Where Can I Find A Chart That Shows AC Tons For Sq Ft

[Ron]

I need a chart that shows what size AC (heat pump in this case) is needed for a certain amount of (heated/cooled) sq ft.

[Greg]

The "quick and dirty" is 500sf per ton of cooling but you really need to do a manual J survey to get the right number. The number here in Fla is not going to be the same as in Toronto and a CBS rancher is not going to be the same as a 2 story stick built.

[Joseph Meehan]

There is no such accurate number. Consider the cooling required to cool a 500 sq foot room in Florida with large south facing single pane windows, minimal insulation in the walls and a flat roof with little or no insulation to another 500 sq foot room in Centralia WA with a few small high E thermo windows extra insulation in wall and ceiling. They will not even be close.

The formula is called a Manual J (I believe) and any good HVAC tech will be able to do the formula for you. You will want that good tech because they are the key to how well your system is going to work. Unlike some activities in air conditioning size in not everything.

[Dr. Hardcrab]

"Greg" wrote

That's why so many people are dissatisfied with their HVAC systems. There are a lot of hacks out there that still go some "rule of thumb" when it comes to sizing units. I'll give you an example of my houses:

I lived in my last house for 16 years. It had 1700 square foot of living space. About 2 years before I moved out of it, I put a new furnace and A/C. Took all the measurements and popped it into the computer and came out to 3 Tons (alright, it was 2.8 tons). My dad decided to have me replace his 20 yrear old system because he was selling the house (at the time I did not know I would end up buying it). It is almost 2300 square feet and it took a

2 1/2 ton! (It heats and cools fine I might add).

I know that isn't that big of a difference, but it's just to show you how different it can be when the two houses are less than 2 miles apart (so it's the same climate). If i had used the "1 ton per 500 sq ft" method, I'd have almost a 5 ton in this house!

[m Ransley]

Yes get a good pro out to do a load calc. Im oversized and need 2 dehumidifiers to be semi comfortable. To big and you are left humid, to small and you wont cool. This is a service worth paying for.

[I-zheet M'drurz]

Why don't you guys take it to alt.hvac This is the group for stoopid home-moaner questions.

[m Ransley]

TP your sounding like PJM

[Red Neckerson]

"I-zheet M'drurz" wrote

;-]

[Travis Jordan]

Here you go:

[American Mechanical]

[Joseph Meehan]

I-zheet M'drurz wrote: ....

And I take it you are in charge of the stupid answers?

Maybe some homeowners want the right answers.

[nicksanspam]

Ouch. They heat the house air. Maybe you need a dirty AC filter instead, to send the latent heat outdoors with lower vecocity air in the AC and more dehumidification. Where does all this humidity come from? Air leaks? Water leaks? A damp basement floor?

Nick

[m Ransley]

I super insulated the house, and am in total shade on a lake , a tight house done to double to triple insulation standards. Next will be a furnace with a VS DC motor so I will be able to drop fan speed and double humidity removal.

[nicksanspam]

Is the lake in the house? :-) How do you get so much humid air into the house?

What were your blower door test results?

Nick

[~KJPRO~]

Sorry TP, we don't need them over there in a pro's group.

~kjpro~

[m Ransley]

It is an extremely tight super insulated house of 1875 sq ft including heated basement. Zone 6 , to -15f in the midwest. Last years total gas bill for heating , hot water and dryer and gas cooking was 336.50 I just need 1 ton not 2 of AC, I have no leaks so don't second guess the situation . My yearly gas bill proves it. And no supplemental heating is used. Buildings can be upgraded for true efficiency

[I-zheet M'drurz]

Whew!

SOMEBODY got it. I was getting a little worried there.

[nicksanspam]

And where did you get the idea it's a "pro's group"? :-)

Nick

[I-zheet M'drurz]

You're obviously not in charge of senses of humor.

Maybe some of them recognize a sarcastic joke when they see it.

[I-zheet M'drurz]

Hardcrab *IS* one of you guys. That was the whole point. Sarcastic humor is obviously lost in this place I guess.