NOTE - sorry that I double posted my question, it was an accident and I don't see an option to delete the duplicate.
I have received several estimates, all with Manual J load calcs being done by the contractors. If proper load calcs were done then what would account for having 2 different sizing estimates? Shouldn't all load calcs yield the same result or are there certain Manual J variables that would lead to different results? I have estimates for a 2.5 ton system and a 3 ton system. I don't know if this is too general a question but as I make my contractor selection are there certain Manual J variables that depending on what they used would cause the sizing estimates to yield different results?
Currently I have a 3.5 ton system. I never felt uncomfortable inside but it could be slightly oversized based on short off/on cycles so 3 tons makes sense to me but with 2.5 being a full ton less than what I have I am not sure what to do now. I live in Massachusetts which has a fairly short cooling season.
Home is a split level raised ranch with around 1400 square feet of living space. Home is about 50 feet in length, 26 feet in width. House is on the sun side of the street so there is sun all day long. Upstairs is fully air conditioned, the downstairs has supply registers in only 2 of 3 rooms that are about 16 feet long and 13 feet wide. I know this is extremely general and windows, walls, house orientation are all a factor but just looking for a guideline as I talk to the contractors - If I have been comfortable with my current 3.5 tons does 2.5 make sense or is 3 tons more likely the way to go.
Also one more question. I like to have the inside temp at 72 degrees. Does this factor into the sizing so that if the contractors used 74 or 75 degrees do I need to tell them to use 72 degrees and would that yield a different sizing result?