System Technical Support request form

Please visit Carrier Enterprise’s Main Customer Site. In the top menu bar select Documents. In the search box, input the Model# of your unit. Hit enter or select from the drop down menu. There you will find your installation instructions and product data. Then you just need to scroll in the document you select, until you find the blower performance data charts.

When checking airflow for cooling operation you must first take the furnace and set it up for cooling airflow when the furnace is operating for this test.

You may have to change the wire speed tap on your motor or IFC.

For the IFC take the wire used on the cool tap of the board and move it to the heating tap of the board for this test.

For a X13/Constant Torque motor take the wire from the heating tap and move it to the cooling tap for this test.

For a variable speed furnace without a User Interface adjust your dip switches to match the cooling airflow as close as possible.

Once the change has been made place the unit in the heating mode and turn off all other natural gas appliances. Go to the gas meter and time how many seconds it takes for the furnace to consume 1 cubic foot of gas. And then measure the temperature spilt of the gas furnace at the furnace.

Let’s say you had a Return Dry Bulb temperature of 75F degrees, and a Supply Dry Bulb temperature of 55F degrees, for a total of a 20F degree temperature split.

And our Calculated CFM was 1089

20F X 1.08 X 1089 = 23,522 BTU’s.

We had a Return Temperature Wet Bulb reading of 65.3F degrees, and a Supply Temperature Wet Bulb reading of 54.2F degrees.

We need to covert these temperatures into Enthalpy.

64.3 WB converts to 29.53

54.2 WB converts to 22.74

29.53 – 22.74 = 6.79 Enthalpy difference

Our Calculated CFM was 1089

6.79 X 1089 X 4.5 = 33,274 BTU’s.