On 06/10/2019 15:44, Andy Bennet wrote:
On 06/10/2019 13:00, ARW wrote:
The water to the header tank was turned off and the system drained down.

Swapped the mid position vale and it will now not fill back up.

The odd thing is the header tank did not drain off - it was still full
when I went to turn the water on.


Suggestions?

--

Adam

Congealed sludge in the downfeed from the header? I had that a few years
ago on a bend situated behind the hot water tank. Happy days.

especially since the blockage might have suddenly released when the
valve was removed :-)