In an earlier contribution to this discussion,
wrote:

For as long as I can remember, one of my radiators makes a racket... I
bleed it and the noise goes away, but a few days later it comes back.

Every time I have tried to fix it (by keep bleeding it), the summer
comes and I give up.

The problem is back now and I want to fix it.. I have bleed it 3 times
this week already and again today, there is air in it?

What can I do? Where is the air coming from? Why is it always this one
radiator?

Any tips would be appreciated

All the best

Jon

First off, you need to determine whether it *is* air - or hygrogen. The
latter is caused by corrosion if there is insufficient (or no!) corrosion
inhibitor in the system. Next time you bleed the rad, collect some this
'air' in an upturned jam jar and then apply a lighted taper to it. If it
burns with a blue flame, it's hydrogen. If it *is* hydrogen, you need to
flush and refill the system, and add an appropriate quantity of inhibitor to
the water.

If it's air, it could be getting in for a variety of reasons. The most
common ones are insufficient water in the fill & expansion tank, or 'pumping
over' - where there is a constant flow of water out of the vent pipe into
the F&E tank when the pump is running. [Both of these assume that you've got
a vented - rather than sealed/pressurised - system]. If it *is* pumping
over, try reducing the pump speed. If this doesn't fix it, there will almost
certainly be an error in your pipework layout which will need fixing.

Whenever you get air - or another gas - in the system, it invariably settles
in one particular place - probably because some particular feature of the
pipework makes it easier for it to go there than anywhere else.
--
Cheers,
Roger
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