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Question DetailsAsked on 8/7/2012

What size a/c unit is needed for a 2900 sq. Ft. Home? One story home with 9 ft ceilings with upstairs bonus playroom. Approx. Cost?

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5 Answers


Despite the widespread belief even by some contractors, there is no acceptable "rule of thumb" to determine the correct size. Check look under Quality Installations.

ACCA( Air Conditioning Contractors of America) is the authority on determining the correct size, it's a Manual J Load calculation,folowed by a Manual S Equipment selection,to meet the Load calculation.

Manual J requires a detailed sketch of the home, showing room sizes ,window sizes,exposure to sun,etc,etc.

Manuals are the ANSI approved standard for doing so.

Call around for contractors,starting with those on Angie's List,and ask if they can perform both Manual J and S, keep calling until you find ones that can.

Under or over sized eqipment will never perform as well, save the energy, or keep you as comfortable as the correctly sized equipment.


Answered 7 years ago by BayAreaAC


with a normal situation 2900 sq ft will require a 3.5 ton unit, but you have 9 ft ceilings. I would suggest installing two units a 2 ton unit and a 2.5 ton unit. I would split your area in two. Living room, bonus room and kitchen for the smaller unit and the bedrooms for the rest of the house. This way you control your comfort. Operating cost will stay the same as if you install one big unit for the hold house maybe even less.The indea behind this is that you do not occupy the entire house at the same time this way you control your comfort. You have more traffic in the living area so you do not need it be be cooler than your bedrooms or you will want it to be cooler in the living area than your bedrooms it your choice.

Raymond Gonzalez
koolray heating and air


Answered 7 years ago by Raymond Gonzalez


What area of the country is this home in, what is the orientation of the home(which direction does the front door face), what type of windows & how many windows & what square footage are the windows, what type & what R- value is the wall/ceiling insulation?
Manual J load calculation is the only answer for the proper sizing of Heating & Air Conditioning equipment.
Find a quality contractor in your area who performs these calculations, and is properly licensed, to give you a quote on your comfort system!

CSLB# 824188


Answered 7 years ago by AirTekHP


Remember that for every Ton of cooling (12,000btu) 400 to 500sq.ft. is required if you live in a climate like the upper mid west average annual ambient temp 70* and below 500sq. is adequate per Ton higher then 70* 400sq. best bet for you would be two 3 ton High effeiciency Systems. Price around $8,500 location of these systems will make cost increase or decrease

Answered 6 years ago by BLamping


Contractors that actually do 'load calculations" will tell you there is no rule of thumb. It can range from one ton per 400 sq ft to one ton per 750 sq ft. Get a Manual J load calculation, and get the correct size system(s)!


Answered 6 years ago by BayAreaAC

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