Phil L wrote:

My main question is about the radiators - they're quite old, at least 15
years, but the plumbing to them and to the existing boiler is only about 8,
my idea is to leave everything in place and just swap the boiler,
brilliant! - except....over the past few years, what with all the topping up
etc, there has been no inhibitor in the system and the water now is akin to
crude oil.
I took off all the downstairs rads last year and took them into the back
garden for a spot of hosepipe therapy, and the patio is still stained black,
so my question is this; should I take off all the rads and flush them out
manually (this is not a problem, even with the upstairs ones), or should I
use some other method of flushing out the system, which will also clean out
the pipework inbetween the rads, if so which / what, and how much? - bearing
in mind that I have just forked out my last £240 on a new boiler.

I would start by adding a chemical cleaner now and leaving it running
with the old boiler for at least a couple of days - preferably a week or
more.

I assume you are going for a sealed system rather than vented?

If so, then since you have flushed the rads not that long ago, you can
probably get away with doing them in situ this time. If you have not got
a decent drain point you need to add one (a hard piped one that has a
service valve on the inside, and a pipe that goes through a wall to a
gully outside is the easiest to use). To flush, turn off all rads but
one. Open the drain valve, and open the filling loop so you are
directing the full mains flow through the pipes and that one rad. Let it
flow until it is running clear. Once that one is, open the valves on the
next rad, and then go back and close them on the first (by doing it in
this way you can just leave the filling loop tap open). Rinse and repeat
until you have run out of rads.




--
Cheers,

John.

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