first - and is there anything else we can do to test which of them it might be?

 

[Billy Bob Bob]

thanks. Which would you try first - and is there anything else we can do to test which of them it might be?

you need a competent engineer to test components TBH,you could put your location and boiler fault in the need a plumber/gas engineer section

 

[bspareltd]

i would put a pump on and see if there is any charge on the vessel intially.When you charge a vessel up it is good practice to replace the blow off as well

 

[Joannebarra]

Thanks. By 'blow-off' do you mean the pressure release valve? If so, already done that. We can vent air through the small valve on the side of the vessel which usggests there's quite a bit of pressure in there at the moment.

 

[bspareltd]

if your not familiar with the phrase blow off , that tells me your not a engineer , so i would not like to give advice to novice .This is a very common fault on all boilers.

Thanks. By 'blow-off' do you mean the pressure release valve? If so, already done that. We can vent air through the small valve on the side of the vessel which usggests there's quite a bit of pressure in there at the moment.

 

[Joannebarra]

Blow-off working fine, just been replaced.
Siphon float removed, cleaned (of grit/sand-type debris) and refitted. This leaves the expansion vessel at fault? This has to be pressurised to 1.0bar before it will work.

 

[mountainman]

We can vent air through the small valve on the side of the vessel which usggests there's quite a bit of pressure in there at the moment.

Says it all really IMO

 

[Roger Welton]

Agreed

 

[dancinplumba]

lol agreed too

 

[Millsy 82]

Get an engineer in. It is false economy trying to fix something you are not sure of you have already fitted 1 part that didnt solve the problem so that was a waste of money on that part and a decent engineer may not need to fit parts at all.

 

[neily01]

its likely to be a faulty vessel,loop or plate heat exchanger,the flexicom is not the best boiler in the world

Just like gas man said.