OK. Boiler comes on and for the first 10 seconds or so, it sounds like someone is smacking the pipes with a hammer, then it runs quietly for a bit, then might start again.. British Gas came round (we have the 3star cover thingy) a few weeks back and swapped the pump, which seemed to make it go away, but now it’s back again. The guy said if it comes back, we would need to have the system ‘power flushed’. I think he was just looking for commission on an overpriced unnecessary job. The water runs clear when I bleed the rads and we have a MagnaClean thingy installed to keep the water clean. I haven’t cleaned the filiter thingy in the MagnaClean, so guess that might need doing, but why the banging noises?

So, STW hive mind, what to check next?

Air in the system, innit?

Corpse?

Sorry, yes.

Air in the corpse.

your pumps probably stuck give the bottom of pump a good clout with a hammer

It’s just payback for putting your central heating on already!

Pump seems ok, it’s new as well.

Got all the rads going now and slowly roasting the house. No air found yet in rads, banging still happening, but possibly not as intense now I’ve bleed a little off from each rad. Water I’m bleeding off is cristal clear. A bit perplexed

It’s just payback for putting your central heating on already!

It’s not on, was making th noise with just the water being heated!

I think you’ve got leak,

same thing happened to me at my old house, went on all winter, turn heating on few bangs for the first ten mins, then all ran great.

Turn heating off, air is drawn back through hole,putting new bangs in place for when heating is turned on again.

We had a new pump and then a new condenser,bled the system to many times to remember,and still got bangs.

Fast forward 3 months, and the kitchen ceiling fell down one morning, no warning, no water marks, nothing,

Turns out the radiator at the top of the stairs had a pin hole leak at the joint,and over the space of the winter the drips wet the plaster board in the kitchen ceiling causing it to fail.

So nothing to worry about really.

Is it definitely coming from the boiler?

When we moved into this house, the central heating would make one hell of a racket… that turned out to be that some of the thermostatic radiator valves had been installed the wrong way round! This caused them to hammer like mad…

If you have thermostatic radiator valves, it might be worth turning them all up to full and seeing if this cures the issue…

Other than that, it’s could be air getting into the pump somehow… where abouts is your boiler? Up or down stairs?

Look up KETTLING. You have a circulation issue, could be air, could be blockage, could be leak, etc. As the water is not circulating quickly enough the water is boiling in the boiler, i.e. not passing through quick enough, and that causes the noise.

Having the same issues myself. Have used Fernox as a temporary fix but will likely need to do something more radical if we’re lucky enough to make it through another winter.

Hmm, it’s quietened down now. thanks for the tips. Gonna need to get the pros in I think