Determining the correct HVAC size

[occidius]

I am currently contracted to build a home with a relatively reputable builder in the Huntsville, AL area. I had concerns that the HVAC system they installed was smaller that what would be required for the home.

Just to give a few details about the home, it is 3300 sqft, 1/3 of the celings are 12 ft and the rest are 10 ft. I know that I should have a Manual J done, but they aren't going to pay to have it done and I only need to make sure they are putting in the right size unit. As of know they are putting in an American Standard 5 ton unit in (model: 2A6B3060A1000AA). From everything I have checked on line about the sqft rule, I should have 1 ton for every 500 sqft. Is this an accurate estimate? Also, what increments do they make residential units in and up to (the largest AS unit I've found is 5 ton)?

Any thoughts or ideas would be greatly appreciated!

[Black Adder]

It's your house, if they won't pay for a manual J then you should pay for it yourself to make sure they are sizing correctly. It is little enough to pay for something that will affect your year round comfort for years to come. As far as sizes, most AC is stepped in 1/2 ton increments up to 5 tons for residential. Anything over that you should really look into 2 units as with 2 units you will certainly have a lot more control over heating/cooling the different areas of a house. ie: upstairs, downstairs. Can't tell by the info provided what size you need. There is not accurate "rule of thumb", wish there was it would make my job a little easier.

[occidius]

Any suggestions on how to find a HVAC person that is able/willing to do a manual J on the house?

The link to the floorplan can be found at http://www.pollardhomebuilders.com/iframe.php?page=showmodel&type=rendering&id=39

The insulation in the exterior walls is R-13 batt insulation, R-38 blown in ceiling, and the home is built on a slab. Home is full brick and the single car garage has been converted to a bonus room.

[occidius]

Oh, and the ceilings are 12 ft in the Family Room, Kitchen, Breakfast room, and hallway leading from the front door. All other ceilings are 10 ft.

[r22coolguy]

Try one fo your local refrigeration/HVAC parts houses for recommendations, heck they may be able to do it there. Try Johnstone Supply in Huntsville, I know here in Baton Rouge they are great and helpful. Ask them to point you in the right direction. Also, your HVAC sub-contractor should be able to do it for you as well, or knows where it can be done.

[dan sw fl]

Originally posted by occidius
... a relatively reputable builder in the Huntsville, AL area.

a few details about the home
3300 sqft
1/3 of the celings are 12 ft and the rest are 10 ft.

I know that I should have a Manual J done, but they aren't going to pay to have it done and I only need to make sure they are putting in the right size unit.

As of now they are putting in an American Standard 5 ton unit in (model: 2A6B3060A1000AA).

From everything I have checked on line about the sqft rule, I should have 1 ton for every 500 sqft. Is this an accurate estimate?

How is the house oriented ?
Front of house faces ___ N S E or W

Are the windows tinted ?
Shading Coefficient ( SC ) =
or
Solar Heat Gain Coefficient ( SHGC ) =

8 windows on back
4 windows on right
5 windows on front
2 windows on left
19 windows = ~ 300 square feet total

Any slidng glass doors added as option?

House dimensions: ~ 58'x 54' or 3,132 Sq. Ft.

Manual J can be performed if you know window properties.

Clear glass
U-Value = ~ 1.1 and SC = ~ 0.75.

Please confirm TINTED or clear.

5-ton might barely work with Tinted windows.
Design Outside Temp 93'F ?
Inside 75'F ?

Request variable speed air handler.

[occidius]

None of the windows are tinted (they are double paned, single hung). The house faces the east and there are no sliding glass doors. The HVAC units have already been installed so I don't think I can ask for a variable speed handler without having them replace it with a larger unit (which is why I need to confirm whether or not the unit is large enough). The total heated and cooled space in the house is rougly 3300 sq ft. I may not understand what the sq ft number you came up with represents as I am a complete idiot when it comes to HVAC systems.

As far as temperatures, it can reach to over 100 degrees during the summer time. This year alone we had several weeks of 100 degree + weather. Interior temp is usually set between 70 and 72 degrees.

Thanks again for any help and guidance you can provide.

[pulaskihvacr]

FYI: I live in Fayetteville TN, and teach HVACR in Pulaski. Square footage has little to do with your required load. My home has 5200 sq ft of conditioned space and is very well heated and cooled with a slightly modified 3 ton Rheem gas pack.

[NormChris]

http://hvaccomputer.com/talkref.asp


http://hvac-talk.com/vbb/showthread.php?threadid=33866

[shaac]

Have a professional HVAC company perform a load analysis on the house. Anything else will be pure speculation.

[contactor]

You can go up to the info bar and click on HVAC Calc. Great for homeowners. Under 50 bucks.

[dan sw fl]

Originally posted by occidius
I may not understand what the sq ft number you came up with represents as I am a complete idiot when it comes to HVAC systems.

> 100 degrees during the summer time.
This year alone we had several weeks of 100 degree + weather.

Interior temp is usually set between 70 and 72 degrees.


Outside dimensions are __ ' x __ '

70'F
L.O.L.

NOT in this house when its > 90'F

[haaar]

Go to ACCA.ORG then search for an ACCA contracter in your area. They will preform a proper heat load.

[dan sw fl]

Originally posted by occidius
The total heated and cooled space in the house is rougly 3,300 sq ft. I may not understand what the sq ft number you came up with represents ...

Outside Dimensions:
For Example, 50' x 60'= 3,000 Sq Ft

So, What are the actual dimensions?