On Mon, 20 Oct 2003 21:59:06 +0100, Andy Hall wrote:

On Mon, 20 Oct 2003 20:34:09 +0100, Dougie Nisbet
wrote:

[ .. ]

The question: Is it a DIY job? None of my DIY books cover it and my
googling of the NG archives hasn't come up with anything definitive in the
Janet and John guide to flushing your system vein.

Dougie

Yes it is.

You can do a Google Groups search for a method that I have used to
clean and flush successfully, by removing each radiator and taking it
outside for flushing with a mains hose or pressure washer.

This method works especially well if you have a sealed system with a
filling loop connected to the mains water supply. You can flush the
crud out at each radiator valve and clear the pipes very effectively.

Do watch out for sludge and other iron compounds from the radiators.
They are an indellible dye on carpets and furnishings. I use a
plastic bag on each valve tail held on with a rubber band.

I use a pair of new cat litter trays to collect water etc. from each
radiator.

For the TRVs, if they are old enough to be unidirectional, then they
are probably beyond their useful life as well. While you are
cleaning the radiators, I would be inclined to replace them and also
the lockshields.

Once the system is flushed clean, it is a good idea to put in a
chemical flushing agent and running the system hot for a few days.
Then rinse and flush thoroughly.

Finally refill, adding inhibitor. You can add a filling point to do
this by creating a vertical short stub of pipe on the system, closed
off with a cap and then using a funnel to add liquid inhibitor.
Alternatively, you can use a gel inhibitor which comes in mastic gun
cartridges. It is a lot easier and cleaner if you put this stuff
in through a vent before finally filling the system, rather than doing
so against the pressure afterwards.


Thanks - that sounds rather encouraging. The towel rail in the bathroom
has capped tops (what are they called) which I need to investigate but
look very promising in the longer term for adding inhibiter. The bathroom
is on the ground floor so I guess I may have to more or less completely
drain the system when I decide to do this after cleaning.

I'm not sure I'll bother replacing the LSVs and TRVs at the time of
flushing. Partly because of cost although I've not investigated this) but
mostly because I'm not a wild fan of TRVs and recently wired in a Danfoss
TP5 room thermostat
http://www.screwfix.com/app/sfd/cat/...39276&ts=68941 into the
combi which I find much easier and useful. Almost all the rads have the
TRVs fully open and I control temperature and timer with the Danfoss.

I've already read the other posts in this thread and tracked down some of
the archived material and it's raised more questions. I'm not wild about
the idea of removing and flushing 16 rads, but certainly think that doing
the bathroom rail and using it as the access point for flushing the system
is the way for me to go, and I'll see how it goes from there. One problem
I may have of trying to flush water around the CH circuit as my mains
water pressure is pretty poor anyway (lead piping) and I'm not convinced
that it will suffice to give my rads the colonic irrigation they so much
desire. That's another thought - if I shove a hose up the backside of rad
at poor mains pressure, am I not contravening some law about risking
backflow of dirty water into the mains?

Dougie