I have an old back boiler that, after draining down and refilling the CH
system, is now making annoying gurgling noises, which I don't think it did
before.

The noises sound a little like water boiling, and they start a couple of
minutes after ignition. Everything else seems to work fine.

Is this anything to worry about? If this is air inside the boiler, how do I
get it out? The back boiler is just a box with pipes, no bleed holes.

Thanks, Bart.

"Bart C" wrote in message
...
I have an old back boiler that, after draining down and refilling the CH
system, is now making annoying gurgling noises, which I don't think it did
before.

The noises sound a little like water boiling, and they start a couple of
minutes after ignition. Everything else seems to work fine.

Is this anything to worry about? If this is air inside the boiler, how do
I get it out? The back boiler is just a box with pipes, no bleed holes.

Thanks, Bart.

The noise is commonly known as 'kettling' - on draining down you've
upset/moved/shifted calcium depostits and/or sludge into the heat
exchanger - very common on older systems. Treat with the appropriate Fernox
or Sentinal additives into the header tank (once partially drained down of
course), or a squirt of washing up liquid used to work in the old days.
Beware however, you must flush the additives out or they'll eat away at any
pin hols on old rads. Maybe a PowerFlush maybe necessary?