How many tons are needed?

Is a 3 ton A/C system enough for a 3,100 sq ft house? Is it kind of small?

Square footage is not enough information to size the unit. There are many items that go into the calculation. Based on the average home in my area, that would be small. Your mileage may vary.

I would question it as it would have to have super delux insulation job but my most concern would be the lay out of the duct work in comparison to the furnace blower CFM. Improper CFM= no static pressure no air flow on the end runs it would not cut the mustard in Okla can not say about your area

Agree! If it was a newer manufactured home, due to their insulation etc., it would be the right size. It all depends what the AC is cooling and the set up of the system.

Cooling Calculations

Rule of thumb I have seen is 500 sq. ft. per ton.

Charley, that make sense for an approx. ?


What was the out come of the manual J?

Yes that was used many times does not work with modern technology I still use it as a base line before I start looking at the home

So as a baseline #, it would be somewhat close?:slight_smile:

Bruce had the answer for you.
The installation should have been based on the Man-J, as it adjusts for location and construction. South Texas is not the same as Alaska.

Close=Horseshoes & handgranades;-) Close for OK & Tx not for your area

Thanks for the insight. All of the other homes in the area had visibly larger AC compressors. I looked up this newly installed one by model number and found it to be only 3 tons. Think it was smart to call it out, even though newly installed. Thanks

Suggested having AC tech look at it and do calculations.

I know Charley, my house is only 1,500 sq. ft. and only need a 8,000 in one window and a 5,000 in another window for a couple of weeks a year. :slight_smile:

What is the manual-J ? Never heard of it…

Just saw comments about man-j.

Now days it is a computer program that calculates all factors of a home such as insulation, windows,doors, direction of the home in relation to prevailing winds, wall thickness and the type of material, the list goes on and on and determines the size of the unit

They need A/C in Alaska?