Re: UFH Control & CBus

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

I have found the C-Bus internal temp sensor is not really very suitable
for temperature control of a room - it has a very wide hysteresis and
only reports in 1 degree increments AFAIK so you rooms will have quite
wide temperature fluctuations - 2 degrees at least. In fact mine varies
by as much as 4 degrees due to overshoots caused by the heat retention
in the heavy old cast iron radiators using standard ON/OFF zone valves.
I am firmly convinced proportional valves/feedback is the right way to
do this, but I haven't done it yet.  At UKHA 2003 , almost  two years
ago Graham C from Clipsal said that they were about to release room
thermostats which would be a new product with much better suitability
for local heating control and possibly local setpoint adjustments - but
I haven't seen anything since :-(

If you are prepared to roll your own then the Dallas sensors are much
more sensitive and very tiny -(but we could do with a nice mounting
option). Using something like Justins TOM10 board and either a direct
serial connection, Ethernet via an MSS100, or xAP / xPL conduits both of
which are freely available there are lots of options here. The board
handles 10 remote temperature sensors and the cable runs can be quite long.

Kevin



markttay wrote:

>I was hoping to use SmartKontrols for UFH control in the house I am
>building but was put off by the cost which came out around £760
>per
>zone/room for design and supply.
>
>While I appreciate that it is far less sophisticated, it struck me
>that I could have programmable temperture control using the Cbus
>Indoor Temperature sensors and some more relays to switch the UFH
>manifold actuators. This would work out around £140 per room/zone
>on
>the same basis, and while the whole lot would have to be programmed,
>I assume there would be the opportunity to do some integration with
>other Clipsal input units such as PIR occupancy sensors etc.
>
>I do think that the CBus sensor is pretty ugly and nowehere near as
>descrete as SmartKontrols, but it is a much cheaper (weird saying
>that about any CBus stuff!) or so it seems.
>
>I am a novice in this area and know that heating control has been
>debated at length on this forum, but if anyone has used CBus for
>this purpose or can suggest a better alternative, I would be very
>interested. I am not keen on going for a home-brew option as I am
>not competent enough to install and maintain it and want to stick
>with standard solutions.
>
>Thanks
>
>