Sizing Heating, Cooling

and Ventilation Systems

 

 

 

 


 
Heating Systems

Establish which zone you live in and refer to the charts below to assist you in determining the right size system for your needs.

 

http://www.acdirect.com/images/climatezone.gif

Payne
Trane
 
 
Cooling Systems
Payne
Trane
 
 

 



Air Conditioning Square Footage Range
by Climate Zone

ZONE 1 

ZONE 2

ZONE 3

ZONE 4

ZONE 5

1.5 Tons

600 -
900 sf

600 - 950 sf

600 - 1000 sf

700 - 1050 sf

700 - 1100 sf

2 Tons

901-1200 sf

951 - 1250 sf

1001 - 1300 sf

1051 - 1350 sf

1101 - 1400 sf

2.5 Tons

1201 - 1500 sf

1251 - 1550 sf

1301 - 1600 sf

1351 - 1600 sf

1401 - 1650 sf

3 Tons

1501 - 1800 sf

1501 - 1850 sf

1601 - 1900 sf

1601 - 2000 sf

1651 - 2100 sf

3.5 Tons

1801 - 2100 sf

1851 - 2150 sf

1901 - 2200 sf

2001 - 2250 sf

2101 - 2300 sf

4 Tons

2101 - 2400 sf

2151 - 2500 sf

2201 - 2600 sf

2251 - 2700 sf

2301 - 2700 sf

5 Tons

2401 - 3000 sf

2501 - 3100 sf

2601 - 3200 sf

2751 - 3300 sf

2701 - 3300 sf


Proper System Sizing
The sizing chart above is not the scientific method to calculate proper system sizing. However, this chart is useful to help you determine your approximate system size requirements.
In order to scientifically calculate how many BTU's your environment requires, you must perform a Residential Load Calculation.
Another method is to determine the system size that is currently in place. The manufacturers do not list the tonnage on the unit. (very helpful, huh?) The system capacity will be coded into the model number of the outdoor unit.
For example, model CKL24-1 is a 2 ton unit. Why? There are 12,000 Btu's per ton. The number 24 in the model number indicates the unit is 24,000 Btu's, divided by 12,000 Btu's per ton, equals 2 tons.
 
24,000 Btu's/12,000 Btu's per ton = 2 tons
Use the following conversion information to determine your existing system size (use the model number NOT the serial number)
  1. 18 = 1.5 tons
  2. 24 = 2 tons
  3. 30 = 2.5 tons
  4. 36 = 3 tons
  5. 42 = 3.5 tons
  6. 48 = 4 tons
  7. 60 = 5 tons


When you are selecting the correct system size, be careful not to make the mistake of getting one which is too large. If the system you install is too large for the space, it will short cycle. In other words, the compressor will not run long enough to dehumidify the space and will limit your comfort. In addition, it will cycle on and off more frequently, increasing operating costs and reducing the system life.
If you're still unsure which system size is right for you, please e-mail us or call our toll free number at 1-888-766-5421. An experienced design technician will be happy to assist you.
 


Heating Square Footage Range by Climate Zone

ZONE 1 

ZONE 2

ZONE 3

ZONE 4

ZONE 5

30 - 35 Btu's per square foot

35 - 40 Btu's per square foot

40 - 45 Btu's per square foot

45 - 50 Btu's per square foot

50 - 60 Btu's per square foot

 

Heating Guide
Use the lower of the two numbers if your home is well insulated and the higher number if it is older or poorly insulated. (Hint: Use the larger of the two numbers above if you're unsure of your home's insulation)
Simply multiply the appropriate factor above by your home's total heated square footage to arrive at your approximate required heating capacity. For example, if you live in the yellow zone, your home is well insulated, and you have 2000 heated square feet, the equation will look like this:

 

2000 square feet
X .40 heating factor (from the chart above)
80,000 Btu actual output
Then, to calculate the output on a gas furnace, multiply its efficiency rating by its listed input rating for the actual Btu output of heat. For example, if a furnace has a listed input rating of 100,000 Btu's and an efficiency rating of 80%, it will produce
 
100,000 Btu input
X .80 efficiency
80,000 Btu actual output
If the same 100,000 Btu furnace has an efficiency rating of 93% it will produce:
 
100,000 Btu input
X .93 efficiency
93,000 Btu actual output
For this example, using an 80% efficient furnace, the 2000 square foot home above would require a 100,000 Btu input furnace which will produce the necessary 80,000 Btu's output of heat.


If you're still unsure which system size is right for you, please e-mail us or call our toll free number at 1-888-766-5421. An experienced design technician will be happy to assist you.
 
Insulation Variables
Variables such as your insulation, type and number of windows, number of stories, construction type, etc. will greatly effect the correct sizing of your system. A general rule of thumb is that if your home is well insulated with newer style windows, you can select the smaller size system that falls within your total square footage. If your home is two story it will place less of a load on the system in the downstairs area as the second floor acts as additional insulation.
If your home is not well insulated, has older style windows, and/or a larger than average number of windows, you will want to select the larger system which falls within your square footage range. The less insulated and more windows within the environment, the more likely you will experience greater air and heat loss.

Contact Us for More Info
If you're still unsure which system size is right for you, please e-mail us or call our toll free number at 1-888-766-5421. An experienced design technician will be happy to assist you.

 

Contact Custom Craft Exteriors to have your heating and cooling system properly sized immediately.