T i m wrote:
On Thu, 25 Jan 2018 15:30:52 +0000 (GMT), Tim+
wrote:

snip

So, it's clearly not the rubber swelling as I imagined but a build
up of either corrosion of the fitting itself or deposition of
crud in the pipework perhaps exacerbated by small internal bore
of the connectors. (About 6mm).

It all seems strange to me as the last system I worked on was my Mums
and that's mostly an ex gravity system and the pipe sizes are huge!
;-)

Anyhow, as this is the second time I've seen this happen with
these flexible hoses in CH systems I think that it's a strong
indication never to use them.

Or anything that substantially reduces or restricts the flow,
especially where it's not easy to access / service.

Actually, I think its the flow restriction and probable inadequate
corrosion inhibitor that combine to lead to the blockages. Ive probably
been a little unfair to the hoses in that nothing appears to have gone
wrong with the rubber and theres no corrosion of any hose components that
I can see.

When you have a 15mm pipe that is constricted to 6mm, then opens up to
about 12mm before going through another 6mm constriction, I think you
probably have the perfect device to trap any circulating crud.


The radiator is now toasty and warm for the first time in years.

Excellent.

A very satisfying hour's work.

It's lovely when a plan comes together eh. ;-)

Indeed. ;-)

Tim

--
Please don't feed the trolls