Boiler help needed!

Texx

Super Moderator
Does anyone know much about combination boilers? or a Glow Worm 30ci to be more precise.
 

Texx

Super Moderator
Last weekend the boiler lost pressure and shut itself down, after resetting the thing and filling it to a pressure of 1bar it fired back up and seemed to be working OK. The following day it had lost pressure once again and wouldn't fire up, so I drained the boiler checked the pressure in the expansion vessel (should be at 0.5bar according to the destructions) which appeared to be about right, refilled it and fired it back up. About 5 minutes later I went outside and noticed water dripping from the discharge pipe, so I shut the boiler off and drained it again, removed the PRV cleaned it out (wasn't expecting much of a cure but thought it was worth a go for a temp. fix), put it all back together and all seemed well with nothing leaking. The following day the pressure had dropped back down to 0.5bar and it wouldn't fire up, so again I refilled it to 1bar and off it went, but this time water was running quite quickly from the discharge pipe. So I thought it needs a new PRV, so I ordered a genuine Glow Worm PRV and installed it last night after work. Filled the boiler fired it up and it ran lovely, jobs a good'en I thought. However after it had been running for around 4 hours (no leaks) with the heating set to 20°C (boiler was reading a constant temp. of 59°C) I shut it all off and noticed the status LED on the boiler flashing green and the system pressure was reading 2.8bar.

Now I'm no boiler expert, but seeing as the PRV cracks at 3bar, a system pressure of 2.8bar seems a little too high for my liking? What would cause the pressure to rise so high, or is this normal? When I got up this morning the pressure was reading 0.9bar.
 

dac69er

Super Moderator
my boiler normally runs at about 2 bar and my thermostat is at 19 degrees. when you got up this morning was the boiler off?

how old is the boiler?
 

joshhayat

Fresh Recruit
sounds like your expansion vessel is gone. put your boiler on full and watch pressure gauge for about 15 min until boiler gets up to temperature. if the pressure is rising to fast your vessel is gone.
 

Texx

Super Moderator
my boiler normally runs at about 2 bar and my thermostat is at 19 degrees. when you got up this morning was the boiler off?

how old is the boiler?

It's getting on a bit now, probably around 6-7 years old. The boiler was off this morning, had been for approx 6 hours.


sounds like your expansion vessel is gone. put your boiler on full and watch pressure gauge for about 15 min until boiler gets up to temperature. if the pressure is rising to fast your vessel is gone.


The problem with trying this is that the display only shows the pressure when the boiler is in stand by, once it's fired up the display switches to give a temperature reading.

I drained the boiler via a small black tap on the bottom (the blue tap is the filling tap). Basically opened it and let it run into a bucket and then closed it once no more came out, then I checked the pressure in the vessel. The air pressure in the vessel was close to 1bar, but I let some air out to set it at 0.5bar because that's the pressure stated in the manual.

Did I not drain the boiler correctly before checking the air pressure in the vessel?
 

Texx

Super Moderator
Had the boiler running for about 15 minutes, the pressure reached 3bar and the new valve cracked open. Just pulled that pipe out, it was blocked solid. Cleaned it out with a wire coat hanger and all seems good. :)
 
3 bar? These boilers arnt built to take that pressure. At 2.5 bar a warning light will come on( flashing red light I think). You should lower it to 1-1.5 bar. Also u let the pressure out ur expansion vessel? Down to 0.5bar? When the boiler was hot or cold? Also if its blocking pipes you should realy t hink about fitting a magnaclean mate. my guess is the expansion vessel is burst.
 
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Texx

Super Moderator
It's been running for over 2 hours now and hasn't risen above 1.3bar. The fexi pipe connecting to the bottom of the vessel was blocked solid (have ordered a replacement), so effectively the boiler was running without an expansion vessel hence the pressure kept rising until the discharge valve cracked open.

When I pulled the pipe off the vessel (after draining the boiler) it dumped out a good few litres of water. I let the air out of the vessel and then pressurised it back to 0.5bar (the water that came out of the vessel was stone cold). The blockage in the pipe didn't take much to shift, it was a slight build up of this hard black shit. At least it's all sorted now and I've got some heating for this so say upcoming cold weekend.

The warning light (flashing red LED) only comes on when the pressure drops below 0.5bar, it'll pressurise itself until the valve opens. Seems like a bit of a dodgy design tbh.
 
Didnt realise it was that pipe that blocked mate, it will never happing again if you fit a magnaclean Though. I have never seen that pipe block in allmy years.
 
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