The CFM of the equipment are given, how to calculate Static Pressure for it.
You need 350 to 400 cfm per ton (12,000 btu) of cooling. So, divide your cfm by 400. For example, a 1200 cfm blower on an air handler could handler up to 3 tons. All calculations depend on your duct being the proper size for the equipment.
20x20
20tr cfm calculatin
To calculate CFM (cubic feet per minute) using a manometer, measure the pressure difference across a restriction in the airflow system. Use the manometer reading and the area of the restriction to determine the velocity pressure. Then, use the velocity pressure to calculate the airflow in CFM using the formula CFM = (Velocity Pressure * Area of the Restriction) / 4005.
increase the cfm for the ahu
To calculate the horse power of a compressor one would need to use the following calculation. Pump ratio x GPM @ 100 psi = CFM. For a gas compressor divide CFM by 2 and for an electric compressor, divide CFM by 4. GPM is gallons per minute and CFM is air consumption in cubic feet per minute.
To calculate sensible heat, you can use the formula: Sensible Heat (BTU/hr) = 1.08 x CFM x Temperature Difference (°F). Just multiply the CFM value by 1.08 and then by the temperature difference in Fahrenheit to get the sensible heat in BTU per hour.
To calculate CFM (cubic feet per minute), you need to know the volume of the space in cubic feet and how many times you want to replace the air within one minute (air changes per hour rate). Multiply the volume of the space by the air changes per hour rate and divide by 60 to get the CFM required for that space. CFM = (Volume in cubic feet * Air changes per hour) / 60.
This will depend greatly on the filter you want to use. A flat filter will need to be larger than a pleated filter. Determine what efficiency you need from your air filter. Look up the maximum "face velocity" across the filter, most are around 500fpm. Divide the blower cfm by the filter fpm and you will end up with ft2 or filter needed. Let's do an example of a 2000cfm blower with a filter that requires a face velocity of 400feet/min. 2000ft3/m / 400ft/m = 5ft2 or (1)24"x30" filter.
Go here to order Ac Delco part # 15-80860 blower motor resistor for $14 plus ship and handling http://www.oehq.com/index2.cfm?showpage=utility/partsearch2.cfm GM Dealer only. I got mine from Autozone.com. About $14.00
cfm=.32X(aXb)Xface velocity/144 a= width b=length