Worcester Bosch 240BF Problems!

[ecpcsb]

I have a Worcester Bosch 240BF Combi Boiler. Apart from changing the rubber diaphragm of the diverter valve I’ve never had a problem.
Last week I was getting no hot water. The only way to get hot water was to run the hot water tap, and flick the hot water switch on for the boiler to fire up (the boiler would stay fired up even when the tap was turned off, and all my radiators heated up even without the heating on). The advice I received was that the complete diverter valve needed replacing.
So, the whole diverter valve has now been changed and when I turn the hot water on, the boiler fires up as normal, and with turning the tap off the boiler fires down. So great….
But now when the tap has been running for a couple minutes, the boiler makes a bit of a banging noise, water shoots out of the overflow outside, the boiler fires down and the pilot goes out!
Help please!

 

[Agile]

Is it correctly pressurised?

Who gave you the advice to replace the diverter valve?

What advice do they give you now?

Tony

 

[ecpcsb]

Hi Tony, I got the advice from several forums including this one.

I'm just going to bleed all the radiators and then re-pressurise the system. Not sure if the boiler itself can be bled?

 

[Agile]

Is the pump running?

See FAQ.

 

[ecpcsb]

The pump seems to be working fine, you can hear and feel it running

 

[ChrisOxford]

Going back to what Tony said, what's the pressure when the system's off and cold, and how does it change when the fault occurs and the PRV opens?

Is the expansion vessel (EV) pressurised correctly... or full of water like mine was?!

Presume you've got the Manufacturer's Instructions? You can download them from the Worcester Bosch site.

C.

 

[doitall]

The problem is circulation ChrisOxford.

Air in the boiler, probably the auto air vent closed, or a stuck pump.

 

[ChrisOxford]

Thanks, DoItAll, that makes sense