Enough A/C tonnage?

Question

I bought a house in the Dallas, TX area last May. We have three units. two 2.5 ton units, and a 3.5 ton unit. My house is just under 4500 square feet and insulated relatively well.

Anyway, we called out the A/C company because the house just didn't seem to be cooling down enough. The guy said the ducting was not done right, and he would check with our warranty company to see if it would be covered. Well they call back and said yes and the owner of A/C co. would come out and see what all needed to be done. He came yesterday and said the real problem is we don't have enough A/C capacity for our size house. We are at 8.5 tonnes now and he said we really need to be around 14, given our square footage and high ceilings. He said at a minimium we need to add a 5 ton unit which is around $7,000. It is a new home, so i asked if there is any building code that dictates how A/C should be in a house. He said no and no warranty coverage to fix this issue. Does this sound right?

Answer 1

pending on your local building codes this should be inspected.

As a general rule of thumb 800 sf to 1000 sf per ton is used as a guide for sizing the system. the other issue is the duct size and design, return size and location of the return(s). If you have only one return, do you have enough free flowing air from each room back to the return ? need more info about the home to offer more advice.

Answer 2

There is never a magic number when the house is not a model  home.In other words,when the house is a custom home,the heat load calculation factors are many.

500 ft per ton is an average although vaulted ceilings,windows,sun direction,insulation,any many more factors will determine the actual tonnage on a custom home.There are always unique stuations that really become an issue whwn the home is lived in for a year.The builder will always be as close as possible because too much a/c is not the solution, as well as the additional costs.Good luck.

Answer 3

I have also am also having this problem. Our home is

2432 sq. ft and we have an 4 ton unit, we where told we need a 5 ton unit.  We were told 4 ton goes up to 2400 sq. ft. so I guess you can average it out from there. I guess it's about 600 sq. ft. per ton, that's my best guess.

Answer 4

In most cases it is a rule of thumb that one ton of a/c can cool 400-500 sqft, so 4500 sf needs around 9 tons of a/c. The way the home faces to is real important n to s or e to w. The attic temps will play a big role on how to a/c works in the day time under a heavy load. I have seen on the weather your day time temps have been near 100, the a/c systems are btu pumps and will remove heat at a certain rate, if it is really hot is could be normal. IF you add that 5 ton unit you will start to have a humidity problem in the home, the house will cool down too quick, plus the electric bills will go up big time. 7000 dollars for a five ton system is too much money. Call some body who can do a good job at seeing the whole picture not just the a/c systems but the house its self.