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Re: HA beginner: CH controls - where do I start?!


  • Subject: Re: HA beginner: CH controls - where do I start?!
  • From: "simon_haslam" <simon_haslam@xxxxxxxxxxx>
  • Date: Sat, 17 Apr 2010 13:25:07 -0000


I thought maybe I should approach this from the protocol (which I suppose
is the foundation of any HA system) first. Here are my findings so far:

X10:
- open standard
- one of the oldest & most established/popular HA standards
- mains delivered (primary advantage is it saves having dedicated signal
cables)
- not as sophisticated or as relaible as modern HA protocols

Idranet:
- proprietary protocol
- UK based
- fairly small scale adoption, but plenty of enthusiasts
- low cost components

C-Bus:
- proprietary protocol, though published interface available
- AUS based
- moderately popular
- moderate cost components, not much focus on heating

KNX:
- open standard
- higher end, designed for commercial building management systems(?) though
claims domestic applications
- more expensive components? I haven't found any home equipment vendors
yet.

BACnet:
- looks like another building management protocol but possible quite dated?

1-wire:
- proprietary (but there seem to be lots of competing vendors)
- more of a hobbyists protocol for simple devices - environment monitoring
etc (popular with solar enthusiasts though as it's very cheap to add new
thermometers)
- very low cost
- possibly not robust enough for HA?

The lack of popular open standards in HA has surprised me - if you're
trying to build an HA system to last 10-20 years or so you really want
something that a new owner can get serviced or upgraded... a bit difficult
if there are many competing, but incompatible, products.


My observations:
- 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?)

It sounds like the above would work with both Irdatek and Clipsal systems.
I can't work out how you would integrate an OpenTherm boiler - that would
allow you to minimise the flow temp, i.e. as weather compensation systems
do, to maximise the amount of time the boiler is in condensing mode and
minimise fuel usage.

So that's it so far - feel free to correct errors & ommissions...


Simon
PS. please excuse the typos & grammatical errors in my last post - I
chopped and changed it a bit!
PPS. I've not worked out the difference between this list and the
automatedhome.co.uk forums - would that be a better place to post?



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