Setting for upstairs

[bluefitness]

What temperature should I set my upstairs unit if no one uses that area? I know it is not a good idea to just keep it off completely. At the same time, I do not need it to be at 75 degrees. Let's say the downstairs is set at 75, what should the upstairs be set to for optimum energy efficiency?

[beenthere]

3 to 5° higher.

Depends on how well the first floor unit can maintain its temp with the second floor bing set higher.

[Freezeking2000]

Why not turn it off ?

Just watch the humidity levels if you are in a moist area and run as needed to keep 50% RH.

[DanW13]

IMO it depends on what temp your able to be comfortable at, if you like to seelp in cool temps I would turn the AC downstairs down several degrees and turn the upstairs up several degrees. If your home is sealed properly your AC is not going to run anymore then necessary no matter what emp you set your stat to.

[bluefitness]

The downstairs unit would pull hot air from upstairs. This would cause longer run times on the larger unit. It would also cause humidity problems and possibly short cycling of the unit. I know hot air rises, but the upstairs is wide open to the downstairs (large foyer that extends to the top level ceiling with balcony overlooking). I would also think that there would be heat gain from the uninsulated 2nd story floor.

Those are some of the reason I don't want to just shut it off. I'm looking for utility savings and comfort. Would I save more money by shutting down the upstairs? It could get up into the high 80's upstairs.

[beenthere]

You would save some money.
But, loose comfort upstairs, when you went to bed.

Set it a few degrees above what you normally have it at. And set it to recover an hour or 2 before you go to bed.

[beachtech]

You would save some money.
But, loose comfort upstairs, when you went to bed.

Set it a few degrees above what you normally have it at. And set it to recover an hour or 2 before you go to bed.

or if the stat has adaptive intelligent recovery it should be at setpoit or close to it by the set time :)

like a vision pro 8000 series stat or the IAQ stat :)

[bluefitness]

You would save some money.
But, loose comfort upstairs, when you went to bed.

Set it a few degrees above what you normally have it at. And set it to recover an hour or 2 before you go to bed.

The area is not used at all. My master bedroom is downstairs. So, is it better to have the larger unit (5 ton) run for extended periods and possibly short cycle, or is it better to have the smaller unit 2.5 ton to offset some of the load in the house.

[beenthere]

If its not used at all.

Then you should have a thermostat installed, that can cool to dehumidify.
Set it to 85° temp, and set the humidity for 50%.

And let the first floor unit run as it needs.

[beachtech]

If its not used at all.

Then you should have a thermostat installed, that can cool to dehumidify.
Set it to 85° temp, and set the humidity for 50%.

And let the first floor unit run as it needs.

ditto :)

[bluefitness]

What is the sequence of operation for these stats that can dehumidify? I'm guessing temperature set point takes priority over humidity. If I set it to 85 degrees and the room temperatures is 83, the unit wouldn't run even if the humidity level is above 50 percent. Is this correct? The reason I ask is that I live in a very humid state. I was always taught to leave the upstairs unit running a few degrees warmer, but to not shut it down. This is to remove humidity and reduce load on the other unit. Within the last few years, it seems like everyone is turning to humidity control because of the new stats that came out.

[beenthere]

You can set a limit of 3° over cool. If the stat is set for 85, and the temp is 83 but the humifity is above the setting, it will run to remove humidity. Or until it over cools that it is 3° lower then set temp.