RE: HA control of your Air Con unit

["Phil Harris" <phillip.harris1@xxxxxxx>]

Remove the user buttons?

I was just going to set-and-forget mine to "cool" and 16deg and
let HV turn
the sucker on and off!

Phil

> -----Original Message-----
> From: Keith Doxey [mailto:ukha@xxxxxxx]
> Sent: 05 July 2001 11:00
> To: ukha_d
> Subject: RE: [ukha_d] HA control of your Air Con unit
>
>
> Interfacing to a device such as the Aircon or a Satellite
> receiver that has
> a low voltage control panel is a Piece of P***.
>
> You use a multimeter to detect with side of the switch is more
> positive than
> the other when the switch is open. Typically you will see a reading of
3-5
> volts.
>
> All you  have to do is wire the Transistor of an Opto-Isolator across
the
> contacts with the correct polarity. You then connect the LED of the
> opto-isolator t  your HA controller via a suitable resistor. Lighting
the
> LED simulates pressing the button.
>
> You MUST use and Opto-Isolator for safety but these come in
> Single, Dual or
> Quad packages and are cheap.
>
> No feedback is NOT a good idea.
> For example the "Mode" button on the Aircon cycles round
Fan,Cool,Heat. If
> someone has pressed the button to turn Cooling on and HV presses
> the button
> you will turn the cooling off and heating on. It probably wouldnt heat
the
> house as the room temp would be higher than the temp setting,
> unless you has
> a powercut whereby the heat setting would have defaulted t  26C.
>
> As you say, you can get to a "Known State" by using an AM to
> reset the unit
> but you would have to do that EVERY time you wanted t  adjust it
> just incase
> someone had pressed a button :-(
>
> Keith
>
> -----Original Message-----
> From: Ian Bird [mailto:I.Bird@xxxxxxx]
> Sent: 05 July 2001 10:17
> To: Ukha_d
> Subject: [ukha_d] HA control of your Air Con unit
>
>
> Having read the previous post about automating the Homebase A/C
> units I was
> just wondering..
>
> I have HomeVision but am currently using most of the relay output
> ports for
> my watering valves. I know Port C can be configured for output
> but can only
> drive ttl, cmos, leds or similar. I don't see any reason why this
> could not
> drive a transistor and that in turn either simulate the switch or
> a relay to
> simulate the switch (depending on the requirements). That would give
HV
> control over the unit with manual override available (but no
feedback).
>
> This is something I might look into soon(ish) as it would be dead
useful.
> The lack of feedback would not bother me particularly as I could
always
> reset the unit using an appliance module e.g. prior to turning it on.
>
> If you don't have HV then back t  the drawing board. If this and
another
> interface could be designed into the same unit then let me know and
we'll
> think about it.
>
> Phil - have you taken off the panel or whatever yet (defeated the anti
> tamper screws)?
>
> Ian
>
>
>
>
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> http://www.automatedhome.co.uk
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>
>
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>
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> http://www.automatedhome.co.uk
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