In an earlier contribution to this discussion,
Geronimo W. Christ Esq wrote:


The bathroom radiator is relatively small, but I am considering moving
the TRVs from the radiator in my living room into the bathroom - since
that is where the room stat will be and I understand that the system
will not behave correctly if the room stat fights the TRVs. I may as
well have the living room radiator act as the bypass.

That's fine - but make sure that it can't accidentally be turned off -
preferably by having two lockshield valves on it.

I assume that when the three-port valve is set to do hot water only,
that the cylinder coil will suffice as a bypass.

Yes - as long as any balancing gate valve in the HW circuit isn't turned
down too much. If you can contrive to run the HW heating and CH at
*different* times, you won;t need to do any HW/CH balancing.

The pump overrun thing is a bit tricker than I thought. I had planned
to follow one of your recommendations and run a five-core cable
between the new wiring centre in the hotpress and the boiler
downstairs, but it turns out that there is not conduit all the way
(it goes across a floor as well as between walls) and tracking walls
to install cables is not something I want to get into. Instead I'm
going to re-use the existing three-core cable, which up until now has
supplied mains to the pump, to carry the SL and PL signals to/from
the box, and then provide the boiler with it's own permanent live
from the existing mains connection in downstairs. I guess that should
be easy, just a matter of putting new sleeves on the wires to ensure
that it is clear they are live.

That will work, but it's very bad practice! It is highly recommended to have
the *whole* system powered from a *single* FCU so that anyone working on it
can be *sure* that nothing is live. Powering it from two separate places
will not achieve that - and you may get sued for electrocuting any
unsuspecting BG (or whatever) person who comes to work on it!
--
Cheers,
Roger
______
Please reply to newsgroup.
Reply address IS valid, but is disposable in the event of excessive
spam.