Re: Real HA - central heating control by the radiator

[ian.bird@xxxxxxxxxxxxxx]

Hi David

I was thinking about this and I liked Kevin's suggestion of just switching
the 10v feed on or off giving me effectively the same as the on off unit.
As you say though this opens up potential for future expansion.

>From my point of view I have to build something that will work by next
winter which is not a whole lot of time away taking into account having to
go to work too.

My initial thoughts are:
1) Local power supply to power the unit and the valve (no idea how much 24
volt supplies are?). May go with POE and a 24volt network so 2 times Cat5
to each zone.
2) Ethernet connected local units to switch the valve. Will also take a
minimum of two temperature readings. One would be for the room temperature
in the chosen location and the other would be the radiator temperature. In
reality there would probably be the ability to have more room temp units.
3) Mark 1 units would only switch on and off
4) Communication protocol is open but I would think xAP would be a good
choice. This would also fit in with some graphic displays I am designing.
5) Initially I would probably use HomeVision to control the radiators (it
does the heating now) but I would aim to add additional brains in a home
made control unit. Ultimately I would not only want radiator by radiator
control but also control from every room in the house with customisable
abilities. For example the kids rooms would only be able to control that
room whereas the main bedroom would not have any limits. I plan password
protection on these too so no kids sneaking into mum and dads room for
dastardly deeds ;-).There would also need to be a master control so the
kids don't just set it on all the time. Lots of permutations to confuse me
horribly. Of course it would be nice to record what was on when and where
it was activated from which I would include in my home made control unit.
This could then be queried from a PC and printed or whatever.

Boiler cycling would be controlled in software somehow. Long way away from
that though.

The beauty of this approach is I can phase the system in as time allows and
debug on route. I would also try and make the Ethernet part of the unit
separate from the switching part as this will keep costs down when I change
the spec. Just have a plug and socket type of connector. Also, since size
is not a big issue I can design for 'PCB comfort' rather than for the
smallest size as I have been doing of late. Roll on that PCB autorouter ;-)

I would guess 8 units would be my ideal. This would give me one spare and
leave one Radiator without a valve so heat can always be dissipated in the
case of something going wrong.

Ian







"David Gumbrell"
<david.gumbrell@g        To:       ukha_d@xxxxxxx
mail.com>                cc:       (bcc: Ian Bird/CV/Novartis)
Sent by:                 Subject:  Re: [ukha_d] Real HA - central heating
control by the radiator
ukha_d@yahoogroup
s.com


28/03/2006 01:47
Please respond to
ukha_d






Hi Kevin,

If you go for a bulk buy, I'd be interested in 6-7 of the proportional
ones.

Ian: I think proportional will give you much greater scope for decent
control schemes, although at a cost, obviously. I suspect On/Off is
going to create more boiler cycling.

Cheers,

Dave

On 3/27/06, Kevin Hawkins <lists@xxxxxxx> wrote:
> ian.bird@xxxxxxx wrote:
> > Hi Kevin
> >
> > Where did you get the price from? Also any idea how much the
other
parts
> > needed are? I will need 7 at the end of the day plus maybe a
spare
head.
> >
> That was just a Google using the part number - it pulled up a PDF
pricelist
>
> Danfoss Gesmbh Presiliste April 2005 Warmetechnik  www.danfoss.at
> > A 0 to 10 volt control voltage doesn't sound too hard although
for home
use
> > I suspect the on/off ones would be just fine.
> >
> I'd prefer the proportional ones I think - at worst case I can just
> drive them with ONOFF 10V I guess if that all goes pear shaped.
>
> Kevin