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Q.  How do I calculate the proper size Heating Air Conditioning System HVAC units for my needs?
A. There are 3 methods that can be used to help you determine the proper sized equipment you need to purchase.  The first two are the easiest as you can do them in a matter of moments. The last method, being the most accurate, is the most time consuming.
Method 1- Compare to existing system
Method 2- Use the Map and Charts
Method 3- Do a residential load calculation

There is a Character Limit so this will only be for method 1- see other guides for method 2 and 3.

Method 1:  If you are replacing your existing system due to a malfunction or for a more efficient unit, you can use your existing system to help you determine proper sizing. The accuracy of using the existing system depends on if the proper calculations were done by the original installer of the equipment, so please keep that in mind. Use this method along with one of the other methods to help check for accuracy.

Heating Systems: Manufacturers of units use the rating of Btu to determine the accurate size of a unit. Select a system with comparable sizing to existing equipment. If the Btu is not listed on the unit you can decode their model number.

Q. How do I decode manufacturer numbers?
A. Manufacturers put their ratings into the model numbers of units.
For Example: HEIL model N8MPN050
The number 50 in the model number indicates the unit is 50,000 Btu's

Cooling Systems: Manufacturers of units use the rating of tonnage to determine the size of a unit, however they do not list the tonnage on the unit, but it can be decoded from using the model number and a basic math calculation. 

This can be done in 3 easy steps.
 
For example- HEIL model NAO24.
 
Step 1: The number 24 in the model number indicates the unit is 24,000 Btu's

Step 2:  In heating and cooling terms, 1 "ton" equals 12,000 BTU.

Step 3:  Now it is time to do a little math.  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.

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A Complete list of Frequently Asked Questions (FAQ) with those Questions (Q) and their Answers (A) being found by reading our helpful section in our store FAQ