I'm specifying a gas/solar central heating system. It is an old house so, although the wall insulation will be improved, I will still have radiators and probably two wet UFH (bathrooms) zones. The house is sometimes partially occupied so I am keen to build in intelligent controls, so that for example, a home office could be heated on its own during the day.

I found those Sauter 24V TRV head replacements. As part of the renovation the house could be re-plumbed to have two or three zones and those valves on some of the rads.

What I've found most domestic CH controls aren't really geared up to many zone programming. Then I stumbled into HA...

The only HA-like stuff I have now is a LinkStation Pro LS-XHL NAS which has been "opened" to run NFS and SqueezeCenter. It's quick (1.2GHz I think) and fairly low power (~10W when idle) and could easily run another webserver.

I can see there are a number of competing products but have been getting swamped! Idratek seemed an interesting starting point but I don't want anything that needs a Windows PC running 24/7. Clipsal seems to have quite a large following and active forums.

I suppose what would be ideal would be:
  • a unit that I could wire the rad/zone valves and boiler to (which probably will be OpenTherm compatible), and that had an ethernet connection,
  • a 1-wire system controller, again ethernet connected (which I've seen), that has thermometers in each/key rooms,
  • some (Linux) software that ran all the time on the LinkStation and could control components.

Then I could just use a browser, e.g. on a hacked O2 Joggler, to interact with the heating.

Of course once the HA infrastructure were there I might like to do more later, but at the moment the purpose is just to create a more efficient heating system.

My observations so far:
  • I like the idea of the pink C-Bus CAT5 cable so that you can run signal and mains cables in the same conduit
  • Both Idranet and C-Bus are distributed systems than can run without a central controller (though with what intelligence - possibly not enough for CH control without having quite intelligent room thermostats?)
  • Both Idranet and C-Bus can be wired in topologies of star, daisy chain, or a combination of both.

Therefore my initial thoughts are:
  • run a single 1mm T+E from each rad to a central point (to use for 24V)
  • have 24V rad valves & single power supply at the central point. The control system would use relays to switch the 24V, though would also need to switch 240V for zone valves
  • run a pink C-Bus cable from room to room (at the rad or light switch?)

My main priority is to choose something now that would then be compatible with other HA stuff later (which rules out some of the heating only products like HouseHeat I think).

Sorry for the very long post! Any thoughts or comments would be very welcome :-)