Re: multi-zone central heating

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

Ake Hedman wrote:

>This is very interesting to here. Controlling the heat system to make
it
>more comfortable and economic is one my biggest interest as it comes to
>SOHO control  Mostly because a colleague to me that does research in
the
>area say it is impossible to build an adaptive self contaned  system
for
>this type of control situations without getting big oscillations. It
>must be possible IMHO.  As soon as the infrastructure for VSCP is in
>place I will try this out.
>
>I think one should look at the change in temperature instead of just
>dumb set-points with some hysteresis and close the valve when you
>predict that the set-temp should be reached.
>
I have actually tried this Ake . What I have found though is that the
radiator heats very quickly. Maybe my flow temp is too high or the flow
rate too fast but if I open the valve for even just a few seconds then
the radiator achieves a really hot temperature and it takes some
considerable while to dissipate this, causing the oscillations and the
hysteresis.   So instead of waiting for a temp to be satisfied I
calculated how long I expected it would take for it to be reached and
played with different valve 'open' times to just achieve this (without
an overshoot), it certainly is better in that you are not removing the
feed to the heat source (which still has stored capacity) at the point
that  it has already reached temperature.  But I feel the right way is
to be able to set the radiator to a constant temperature that is in
'balance' with heat from the circulating water and the heat it
dissipates to keep the room at a steady temperature.. hence you would
have warm radiators at a  semi constant temp.  I think the best way to
do this is with some form of proportional valve or similar - and playing
with the 'feedback' system will be reasonably fun I think. So I was
looking for a DIY approach - at least to play - before I get so
frustrated that I call SK in , which I might consider anyway on a
smaller '2 room only' approach if thats possible.

PS Any news on VSCP / xAP ??

K