Velvet wrote (and wrote and wrote, then snipped it all).
I've googled, read the faq's, but I still have some questions.


Aha!

I've experimented, having found a control box on top of the pump marked
up with I, II, and III. No prizes for guessing which one it was set
on...

It's now set to the other end of the scale. Rads are now warming up
more in the manner I would expect (ie, I can finally be sure the one in
the hall really IS the furthest from the boiler). All LSVs and TRVs
fully open, boiler's set to max, and I'm waiting for it to get up to
temp before I shut off all the trv's and work out how far I can close
the bathroom (non trv) rad before the boiler complains. That'll give
me a baseline for that radiator, and I should (hopefully!) then be able
to throttle back all the others (apart from the index, which is the
hall) to what's needed for them to be a little more balanced.
There's really very marked difference in the flow reaching the hall rad
(water has to go up to the bathroom from the boiler, across to the
front of the house via all the upstairs rads, and then down the wall,
to the hall rad by the front door). I'm thinking I may find the pump
speed needs to be set for the middle, not sure if the up - across -
down - up - back - down to boiler again means it's still only once the
head or if it's twice...

Velvet