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Re: Re: Controlling Heating
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found this
check out the intelligent thermostats
?
looks great
----- Original Message -----
Sent: Friday, April 12, 2002 2:02
PM
Subject: RE: [ukha_d] Re: Controlling
Heating
Thermostats and motorised valves work quite well
but
tend to oscillate a little due to hysteresis. The effect is that the room
tends to warm and cool alternately - if you have heavy radiators egg cast
iron
then the effect is worse as the radiators continue to pour out heat after
the
flow is turned off.
A way around this is called proportional control
-
this is effectively not using just valves that are open or closed but ones
that can be partially open. The motorised heads that go on valves can also
be
supplied as proportional versions. Indeed you can replace the heads with
proportional ones and keep the same valves They operate by opening
proportionally (that word again) to the voltage applied so on say a 24v
version with 12V applied it would be half open. Accompanying these you
also use proportional thermostats that give out a voltage the varies
depending on how far away from the setpoint you are - egg set to 21degrees
and
reading 20 gives say 3 volts out but if the temp dropped to 19 it might
give
say 10V out. At setpoint it falls to near zero. This gives a system that
settles to a point where the flow through the radiators is reduced to the
volume that is required to maintain the temperature in the room - it is
more
expensive and complex but produces a better result. You can simulate
proportional thermostats using say the Dallas sensors and some programming
in
a HA controller to output through a D/A converter. HomeVision can do this
for
example. Getting the levels (ramp rates) right is really a case of
trial
and error, - or that's how I did it.
Kevin
Nik,
I haven't done
any of this stuff, but I'm sure there are motorised valves
that use
either 12V or 24V. - I guess in that case you can use a single LV
cable
for both power and signal....
Check out the Honeywell Smartfit stuff
on www.comfort.org.uk as well...
Paul G
>From:
"Nikola Kasic" <nikola@xxxxxxx>
>Reply-To:
ukha_d@xxxxxxx>To:
<ukha_d@xxxxxxx>
>Subject: RE: [ukha_d] Re: Controlling
Heating
>Date: Fri, 12 Apr 2002 11:09:30
+0100
>
>Stuart,
>One general question:
>If I want
to control central heating in each room individually, each
>radiator
has to have some kind of valve which is operated remotely.
>I asume
that they will need power, so each radiator will need two
cables,
>one
for power and one for control signal.
>Is there any way to reduce
that
cabling, so we don't need to rewire house?
>Also, putting power
socket
into bathroom is against regulations, I
think.
>Nik
> -----Original
Message-----
> From: stuartgrimshaw
[mailto:stuart@xxxxxxx]
> Sent: 12 April 2002
00:51
> To: ukha_d@xxxxxxx>
Subject: [ukha_d] Re: Controlling
Heating
>
>
> Hi
Marc,
>
> I just got my connection back after a
month, and I was scanning the
> stuff I missed, and I
noticed no-one replied to your mail, that's
> the problem
on a list where the signal to noise ratio is so
low.
>
> Anyway ... I beleive what you want to do
is
use a Universal Module
> (http://www.laser.com/?laserlink=SGUM506)
unit to drive a larger
> relay to do the
switching.
>
> I know there are a couple of people
use this or a similar method,
> and Keith D should be
able
to give you more precise advice.
>
> Also, have a
look at "How do I automate...." in the FAQ, there's a
>
link on there to Keiths site and info on how he did
something
> similar.
>
> --- In
ukha_d@y..., "Marc Mosthav" <marc@m...> wrote:
>
> Hi all,
> >
> > I would like
to control my heating from my HA computer. I do have
> a
Dallas temp. sensor and would like to control the connection
which
> is usually connected to the thermostat. My
problem
is that the
> b****rd thing is 30VAC / 1A and that all
the
X10 relay devices are
> rated at xVDC. Am I thinking the
wrong way 'round, am I stupid or do
> I have to do
something totally different???
> > BTW nobody answered
my question about all my broken TM13's so I
> assume that
they work fine for everybody else? Mine are just
>
switched off and are not responding to anything.
> >
Any help on either question would be greatly
apreciated.
>
>
> >
Marc
>
>
>
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