Air Conditioning - Central air controlled by 2 thermostats?

Hi,

I have a central air unit that cools 2 rooms. The rooms are completely separated i.e no open airflow between the two rooms. The thermostat is located in one of the rooms. I would like to have two separate thermostats, one in each room so that if either thermostat calls for cooling, the unit will operate, even if it means overcooling the other room.

The thermostat is only for cooling - the heating in both rooms is controlled by other thermostats. Is it possible to add another thermostat in parallel with the existing one?

Thanks
Ken

What you need there is called zoning.

In your particular case: 2 thermostats, 2 zone dampers, a bypass duct, and a zone controller such as Honeywell's EMM-3.

The t-stats communicate with the EMM-3, and only the EMM-3 will do the talking to the central A.C. unit.

That would probably work but have you tried simply running the blower full time? If you have a properly sized seperate return for each room the temps should even out nicely, if the supply air is evenly balanced between the two rooms that should work? If you need a radically different temp in each room then you are probably looking at a VAV box and possibly a bypass duct. Lots of options you might want to look at some of the honeywell products. How big are your rooms and how much air volume and tons of cooling are you sending them? Even air distribution and return would probably be the simpler solution unless you have some type of fluctuating heat source that is causing the problem and or a need for radical room to room temp differences.

Thanks for the reply guys, but you're giving me more of an answer than I'm looking for. Probably because I need to be more specific with my question.

This is in a commercial building. The two rooms are about 250 sqft each. I believe it is a 3 ton unit with one air handler.

My problem is that each room is occupied by a different tenant. The room with the t-stat is not occupied very often, the room without the t-stat is occupied more frequently.

Also, this is in coastal Maine. So the a/c won't be run very often. I know what I want to do is not an optimally efficient system, nor will it provide very professional results. That's OK. I just need the simplest, quickest, easiest, cheapest way to give both tenants a way to kick on the a/c. Again, if it causes one room to be overcooled, that's OK, we'll deal with it.

So once again, can I put a second t-stat in parallel with the first one?

Thanks
Ken

YES, or relocate the existing stat. You also turn off the existing stat at the subbase sw. if it has a subbase, or leave it set for 75-80*.