newshound Wrote in message:
On 04/03/2018 17:54, TheChief wrote:
Hi Guys

I am having problems with piping to radiators which has been run
in plastic pipe.
I suspect that the poor performance of the rads is partly down to
15mm pipe being used over a fair length and teed to two rads.
There is also some crud floating around which is blocking the
feed pipe, or restricting the flow.
So I was looking at increasing two 15mm runs to 22mm to help the
flow and decrease the likelihood of future blockages.

Contemplating this leads to the type and reliability of different
joint types. The current 15mm plastic runs connect to the
original 22mm copper mains via copper reducing tees/stub pipes
and Hep20 push fit couplers. I have not had any problems with
these.

What are the group's current thoughts on push fit Vs compression
on plastic pipe, particularly 22mm?
Some recent posts suggest that Hep20 fittings are not as reliable
as previously.

Thanks

Phil

Assuming it is a pumped system rather than natural circulation, and a
normal sized house without "Stately Home" run lengths. I'd expect 15 mm
to be plenty, and 22 mm overkill. Perhaps you could tell us the size (or
BTU rating) of the radiators, and the length of the run, then someone
could give more definitive advice. Blockages are possible but as another
poster said, has the system been balanced?


Thanks guys

I am pretty sure the 15mm plastic runs away from the mains
are
susceptible to catching the crud. The fact that the tees feeding
them point downward at about 45 degrees makes them a crap trap.
Plus, the plastic pipes are not clipped in place but laid
undulating across the ground floor ceiling between first floor
joists.

All other rads in the house heat up respectably. If I limit
heating to upstairs rads only and throttle down all others I can
get some flow to our bedroom rad. But the towel rail in our en
suite is not warming at all.

The pipe layout. From the two principle 22mm copper mains, one
plastic 15mm flow and return pipe each run approx 5m. They then
both tee 4m toward a small double convector rad in one direction
and 2.5m in the other direction to a large towel rail. The rad
is just about warming when thermostats have all closed elsewhere,
but the towel rail does not.

If everything was A1 I believe that 15mm would probably just about
work here. But knowing the likelihood of crud being deposited, I
am inclined to increase the 5m runs to 22mm and blow out the
remaining 15mm runs and see how long that will last. I did run
cleaner numerous times around the system when I took the place on
and have run a MagnaClean filter for the last 12
years.

Phil

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