"Neil Jones" wrote in message
m...
"Set Square" ...
In an earlier contribution to this discussion,
Neil Jones wrote:


I have gas fired central heating with a non-modulating conventional
cast iron boiler which is rated at about double the worst-case heat
loss for the house. I have a programmable room stat, with TRVs on 10
radiators and one bypass.

How much would it cost to add individual time/temp control to the
system with a view to increasing efficiency without the disruption
of
moving or reconfiguring pipework?

If you recall, I mentioned that I had been looking at the CM67z and
HR80 solution yesterday becasue it appeared to do what I wanted,
although at the price indicated I would want more - interfaces to
house control system, that kind of thing.


I think that if I were to upgrade my system -
which is similar to yours except that I haven't
got any TRVs - I would probably fit a 2-port
zone valve in the feed to each rad, and
have each of these controlled by a
programmable room stat. [Ok, I would need
10 stats, but they could be a lot less exotic
than a CM67z]. Installing zone valves would not
necessitate converting to a manifold system
(contrary to IMM's inference)

A manifold is by far the best method all around, although not necessary.

as long as you can get at the feed pipe
to each rad in some suitable location.
Bringing them all together in a
central point would simplify wiring up all the
volt-free contacts on the zone valves to
control the boiler - but is by no
means essential. In my case, at any rate,
all the zone valves could be under
the upstairs floorboards, and the only
exposed wiring would be that
going to each room stat - which I would
cover with small section white square
trunking until the room is next decorated,
when I would chase it into the plaster.

In your case you could use CM67RFs and no wiring and re-decorating.