I've had a quick look at the faqs, with no joy...

I've been called upon by my sister to replace radiators in her house...
a friend of a friend has installed new CH and Rads from a "conventional
radiator pack". Judging from the size of the rads they're about 1/2 the
size that is required for an old, uninsulated house with tall ceilings
(e.g. I've calc'd main-room, 14ftx12ftx12ft needs 2.3kw, rad is probably
1kw [800x600 twin panel]). [separate issue, we're going to insulate the
loft, don't let that detract from the remainder of the story]

So... idea is to replace two largest rooms/radiators with 1400x600
twins, then progressively move the removed radiators through the rest of
the house, replacing next-largest with newly removed radiators.

In principle, I have no real problem with the work involved.... nice
access below the floors, a bit of modification to pipe runs to take,
what for the most of it are wider radiators. BUT... the question is... I
anticipate replacing sections of 22mm pipework to accomodate the larger
rads... online prices suggest a 20% price differential between
solder-ring fittings and end-feed fittings.

As all pipe-work is new (clean copper), given some wire-wool, would the
20% difference between solder-ring fittings, and the price of
solder/flux mean that one or the other is more economical... for someone
who's not soldered pipes in 20 years, is one quicker/easier than the other?

Basically, with 6/7 rads to replace (/move around), what would be the
generally concensus as to the cheapest method (considering I'm buying
all blow-torches etc. from scratch)

Any advice, as it affects the actual cost to my sister, gratefully received.

Regards

Mike Dodd