46 posts, read 182,329 times 3,191 posts, read 6,854,645 times well since hubby is in the HVAC biz and sitting right here, I'll try to pass on what he is saying... 2 AC systems in a 2 story home is used to provide the same heat & cooling temperatures on both levels. ( warm air rises, therefore more cooling may be needed there If you had one system without zoning, the upstairs will often be warmer than down. Some companies put in a zoning system to monitor each level ,with one AC system, to help maintain the same temperature throughout the whole house. 2 AC systems on a 1 story may be needed if the house is large or the length of the house is very long, or depending on the layout /locations of certain rooms. The largest residential AC system is 5 ton. There are some one story homes that need more 5 tons of cooling. To determine what size unit is needed, a qualified HVAC contractor will perform a manual J load calculation. hope that helps you some

684 posts, read 1,642,638 times 27,236 posts, read 33,636,824 times Originally Posted by workingwifeandmom This is just supposition, but what if you wanted two different temperatures in different areas of the house, or for an addition to the house? You would need two units in that example, wouldn't you? 8,535 posts, read 12,566,730 times crazyma stole my thunder..... it is VERY important that the HVAC contractor perform the ACCA Manual J calculations to determine the heating / cooling loads of the house..... that way, the system(s) can be sized properly, giving you the best efficiency for the space and your buck. 385 posts, read 935,462 times 16,275 posts, read 44,896,608 times Originally Posted by latetotheparty You are VERY correct in restating this!! There is no eye balling it, there is no ton per every so many sq feet 'rule'. Every house is different!! ( and there are 'contractors' out there that have no idea what a manual J is scary thought ain't it)

4,010 posts, read 7,401,586 times 3,750 posts, read 15,267,568 timesStep 1 / 3:Edit First, tell us little about your home: Tell us about your needs and we'll recommend the right system for you and your home. WHAT TYPE OF SYSTEM ARE YOU LOOKING FOR?best place to put ac unit Continue to Step 2car ac repair for cheap Continue to Step 2buy central ac unitOnce you have the size of the area that you are wanting to install the air conditioner in, follow the guide below to determine your approximate kw range. Suitable for rooms approx 10 - 25 sq meters Suitable for rooms approx 25 - 35 sq meters Small rooms with high ceilings 5 - 6kw Range Suitable for rooms approx 35 - 60 sq meters Mid-sized rooms with high ceilings