You will need a fitting with an internal cone for the flexi hose you have there,
The stopcock you have ( Philmac 3G 2833) does both 3/4" Alkathene and 25mm MDPE pipe, no need for adaptors, use the original pipe you cut out...
Here are Osma waste dimensions,
Maybe was used for a standpipe for watering garden/greenhouse and the plugcock was for draining in the winter.
He has an old 3/8"OD 'compression' gate valve, quite common on old oil lines,
the 3/8" pipe with that olive will work in the 10mm union
( the flag...
What you have ther meets the requirements of the building regulations, the waste and the soil pipe centres are the same height on the branch.
Could you do a sketch with approx dimensions of centre of soil stack, centre of WC soil pipe entry and centre of waste for shower from the corner,...
Or just replace what was already there before,...
2 pairs of grips will split it and use the existing nut and olive with your new fitting.
Is the system pipework copper or malleable iron?,
you will also need 'high flow' radiator valves specifically for one pipe systems.
Except out the split in the expansion vessel :rolleyes:.
Some Commercial radiators have 3/4" tappings,
Not cast iron as such, but malleable iron pipe fittings are cast iron fittings,
Using a holesaw, cut the same size out of a 4" X 2", widen the hole in the centre and push it on the core guide rod, once inside the hole that...
Separate names with a comma.