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This
sounds very similar to a heating system I install called Seachange or now
know
as smartkontrols. I am going to set up something similar at home
using
homevision. Rather than using rad valves as described below I am going to
use
weather compensation in than I will measure both flow and outside
temperature
and reduce the flow temperature from the boiler to the rads according
to
external temp. This would have a similar effect as below that reducing flow
temp
to radiators reduces the over shoot of temp to the room. As I use TRV
valves right now I will also measure return temp as this will fluctuate
according to how much heat is radiated from the radiators. Also I get
a
good indication of how quickly the house heats and how much return water
measures. This will help in stage 2 of boiler control to regulate the flow
temp.
Say outside is 15 I will want a flow temp of around 40 instead of 70 which
it
runs at now. To reduce this for now I will time proportion the boiler. i.e.
how
long its on and how long its off. This will then give a desired flow temp
output. My boiler demand will be measured from 4 points around the house
and
this demand must be met in a time that I will specified. I am hoping to get
this
figure from a variable that will varied according to outside temp and how
long
normally my heating system can heat the house from certain points.
Hopefully
this will be self learning but god knows where to start with that logic but
im
up for a challenge. Last stage is optimum start and stop. IE if I say I
want 20
degs in the morning at 6am the system will learn what time to start to
achieve
this. Also if I say to switch off or go to fabric protection setting at say
11
and the boiler has been off since say 9 the system will shut off early as
those
quick on offs like you get now cost money and significant problems
heating
pipe work up for short times. I love the idea of each rad having its
own
variable actuator but not in this house as I intend to move soon. Defiantly
next
house!!
Obviously you can get all of the above and more if
you
have multiple boilers and duty standby pumps etc if you buy seachange or
smartkontrols but where is the fun in that??
Anyone
else done this or interested drop me an email.
Very interesting Kevin
How did you do the D/A from homevision
?
Frank Mc
----- Original Message -----
Sent: Friday, April 12, 2002 11:02
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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