Can I connect radiator return to ANY point?

[jonnyplatt]

I want to add 2 new radiators to the central heating system. It's 22mm piped from boiler to pump then motorised valve splits the feed to either the hot water or rads. Lots of 10mm pipes then come off the 22mm main flow and return pipes feeding each existing radiator.

In order to add 2 more rads I'm proposing to tee into these 22mm flow and return pipes with a 15mm pipe feeding the 2 new rads (10mm pipework will be used where the 15mm splits nearer the rads). I'll tee in on the pumped side (after the pump and motorised valve) just before the 'octopus' end (LHS of photo). I was going to tee into the return side near the return 'octopus' (RHS of photo) but as this (presumably) just goes back to the boiler could I tee in near the boiler which is closer to the new rads positions?

[stoneyboy]

jonnyplatt,
I don't see any problems with your proposal except when it comes to re-balancing the system.
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