1. Professional Member
Join Date
Apr 2005
Location
Richmond, Virginia
Posts
365
Post Likes
Don't you also need to know where the OP lives, what design temperatures he desires, and the orientation of the various windows and doors? How about the number of fireplaces and the number of people living in the house?

In central VA - richmond - tidewater area design is 95 F 76 wb.

Fireplaces are negliable since they would not be used for heating purposes. They do contribute to infiltration due to stack effect if the damper is not closed.

For a family of 4 thats 450x4=1800 mbh total or .15 tons.

Hopefully the sketch would have a north arrow, but you're right need the orientation of walls too.

2. Professional Member*
Join Date
Nov 2004
Location
SW FL
Posts
8,069
Post Likes

Originally posted by lit'l cat
Should the outside or inside of a house be used to figure load calc. 1 contractor measured inside (sd 2.5 ton a/c) the other measured outside & sd (3 ton a/c)
1,800 Sq.Ft., 300 Sq.Ft total Window area with Low E,
_____ Use 2.5 Ton ____

Low E ( S.H.G.C. ~ 0.46) requires 0.5+ ton less than CLEAR Glass ( SHGC 0.75). Room Temperature desired 75'F

S.H.G.C. Solar Heat Gain Coefficient
S.H.G.C. = 7/8 * Shading Coefficient

100 Sq.Ft. difference in floor + ceiling area may make Cooling load difference of << 0.2 ton
I use close to the Inside Area.

3. Regular Guest
Join Date
Nov 2002
Posts
94
Post Likes

Designer Dan,

Your post sd 1800sq ft use 2.5 Ton. My house is ~ 1600sq ft. In theory, that would make the tonnage even less, then wouldnt I have an airflow problem?

Before you answer, this is more a general question since I realize you have no detailed info abour my house

4. Professional Member*
Join Date
Nov 2004
Location
SW FL
Posts
8,069
Post Likes

Originally posted by lit'l cat
Your post sd 1800sq ft use 2.5 Ton. My house is ~ 1600sq ft. In theory, that would make the tonnage even less, then wouldnt I have an airflow problem?
It ALL Depends on ...

Blower + Blower Settings + Condenser +
+ Duct + Duct Transitions + Outlets + dT + %RH
+ Time of Day + Day + Month + ... +

+ Sunny + Cloudy + use of Ceiling Fans +
whether you have several visitors +

+ How it ALL Works together AS A SYSTEM! ? ______

5. Banned
Join Date
Aug 2002
Location
Office and warehouse in both Crystal River & New Port Richey ,FL
Posts
18,836
Post Likes

Originally posted by lit'l cat
Designer Dan,

Your post sd 1800sq ft use 2.5 Ton. My house is ~ 1600sq ft. In theory, that would make the tonnage even less, then wouldnt I have an airflow problem?

Before you answer, this is more a general question since I realize you have no detailed info abour my house

Less tonnage on existings ducts is seldome a problem.The throw from the supply grilles will be less ,with less total cfms,unlikely enough less to be a problem.Todays top of the line two speeds,run on low most of the time,and there's no problem.

Page 2 of 2 First 12

Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•

Related Forums

The place where Electrical professionals meet.