"Set Square" wrote in message
...
In an earlier contribution to this discussion,
David W.E. Roberts wrote:


(i) from the top:
SNIP
Disconnect the feed pipe from the bottom of the tank, and connect a
hose pipe to it with a jubilee clip.
Other end of the hosepipe on a mains cold tap. This will pressurise
the system and then you can bleed all the radiators and hopefully
clear all the air out.



Er.. what about the expansion pipe? Unless I'm missing something(!),
rather
than pressurise the system, mains water will flow up the expansion pipe
into
the header tank - and will promptly pee out through the (now open) bottom
connection!
--
Cheers,
Set Square

Good point - I am now racking my brains to remeber how I did this when I had
to clear my system out.

My first guess would be that I put a bung in the hole out of the tank, or a
stop end where the copper was disconnected from the tank coupler. However to
pressurise the system you would have to close off the expansion pipe as
well.

Second thought is that I had my trusty helper working the tap, and once
water came out of the expansion pipe then the top end of the system was
clear of air and crud. Probably best to put a bucket in the (empty) tank
under the expansion pipe to save having to siphon the water out again.

I describd this correctly (I think) a few months back - will have to Google
back and find out.

Thinking further, if you attached the hose to the expansion pipe with the
down pipe still connected, then this would force water round the system and
water should come up the down pipe.
This again would clear air and crud out of the top end of the system.
However ISTR my expansion pipe is 22mm so would need some adapting to take a
hose pipe (which just fits 15mm).

Apologies to the OP for my senior moment :-(

Cheers
Dave R