Hi,
This is a follow-up from "?introduced an airlock...." earlier. I've ended
up draining the system (pumped system). Trouble is it isn't draining the
feed+expansion tank.
I've managed to get most of a 4.7m drain unblocking coil into the pipe.
From the length and feel of the obstruction I think it reached the T
junction with the larger diameter CH return pipe.
The fluid coming from the system looks pretty clear to me so I wouldn't
have thought there is a sludge problem.
None of the plumbers I've phoned are available/have got back to me so I'm
kind of stuck here. Any pearls of wisdom will be appreciated.

Thanks,

Jon

Jon Telfer wrote:

From the length and feel of the obstruction I think it reached the T
junction with the larger diameter CH return pipe.

You can get a plug of limescale at this point, where the cold feed pipe
joins into the central heating system. It's usually the result of a
long-standing small leak, so the system was constantly getting fresh
make-up water containing a fresh dose of limescale.

I'd drain the tank as best I could, then cut out and re-make the Tee
joint. If there's a blockage , it will be apparent when you remove the
Tee.

On Tue, 20 Dec 2005 11:43:56 -0800, Aidan wrote:


Jon Telfer wrote:

From the length and feel of the obstruction I think it reached the T
junction with the larger diameter CH return pipe.

You can get a plug of limescale at this point, where the cold feed pipe
joins into the central heating system. It's usually the result of a
long-standing small leak, so the system was constantly getting fresh
make-up water containing a fresh dose of limescale.

Dunno about the leak bit but I've seen a few systems go this way.

I'd drain the tank as best I could, then cut out and re-make the Tee
joint. If there's a blockage , it will be apparent when you remove the
Tee.

If you can't do that then you can get the system going again by
putting some 'kilrock' or similar limescale remover into the header tank
and leaving it a week or so to dissolve some of the blockage. You'll
probably also need to fill the system up from below by squirting water
into it from a radiator tapping or other convenient point, so that you can
continue to run it. MAKE SURE THE VENT PIPE IS CLEAR! If you fill it so
that water comes out of the vent pipe into the header then you know that
the pipe is clear and the system is full up.

John Stumbles wrote:

If you can't do that then you can get the system going again by
putting some 'kilrock' or similar limescale remover into the header tank
and leaving it a week or so to dissolve some of the blockage.

I wouldn't recommend that because;
a) the descaler will mix & dilute with the system water as soon as a
small hole is dissolved in the blockage, leaving most of the blockage
in place.
b) the descaler is acidic & you really don't want the system water to
be acidic for any significant time. Acidic descalers are used in power
flushing but must be flushed out & the water neutralised asap.