Clanking Boiler

[gas112]

Noisy clanking boiler, banging going through pipes ,more noticable on just HW banging when boiler shuts down are all basic signs of a failing boiler stat allowing the system to get far too hot

What boiler do you have

 

[Ronald0]

I've tee'd off the feed to the 3 way valve (in the airing cupboard) with a vertical pipe approx 10" long and put an isolation valve and an air bleed on the top as described. This hasn't been very successful as you can hear the air bubbles in the pipes but very little air actually rises up the vent pipe. Maybe I should have stuck with the 22mm pipe instead or reducing down to 15mm.

There must be a leak somewhere that's letting in air as no matter how long you drain / bleed it it's still full of bubbles. I can only assume I've disturbed the pipework when I put the radiators in and now have a leak somewhere. There's no obvious leaks so I'll lift the floor boards to see if it's leaking under the floor where I fitted an extra downstairs radiator. I can hear a ticking of bubbles in the bathroom radiator which is where I tee'd off to put a new rad upstairs but I'd expect water to be visible on or around the kitchen ceiling if it was leaking upstairs.

How do I do this reverse flush?

Thanks for your help so far.

chad, bleed fitment should be at a high point on the HW circuit; ie flow to HW coil as it enters the cylinder (there are already rad bleeds on the high point of the CH circuit.

... hear a ticking of bubbles. Are you bleeding with system running? System must be off to allow air to separate and seek out highspots. Bleed with MV at mid position so that head from F&E tank pushes air out.

... reverse flush. With MV set to manual (mid position) connect garden hose up to boiler drain valve, open valve and allow water to flow up through system into F&E tank. This should take air up with it.