gloworm 30cxi over-pressure?

[OscarTango]

Hi all,

My boiler knowledge is entry level at best so bear with!

Recently had a new expansion vessel and heat exchanger fitted to my gloworm 30cxi boiler, and a replaced PRV. This was to fix the problem of the boiler losing pressure and constantly needing to be refilled.

Now I have the reverse problem, and the pressure eventually creeps up to as high as 4.4 bar and conks out. When this happens I get the F9 error code flash up. Im having to bleed (almost dry) a rad to get the pressure back to normal.

Despite the pressure it still operates for a while. It takes a few hours for it to pack up. Every so often I also get a leak when it starts back up. Though that hasn't happened for a while. The boiler guy who fitted the parts came round today and hasn't got much idea about what could be the problem.

Any advice?

 

[xr4x4]

Disconnect the filling loop.

Does the pressure rise when it's on, or off, or both?

 

[Whitespirit66]

It's an integral loop on the cxi, with a small blue knob. Agree with the above, make sure the filler isn't turned on. Especially as when the filling knob is turned on when re-pressurising these boilers, there is often a short dribble from underneath on the front left side.

 

[OscarTango]

I think mine might be an older model, my filling loop as you say seems to be built in and with two grey levers you turn to open it.

The pressure seems to rise regardless of on or off.

I've just drained a rad down until the boiler read 0.2 bar. Normally at this stage the pressure would be flashing on the display, and you'd have to refill it to get heating/hot water back. I just left it to see what would happen and the pressure has crept back up by itself to 1.3 bar in the space of an hour.

I didnt touch the filling loop and it's definately shut.

 

[Whitespirit66]

Are the levers definitely off? Try isolating cold water supply to boiler, or whole house if not poss. Take the pressure back down again and see if it rises. If it doesn't rise with cold supply off, maybe problem with fill loop.