Answers in text :-)
hi
>
> my bedroom radiator makes some tapping noises, not that loud, but
> sometimes enough to wake me in the morning... so i'd like to silence > it if possible
** Couple of possible reasons: (1) This is expansion noise from your pipework - as the opper warms up it expands and it can 'catch' on joists etc. then release itself, which gives a sort of creaky/tappy noise. (2) A valve on one of your radiators is 'flapping' - we have at least one of these. You can hear a 'tap tap tap' noise which I think is the bit of the valve which regulates the flow (i.e inside the pipe bit to/from the raiator) opening under a build up of pressure then closing as the pressure is released. A marginal situation where the valve is almost closed but not quite. We have TRVs on all radiators so I assume it is one of these. Problem is you can hear the noise at most of the raiators, so tracking down the errant valve is not straightforward. I guess I would have to fully close each TRV in turn until the noise stopped. Never bothered me enough to try :-)
**
i tried bleeding all the radiators - the bedroom radiator itself
> doesn't bleed any air...
>
> the radiator in the bathroom (this radiator is 'always-on' in the
> circuit) seems to collect quite a bit of air over a period of
> weeks/months - is this anything to be concerned about, or is it just
> the way things normally are...?
** I assume you have inhibitor in your system? We used to have a radiator which always neede bleeding, but when I flushed the system and added Fernox this cured the problem. So it could be gas generated by the corrosion inside your radiators.
**
afaik the boiler is fairly ancient (Baxi WM 532 RS, about 20 years
> old?), but (again afaik) the pump was replaced relatively recently
> (about 3-4 years back?)
**AFAIK this shouldn't make a difference *
just been searching on this subject, seems to come up quite a bit...
> i noticed that a couple of months back, someone mentioned:
>
> >From: BigWallop (spamguard@_spam_guard.com)
> >Subject: Re: Central Heating noise waking me up!
> > > If you're only bleeding the system from one radiator, then you're not
> > bleeding all the systems properly. You will have to bleed everything on the
> > system to make sure you're getting all the air out, and that includes the
> > boiler itself. You will find the boiler has, or better have, a bleed point
> > on the highest part of the pipework for this very purpose.
>
> where exactly should i look for this bleed point - what should it look
> like, how does it work... (does it use the same key as the radiators > use?)
**No idea - never seen one **
someone else suggested:
>
> >From: Alan Campbell ( snipped-for-privacy@mullen.demon.co.uk)
> > You could try turning the pump speed up to max for a couple of hours.
> > This might help shift any air.
>
> how is the pump speed adjusted?
** Normally a switch or dial on the pump - rocker switch for slow/fast option or dial for multi-speed pumps **
any other suggestions?
HTH Dave R