Roger Mills wrote:
In an earlier contribution to this discussion,
Dave Osborne wrote:

Well, I'd be willing to bet that there are many millions of systems
out there wired to a classic Sundial plan. Mine is, for one... :-)

However, I'm quite happy to do additional drawings for more modern
installation arrangements.


From my limited reading, the following ideas come to mind:-

1. Wiring diagram for S-plus with one and two extra heating zones.

Yes - good idea.



2. Conventional (i.e. not system) boiler with pump-overrun timer (as
you have suggested above).

Yes - although it's not necessarily a *timer* per se. My boiler simply keeps
the pump running until the output temperature falls below the boiler stat
setting. The important thing is that the pump is controlled by the boiler -
using whatever internal logic it sees fit - rather than being connected in
parallel with the boiler demand.

Understood. "Pump Overrun Facility" from mow on!


3. Classic Y-plan, S-plan with retro-fitted separate pump overrun
timer. (e.g. Broyce Controls M1EDF RS 296-7393).

Maybe(?) but I don't know how common this is. My impression is that if the
boiler *needs* the pump to over-run, it will provide the logic and the
connections.

4. System boiler? I'm kind of assuming that these come with wiring
diagrams and have "wiring centres" built in, so the programmer (if
external) and the thermostats connect directly to the boiler.

I've not got any experience of these, I'm afraid - but I assume they're
simple to wire 'cos most of it will have been done for you.

5. Versions of Y, S and S-plus where there is no central timer, just
programmable thermostats. Is this even a valid way of wiring a system?


Unusual I would have thought - because you would normally have a timer of
some sort (rather than a programmable stat) for the HW.

Good point.

You could, of
course, just have a single channel timer for the HW and connect the
programmable room stat(s) directly to the FCU. That would certainly be
valid.

OK, I might draw this as an example of an S-plus system.

I would need someone or three to commit to assisting with providing
suitable source material (including sketches) and/or reviewing and
commenting on draft drawings as I am no expert on central heating
controls.
Any takers?

DaveyOz

I'm more than willing to review and comment. I'm also happy to have a go at
amending the existing diagrams - preferably electronically - but that
assumes that I have the same tools as those with which you created the
diagrams, which may or may not be the case. What *did* you use?

Well back in August I started in AutoCad cos I'm used to doing drawings
in Autocad, but then I decided to use Adobe Illustrator to tart them up
and make gifs. However, I ended up largely redoing them in Illustrator
and have now dropped AutoCad as an intermediate.


Failing that, I could probably print them, mark them up by hand and then
scan them.

No problem. Whatever works for you.