How many square feet can each ton of airconditioning cool?

In central Texas, I use a real rough rule of thumb, depending upon the age/construction/etc (i.e. perimeter of house in lineal feet, #stores, type of & thickness of insuation, type of windows and doors, direction the house faces, size of duct work, number of occupants) of the home, of 450 sf to 700 sf per ton. If asked, I make sure the client knows only a qualified HVAC contractor should be used to perform a Manual J or other load calculation for an accurate answer.

Thanks Michael;
I really appreciate the help. And i’ll be sure to cover my butt with the caveat.

That is totally an “unknown”!

That may be how it was designed, but is not “how it should be designed”

I get calls from Realtors/Builders/Sub-contractors that ask; “why are you the only one that says that this is wrong…”?

Just because everyone dose it wrong, does not make it right!

Tonnage is determined by finding how many Btu’s/hr must be removed from the area served to maintain indoor design temperature under prescribed outdoor weather conditions and internal load estimates for that particular city.

If you have a quick way of determining this, you have the answer to your question. There is no quick way, so there is no answer I guess.

David’s got it just about right.

“Rule of thumb” works well if you’re cooling your thumb…otherwise, actual calculation is the best rule.

Here is a very easy tool to figure out th appropriate tonage.

Yup, I have that one in my flip book as “how the other guys do it”!!!

I should put that on my web site!

I laughed pretty hard…thank you!

There are many factors that go into determining the tonage needed. A Manual J calculation is the only real way to know how many tons you need for a home.

rough estimate 1 ton per 450 - 700 sq. but as a NACHI memeber are you to calculate or report this, Check out NACHI SOP 2.5.II.A. Inspector not required to determine (size, capacity, BTU)


Frigging Brilliant