A/C unit too small for the house?


  #1  
Old 06-30-10, 10:13 AM
bobed2121's Avatar
Member
Thread Starter
Join Date: Jan 2010
Location: Central Valley CA
Posts: 145
Upvotes: 0
Received 0 Upvotes on 0 Posts
A/C unit too small for the house?

Just had a service man come out to check our system. House is 2863 sqft. There are two 3-ton units, on the ground outside, that cool the house, 8 years old. One unit handles roughly 65% of the home and the remaining 35% by the other unit. The 35% unit does quite well while the 65% unit has to run, run, run just to bring it to 80 degree on a 100 degree day outside. This a single story home and the ceilings are quite high at least 12'. The AC man said that the 3ton unit was too small to handle that kind of area and a 4ton would be a better unit. The builder of the home is well established and has a tremendous reputation for craftsmanship.
Any thoughts on this? Would the builder put too small a unit on the house. Should a 3ton unit handle ~1860 sqft?
 
  #2  
Old 06-30-10, 12:42 PM
C
Member
Join Date: Aug 2008
Location: Texas, California
Posts: 1,412
Upvotes: 0
Received 7 Upvotes on 7 Posts
Have you thought about re-routing some of the cold air from the other unit ?
 
  #3  
Old 06-30-10, 01:09 PM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,491
Upvotes: 0
Received 8 Upvotes on 8 Posts
Only way to know is to do a heat load on the home. This will take at least an hour to do.
 
  #4  
Old 06-30-10, 01:23 PM
S
Member
Join Date: May 2009
Posts: 111
Upvotes: 0
Received 0 Upvotes on 0 Posts
Those 12' ceilings mean you are cooling the equivalent of 4300 sq ft house with 8 ft ceilings. For your climate and volume of room air I'd say you are undersized. Some builders will "round down" in sizing if they are pressured to keep the sales price low.
 
  #5  
Old 06-30-10, 07:44 PM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,491
Upvotes: 0
Received 8 Upvotes on 8 Posts
Can't go by size any more! You have to do a heat load!
 
  #6  
Old 07-01-10, 08:11 AM
bobed2121's Avatar
Member
Thread Starter
Join Date: Jan 2010
Location: Central Valley CA
Posts: 145
Upvotes: 0
Received 0 Upvotes on 0 Posts
Originally Posted by airman.1994
Can't go by size any more! You have to do a heat load!
Ok airman. How do I do a "heat load"?
 
  #7  
Old 07-01-10, 08:19 AM
S
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,190
Received 1,281 Upvotes on 1,219 Posts
My first thought as well - you have two identical units covering 100% of the home, can the airflow be changed to split the house 50-50 across the two?
 
  #8  
Old 07-01-10, 08:28 AM
M
Member
Join Date: Sep 2009
Location: U.S. Midwest
Posts: 1,173
Upvotes: 0
Received 0 Upvotes on 0 Posts
Originally Posted by bobed2121
Ok. How do I do a "heat load"?
Google "heat load calculator." Google is your friend.
 
  #9  
Old 07-02-10, 01:42 PM
jjrbus's Avatar
Member
Join Date: May 2010
Location: US
Posts: 271
Received 2 Upvotes on 2 Posts
Not sure Google is always your best friend. Me and Sargent Schultz we know nothing!! But I have been lead to believe that this is the best calculator to use. JIm

Download Cooling Load Calculator Free Downloadr Software: Calculator Prompter, ComfortAir HVAC Software, Free Rent Or Buy Calculator, ...

It's not free but sometimes you get what you pay for.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: