It happens that John Rumm formulated :
Did he flush the system carefully? (Like most HE boilers, they like a nice
clean primary system).

No, he was happy to accept that my system was reasonably clean, but I
had filled and flushed twice anyway. He didn't sound convinced that all
the obsession with flushing on a relatively clean well looked after
system was necessary.

Rather than the filter he had originally said he would fit, he fitted a
Fernox Omega TF1, because it could be installed in an horizontal or
vertical pipe. Horizontal suited the layout above the boiler better.

The TF1 also seems to be more robustly built/ all brass than the
Magnaclean he had originally suggested. It also seems a bit easier to
service it too. I gave it a clean after a few hours running - it had
managed to prevent some Plumbers Mait getting through to the boiler and
a tiny trace of magnetite.

After the old Ideal was out on my drive, out of curiosity I gave that a
good forward and reverse flush through, to see what might come out of
it. There was nothing at all, clean as a whistle.

Whether due to the new boiler or the TRV's I have fitted, the whole
house seems to be much more evenly heated. I never bothered originally
to balance the rads and the poorly insulated and extended utility room,
with a too small rad, it always suffered from being less than adequate
heating. Probably due to other TRV's being satisfied, it now gets much
more heat pumped through to there.

I have ordered up a pipe stat, to fit on the flow. Intention is to set
that to 60C wired in series with the room stat, to limit the call for
the boiler to a 60C flow, so it stays condensing most of the time. I
have had to set the main boiler stat to 75C, in order to get the HW
tank up to a sensible temperature. A luke warm 55 to 60C is no use to
us and the boiler only has the single flow temperature setting. With
that fitted, the boiler should stay in the efficient condensing
temperature range when just supplying CH, but be able to run hotter
when water heating is called for.