I have a problem with my upstairs bonus room being approx. 10 degrees hotter than the downstairs during the summers (on the south side of the house)... already experiencing it now! It is approx. 180 sq feet and also has a walk in closet and bathroom, and the stairwell. 2 vents in the room, 1 each in the closet, bathroom and hall. This room has an electronic thermostat that only controls whether the damper is open or closed.

I am exploring two options: 1 - portable unit exhausting out the window and 2 - installing a dual zone controller to control the a/c coming on for the two zones. This would require another damper be installed.

Which is my best option and any recommendations on size and or equip?

Are there any returns upstairs or just supplys?

Inless your duct work was set up to run to zone system then I dought it can be change to do so now.

Effective zoning would require a damper upstairs and a damper down stairs with 2 theremostats and a master controler. Plus a bypass damper located at your unit. What tonage is your ac now?

Sayno, and mitsubishi make very nice mini spilt units. You can get them up to 2 tons if need be. The are much quiter then a windo unit but also cost a bit more.

Are there any returns upstairs or just supplys?

Yes, one return 12x12.

Are you sure your t-stat is controlling your damper? With a 12x12 return and 5 supplys you should be getting plenty of air for the 180 sf area. Do you have a lot of windows in this room?

effective zoning would require a damper upstairs and a damper down stairs with 2 theremostats and a master controler. plus a bypass damper located at your unit. What tonage is your ac now?

The unit is a TRANE 2TTR2060B1000A rated 4275 CFM @ 0.0 IN.W.G. Hope that is what you were looking for.

Already have two thermostats, 1 downstairs (actually controls when unit comes on and off) and 1 upstairs (only controls the damper to the upstairs portion open/close).

Are you sure your t-stat is controling your damper? with a 12x12 return and 5 supplys you should be getting plenty of air for the 180 sf area. do you have a lot of windows in this room?

1 tstat upstairs only controls whether to open or close the damper based upon temp... since the room is always hot, it stays open. The tstat downstairs controls whether to turn the a/c on and since it runs cooler downstairs then up, the upstairs suffers. It does get plenty of air when the downstairs tstat calls for it.

1 window only, facing south side (has blinds on it). Walk out attic access.

Another option I considered is to run the fan(blower) continuously to get some airflow, but that only appears to drop the temp a few degrees.

I take it you have a fairly large house? What is the sf of the downstars area? And do the vents you have upstairs are they in the floor wall or celings?

Yes running the fan all the time will help some but as you just stated will only drop around 3 degrees or so. I just installed a sayno unit in my dads house. He was having the same trouble you are. And it have worked very well.

i take it you have a fairly large house? what is the sf of the downstars area? And do the vents you have upstairs are they in the floor wall or celings?

Total sq. ft. of house is 3150 with 180 of it upstairs room plus about 30 sf closet, 80 sf bathroom and 20 sf landing at top of stairs. (total up is about 310, down is 2860).

Vents are in the ceilings... all vents and ducting are accessible via attic.

yes running the fan all the time will help some but as you just stated will only drop around 3 degrees or so. I just installed a sayno unit in my dads house. he was having the same trouble you are. And it have worked very well.

Sanyo portable unit with window exhaust? What model and what BTU do I need to look for?

What is the temp in the attic? Is it vented or have a exoust fan. The attic temp being to high could cause you to have a 4 to 5 degree difference in you room.

Mitsubishi Electric - HVAC Advanced Products Division (http://www.mrslim.com/)

Giving the size you have stated. I would say a 9000, or 12,000 BTU would work great. Plus they are only 115 volt not 220

what is the temp in the attic? is it vented or have a exoust fan. The attic temp being to high could cause you to have a 4 to 5 degree difference in you room.

Attic is vented. Right now it is cooler than the room! However, during the day it can get quite hot. Having said that, the insulated door and seal seem to keep it all out and the walls are well insulated and remain cool to the touch.

Well if you are getting good airflow and you insulation it the attic is good. I would say that just the down stairs cools down to fast. Is you temp more even on the hottest days of summer when the unit runs longer is is it still of 10 degrees or so?

well if you are getting good airflow and you insulation it the attic is good. I would say that just the down stairs cools down to fast. Is you temp more even on the hottest days of summer when the unit runs longer is is it still of 10 degrees or so?

I would say that when it is running the temp difference drops from 10 to about 4/5 degrees which is at its best. It never really gets even.

Chigo Mini Split Air Conditioner (http://www.magicool.com/english/chigo/index.html)