We had a modest extension built a few years ago, but now no longer get
any heat from either of two radiators installed.
I've checked the pipework - there are two tees off the underfloor 22mm
flow and return to 15mm copper, which then connects to grey plastic
with push fit(?) connectors. The pipes disappear from the house
through an outer wall underground, and eventually must appear somewhere
within the concrete floor of the extension. Hot and cold water to
supply the utility room in the extension are connected in much the same
way. These both are fine.
I've just drained and flushed the main heating system, and while
drained tried to flush through the extension pipework. I dissembled
the copper pipes from the two compression tees, and connected our
garden hose to one, with a pipe into the kitchen sink from the other.
With mains pressure applied, there was only a tiny trickle out of the
other pipe - even when both radiator valves were fully open.
Has anyone any idea what has happenned? I would have thought the
plastic pipe underground would have been wrapped in insulation, then
encased in concrete - but it seems as though one or other of the two
pipes has become constricted in some way. How do the copper to plastic
connectors work? The seem as though they are push fit.

"tango sierra" wrote

We had a modest extension built a few years ago, but now no longer get
any heat from either of two radiators installed.
I've just drained and flushed the main heating system, and while
drained tried to flush through the extension pipework. I dissembled
the copper pipes from the two compression tees, and connected our
garden hose to one, with a pipe into the kitchen sink from the other.
With mains pressure applied, there was only a tiny trickle out of the
other pipe - even when both radiator valves were fully open.
Has anyone any idea what has happenned?

Had a similar issue myself. Affected flow side piping only.
Radiators bled OK but no heat to speak of.
Depends how old your system is and how its been piped/maintained - but my
problem was magnetite.
This I believe is what sludge can turn into in certain circumstances almost
like crystalline coal particles.

Anyway this had made its way down the plastic piping and collected and
blocked behind the rad valve itself.
Remedy was to take off rad, open valve and "broggle" down through the valve
into the pipe with a thin tie-wrap.
Obviously, if this is the blockage location, water and crap will spurt out
of the valve at this point!
A few repeats of this, turning the valve off quick when flow started,
managed to clear the block enough for a flushing operation to be successful.

HTH

Phil

TheScullster wrote:
"tango sierra" wrote

We had a modest extension built a few years ago, but now no longer get
any heat from either of two radiators installed.
I've just drained and flushed the main heating system, and while
drained tried to flush through the extension pipework. I dissembled
the copper pipes from the two compression tees, and connected our
garden hose to one, with a pipe into the kitchen sink from the other.
With mains pressure applied, there was only a tiny trickle out of the
other pipe - even when both radiator valves were fully open.
Has anyone any idea what has happenned?

Had a similar issue myself. Affected flow side piping only.
Radiators bled OK but no heat to speak of.
Depends how old your system is and how its been piped/maintained - but my
problem was magnetite.
This I believe is what sludge can turn into in certain circumstances almost
like crystalline coal particles.

Anyway this had made its way down the plastic piping and collected and
blocked behind the rad valve itself.
Remedy was to take off rad, open valve and "broggle" down through the valve
into the pipe with a thin tie-wrap.
Obviously, if this is the blockage location, water and crap will spurt out
of the valve at this point!
A few repeats of this, turning the valve off quick when flow started,
managed to clear the block enough for a flushing operation to be successful.

HTH

Phil

Thanks for this Phil.

The system was filled with Fernox some years ago. I've just removed
one radiator in the extension, and intend exploring the pipework with a
long wire at the weekend. You're right - I've established that the
blockage is only on one of the two pipes - but don't know which one is
the flow, and which is the return. Fingers crossed!

Tim.