Re: zoned or not zoned?? thermostatic control of multiple spaces

["Lighthouse" <gruntledlark@xxxxxxxxx>]

Marc, this sounds pretty close to what i want to do. not the Aprilaire
thing (way outta my budget), but the other. hope you don't mind helping
me out w/ a few of the details. ok, conventional therms, cat5, serial
wiring, parallel wiring. i'm down w/ all that. i'm not sure about the
24V xformer and the relays. i'm assuming that both of those get
installed in the boiler room along w/ my 7th therm. what kind of
relays?  is the 24v xformr the kind used in doorbell circuits? how do
those fit into the wiring scheme? is it possible for you to sketch this
out for me?

what would be the difference w/ using an AUTO therm instead? as for
discouraging tampering w/ the settings i could possibly camo the therms
inside the casing of a smoke alarm unit.

thanks for the ideas!

Marc_F_Hult wrote:
>
> I would do this with three (or four) communicating Aprilaire 8870
> thermostats and Homeseer software running 24x7 on a low power dedicated PC.
>
> But here's a solution that doesn't use a PC, is extremely reliable,
> presumably inexpensive compared to your energy bill, could be installed
> and(or) serviced by any competent HVAC serviceman, does not look out of the
> ordinary to the occupants, could be incorporated as part of a future zoned
> system, and requires no custom programming, PICs, soldering etc:
>
> 1) Install two inexpensive, conventional thermostats in each apartment in
> no-tamper (fat chance! ;-) enclosures. Thermostat wire is OK but I suggest
> using CAT-5.
>
> 2) You'll need 24VAC transformers and relays as well as the thermostats. You
> might also find a low-cost  thermostat with an AUTO setting (not manual
> Cool-Off-Heat as is conventional) that could replace each pair of
> thermostats.
>
> 3) In each apartment, set one thermostat to COOL with the maximum tolerable
> high temperature (say 76 F), and one to HEAT at the maximum tolerable low
> temperature (say 66 F).
>
> 4) Install a seventh (!) thermostat in a centrally located ('average')
> location that you can access.
>
> 5) Use each of the COOL outputs to energize a relay the controlled contacts
> of which are wired in parallel fashion with the other two. This creates a
> logical OR to force a TOO COLD OVERRIDE.
>
> 6) Use each of the three HEAT outputs to energize a relay the controlled
> contacts of which are wired in parallel fashion with the other two. This
> creates a logical OR to force a TOO HOT OVERRIDE.
>
> 7) Control the boiler with centrally located thermostat's output in series
> with the TOO HOT OVERRIDE (TOO HOT opens circuit) and in parallel with the
> TOO COLD OVERRIDE (TOO COLD completes circuit).
>
> This creates a system in which the building w/should not exceed any of the
> six independently set table TOO COLD OVERRIDE and TOO HOT ORERRIDE limits
> and between those limits is controlled conventionally by the centrally
> located thermostat.
>
> As implied earlier, the fly in the ointment is the concept of a
> "tamper-proof" thermostat enclosure.
>
> ... Marc
> Marc_F_Hult
> www.ECOntrol.org