Question:
My house is about 2,000 Sq. Ft, in New Jersey. We have Vinyl Siding.
The contractor suggested a 2.5 ton unit (30,000 BTU) based on teh
Windows, size, etc.
I wonder if thats large enough?
We currently have a number of individual units, and their total BTU is
around 45,000.
Even using 20* 2,000 SQ/Ft = 40,000 BTU
The contractor is reputable, and seems knowledgeable. I don't think a
larger unit costs much more and generally contractors will be happy to
sell a more expensive unit, as they make a bit more.
I'm just concerned that 30,000 is not enough.
Answer:
I guess you didn't read the article.
http://www.proctoreng.com/articles/bigger.html
The "square-foot-per-ton" sizing method avoids calculating the cooling
load of the building and proceeds directly from the square footage of
the building to the size of the air conditioner. No contractor submitted
such a method for approval but a number of contractors reported that
they often used this method, or knew others who did. In a study by the
Florida Solar Energy Center, 25% of the contractors reported that they
size by floor area (see "How They Size Air Conditioning Systems in
Florida," above).
While this approach is rapid and simple, it does not account for
orientation of the walls and windows, the difference in surface area
between a one-story and a two-story home of the same floor area, the
differences in insulation and air leakage between different buildings,
the number of occupants, and many other factors. In some cases
contractors attempt to cover these variables by categorizing the home as
low (a new home in a moderate climate), average, or high (an old home in
a hot climate) but this method also falls short of properly sizing air
conditioners.
