Filter
Top Products
FAN FUNDAMENTAlS
129
Introduction to FAN SELECTION
This is a guide to the most basic fan sections, all of which enable you to select the right fan for the job. It will answer the
following questions (and more):
• What is a SONE?
• How are model numbers and performance tables used to select a fan?
• How are direct drive and belt driven fans different?
• What types of motors are used with these fans?
The goal is to understand and use the Greenheck literature as an important tool in filling a customer’s fan order.
TERMS
cfm Cubic Feet Per Minute. A measure of airflow.
Ps Static Pressure. Resistance to airflow measured in inches of water gauge.
sone
A measure of loudness. One sone can be approximated as the loudness of a quiet refrigerator at a distance of 5 feet. Sones
follow a linear scale, that is, 10 sones are twice as loud as 5 sones.
Bhp Brake Horsepower. A measure of power consumption. Used to determine the proper motor horsepower and wiring.
hp Horsepower. Used to indicate a fan’s motor size.
rpm Revolutions Per Minute. Measure of fan speed.
TS Tip Speed. The speed of the tip of a fan wheel or prop measured in feet per minute.
AMCA
Air Movement & Control Association. A nationally recognized association which establishes standards for fan testing and
performance ratings. AMCA also license air volume and sound certified ratings.
MODEL DESIGNATION
For Greenheck belt drive models, the model designation
tells the model type, size and the motor hp.
EXAMPLE: GB-090-6
Model is GB hp is 1/6
Nominal Wheel Dia. 9 in.
For direct drive units, the model designation tells
the model type, the size and the motor/fan rpm.
EXAMPLE: G-121-B
Model is G rpm is 1140
Nominal Wheel Dia. 12 in.
MOTOR INFORMATION (Belt Drive Only)
When specifying a belt drive fan, the model designation
does not completely describe the unit. Additional
information about the motor is necessary. These items
are listed below:
MOTOR ENCLOSURE
This will be either “Open” (open, drip proof), “TE” (totally
enclosed) or “EXP” (explosion-resistant). Open is the
most common and will be supplied unless otherwise
specified.
SPEEDS
Motors are available in either single-speed or two speed.
Single-speed motors are 1725 rpm. Two speed motors
will be 1725/1140 rpm. Single-speed will be supplied
unless otherwise specified.
ELECTRICAL CHARACTERISTICS
Voltage and phase. Voltage can be 115, 208, 230 or 460.
Phase is either single-or 3 phase. A 115 volt, single-
phase motor is shown as 115/1. Typically, motors of
1/2 hp and less are single-phase. Motors of 3/4 hp and
greater are 3 phase.
This table
lists model
designation
suffixes for motor
horsepower and
fan rpm.
BELT DRIVE DIRECT DRIVE
Suffix Motor hp Suffix Fan rpm
6
1
/
6
A 1725
4 ¼ B 1140
3
1
/
3
C 860
5 ½ D 1550
7 ¾ G 1300
10 1 E 1050
15 1½ F 880
20 2 P 1625
30 3
50 5
75 7½
DIRECT DRIVE
Selection of direct drive fans (those with the motor shaft
connected to the fan wheel or propeller) is nearly the
same as belt drive selection. However, there are two
differences worth noting. Where belt drive fan speed can
be altered by adjusting the motor pulley, direct drive fans
(since they have no pulleys) must use a different method.
To adjust a direct drive fan’s speed (also motor
speed) or to provide a means of meeting an exact
performance requirement, a speed control can be
furnished. Speed controls vary the voltage supplied to
the fan and slow
it down; a principle similar to the way dimmer light
switches work.
Models CUE and CW, sizes 060-095 and Model SQ,
sizes 60-95, are provided with 115 volt, 60 cycle motors.
The three speeds are 1550 rpm (D), 1300 rpm (G) and 1050
rpm (E). Changing a motor lead is all that is necessary to
change speeds. When selecting a model with a 3 speed
motor, it is recommended that the G speed be chosen
whenever possible. This is the middle speed, which gives
the greatest flexibility in air volume because airflow can be
increased or decreased simply by changing a motor lead.
1
2
TYPICAL MOTOR TAG - Electrical Instructions
Suffix Letter Motor Speed Wiring Connections
D 1550 rpm White to L1 Black to L2
G 1300 rpm White to L1 Blue to L2
E 1050 rpm White to L1 Red to L2
Fan Fundamentals