Blower Fan Capacity Calculation

This fan calculator is typically used to calculate the cfm or cubic feet per minute of air exchange that may be desired in a building.

Whole house fan purpose. Fan capacity calculator the attma trade association has developed a blower door fan capacity calculator to help attma members calculate how many fans are required for level 2 buildings. Simply motor hp blower capacity in hp motor efficiency. The altitude the fan or blower will be operating at will also affect the density and performance of the fan or blower.

The very first thing you need to do is measure the fans total air pressure. Fan affinity laws affinity laws can be used to calculate volume capacity head or power consumption when speed and wheel diameters are changed fan inlet suction pressure and air density high suction pressure at a fan inlet decreases the density of air and should be corrected for proper selection of the fan. All of which have individual benefits volume pressure speed power efficiency etc but all of them will shift gases at the same rate based upon the input power.

Assume that this is a 10 ton capacity system as. 60 to 78 efficiency have twin lobe air blower here we took 69 efficiency. This is measured in inches of water gauge iwg.

Whether exhausting air or bringing fresh air into a structure the calculation produced should help to figure out the size of fans required to accomplish the air exchanges needed. The metric equivalent is meters m. According to the general fan law governing axial fans you will need to know the fan blade diameter and pitch blade tilt or attack angle along with the rpm variable to calculate cfm.

Impeller axial centrifugala sirocco etc. Differences such as efficiency or flow rate occur in the type of fan due to particular design advantages that favour one characteristic over another. Hp 425 x 853 229 x 069 109 hp say 11 hp power air blower capacity is ok.

There are a number of fan types. Blower and motor calculations by norm christopherson this section includes information on the sizing of motor pulleys changing rpm and cfm of blowers motor selection for blowers belt length changes and using fan laws for troubleshooting. In this example a small household fan on a stand has a three bladed plastic fan with a 1 foot diameter and an 8 inch effective pitch.

The fan capacity calculator works on the basis of some assumptions such as a quality power supply and running into a free air unobstructed route. Also included is information on motor efficiency. 1 ft 30480 x m.

Now we should find motor capacity in hp. This is the unit of measure which is used for various fan calculations. Quieter than built in blower can be sized for length of duct run duct under negative pressure safest operation 10 stack height per nfpa 45 horizontal runs taper back to hood 3 5 duct diameters between elbow and blower blower mounted on bushings challenge blower with a damper damper.

Chart found on page 5 of instructions for how to properly select a fan or blower. In order to calculate it you must place one of the ends of a manometer where the fan inlet is.