"Doctor Drivel" wrote in message
...

That gets rid of the problem of getting ducting from one floor to another.
One in the loft and one maybe under the stairs downstairs. But again
Unico have solved much of that problem with small tube ducting.

As you seem to be obsessed with water inside pipes, you could have a
boiler as the heat source. A air handler with copper heat battery in the
loft for upstairs and one downstairs. Just 22mm pipe running to each and
no ducting between floors. The air handling units are just big Myson
heaters with ducting coming off them.

Using a boiler and air handlers with copper heater batteries means that by
installing bronze pumps all ferrous is taken out of the system. No sludge
that plagues rad system then. Rads are sludge collectors and the efficiency
drops in time an dten the corrosion, etc.