"Doctor Drivel" wrote:

The inserts on plastic pipe reduce the 15mm to 12mm. This may contribute.

Not sure if inserts have been used!
Tees are push fit Hep2o in main 15mm runs rather than compression fittings.
How are these removed? I have heard mention of sliding collars but can't
see them on this type of fitting!

Even if the pipes are too small for the heat load you should still be
getting flow to all the rads. If all downstairs rads are off does all
upstairs work OK?

I will try this. Not sure if I've tried this before or not!
If flow is still not adequate, is it a mains size increase? If so, how much
do I need to upgrade and is plastic the way to go?


Have you increased the pump speed?

Reluctant to do this as I have had pump over problems in the past!
Is it likely that the two issues are related?


Thanks for help

Phil