How many ton A/C unit might be good?

[ron in sc]

Garage is 624 sq. ft. Walls will be 9 1/2 ft. tall then angle up to center of ceiling which will be 14 ft. In other words garage will have a tray ceiling which will be 9 ft. wide and 26 ft. long with it being 14 ft. high in the middle. I mention this because there will be more space to cool.

I live in South Carolina so it is quite hot and humid.

I will have but one set of carriage doors for a vehicle to enter and of course garage will be insulated.

Contractor has said 1 1/2 ton unit will be fine but I kind of would like to obtain additional opinions.

 

[Roospike]

Yes , you will need to look at cubic feet vs the standard square feet but it wont change too much on 624 sf size place.

i can tell you now you dont want a A/C unit too big or over sized because it wouldnt take out the humidity. I lived in Shelby for 4 years and yes its very humid in the Carolinas.

 

[ron in sc]

you dont want a A/C unit too big or over sized

I will have an extra 2 1/2 ton unit from the downstairs part of my house I can use. With the addition to the downstairs I am having to upgrade that unit to a 3 ton unit.

Will the 2 1/2 ton be to big for my garage and not work right?

 

[Roospike]

I think 2 1/2 ton will be way too big for that size garage . You will get a blast of cold air to the garage but it wont run long enough to pull out the humidity.

 

[Roospike]

Oversized air conditioners run in short inefficient cycles. They waste energy since they must run for a few minutes at the beginning of every cycle just to cool down their coils, fins, and ducts. Only then can they cool and de-humidify your home. That original cool-down energy is lost after the air conditioner shuts off.

An air conditioner's ability to remove heat is expressed in Btus per hour, or “tons” of cooling. Each ton equals 12,000 Btus per hour. Your air conditioner should have a ton of cooling capacity for every 600 to 1,200 square feet of floor area, depending on your home's energy efficiency and your local climate.

A poorly shaded home with little insulation and lots of air leaks might need a ton of air conditioning for every 600 square feet of floor area. A well-insulated and well-shaded home with few air leaks might only need one ton per 1200 square feet.

 

[Roospike]

Sizing Air Conditioners

http://www.srmi.biz/Tips.Residential_A_C.AC_sizing.htm

 

[Roospike]

Have you looked into a window / wall unit A/C ?

In full units there rated by seer and the higher the seer the more efficient the unit will be.

In window units they go by EER and again the higher the EER the more efficient the unit. About the best window wall units i have seen are 11 EER and i also have a 11 EER 15,100 BTU window unit and its super efficient.

For your size shop / garage you might want to look at a 12,000 BTU - 15,100 BTU unit with a hight EER rating .