Fan Selection
Application-Based Selection
Performance Theory
SELECTING THE RIGHT FAN FOR THE JOB
This book is designed to help you select the fan that will best
fit the application for which it is intended. With the large
number of different fan types and sizes available it's
necessary to know which fan model does the best job in
certain applications and then be able to select the most
economical fan size for the job.
With that in mind, this guide is constructed in three sections.
Section One describes how to select a fan using catalog
performance tables with a given air volume and static
pressure. This section also interprets Greenheck model
numbers and illustrates the relationship between fan speed
and airflow.
Section Two covers the basics of fan selection—determining
the proper fan model, air volume, static pressure and
loudness appropriate for a given application. This is
important when your customer does not know the amount of
air to be moved or the resistance to airflow that will be
encountered. This section also illustrates proper fan
installation and proper wheel rotation.
Section Three goes beyond fan selection with information
of a more comprehensive and technical nature about air
movement and air systems.
TABLE OF CONTENTS
SECTION 1
INTRODUCTION TO FAN SELECTION
Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Model Designation . . . . . . . . . . . . . . . . . . . . . .4
Reading Performance Charts . . . . . . . . . . . . . .5
Matching a Specification . . . . . . . . . . . . . . . . .7
Cross Reference Chart . . . . . . . . . . . . . . . . . . .8
SECTION 2
FAN SELECTION BASED ON FAN APPLICATION
Basic Overview. . . . . . . . . . . . . . . . . . . . . . . . .9
Commercial Kitchen Ventilation . . . . . . . . . . .10
General Commercial Ventilation . . . . . . . . . . .12
High Static Pressure Ventilation . . . . . . . . . .15
Determining CFM . . . . . . . . . . . . . . . . . . . . . .16
Determining Static Pressure . . . . . . . . . . . . .17
Sound Levels . . . . . . . . . . . . . . . . . . . . . . . . .19
Motor Horsepower . . . . . . . . . . . . . . . . . . . . .19
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Wheel Rotation . . . . . . . . . . . . . . . . . . . . . . . .20
SECTION 3
FAN PERFORMANCE
Fan Dynamics . . . . . . . . . . . . . . . . . . . . . . . . .21
System Dynamics . . . . . . . . . . . . . . . . . . . . . .21
Combining Fan and System Dynamics . . . . . .22
Adjusting Fan Performance . . . . . . . . . . . . . .23
Fan Laws . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
INTRODUCTION TO FAN SELECTION
This is the first and most basic of this manual’s three
sections, all of which are designed to enable you to
select the right fan for the job. Look at this first section
as a “user’s manual” for Greenheck literature. 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
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 and Control Association. A nationally recognized association which
establishes standards for fan testing and performance ratings. AMCA also licenses air
volume and sound certified ratings.
belt driven fans different? What types of motors and
accessories are used with these fans? Are there
Greenheck fans that will match the size and
performance of fans from other manufacturers? The
goal is to understand and use the Greenheck literature
as an important tool in filling a customer’s fan order.
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.
4
The table below lists model designation suffixes for
motor horsepower and fan rpm.
Belt Drive
Suffix Motor hp Suffix Fan rpm
6
4
3
5
7
10 1 E 1050
15 11/2 F 680
20 2 P 1625
30 3
50 5
75 71/2
1
/6 A 1725
1
/4 B 1140
1
/3 C 860
1
/2 D 1550
3
/4 G 1300
Direct Drive
Reading Performance Charts
The most important part of selecting a fan is the ability
to read the performance charts. Most of the
performance charts in the catalog are similar and are
read in the same manner. Models RSF and BCF are
Belt Drive Selection
Assume that a job requires a belt drive roof exhauster
to move 1000 cfm against 0.25 in. Ps. Refer to the
performance model at the bottom of this page. Start at
the top of the chart with the 0.25 in. Ps column. (All
numbers in this column correspond to .25 in. Ps.) Now
follow the column downward until a value is found that
slightly exceeds 1000 cfm. In this case, 1012 cfm is the
first box that meets the requirements.
Note: Notice that each performance box is divided into
3 smaller boxes. The numbers refer to cfm, Sones and
Bhp.
Example:
CFM
Sone Bhp
At this performance point, the sone value is 11.1 and
the fan Bhp required is 0.16. Now by following the row
to the left, we can determine fan rpm and fan model.
In this case, the fan rpm is 1510 and the model is
GB-090-4 which has a 1/4 hp motor.
Notice that the GB-090-4 is not the only model to
choose from. If we follow the 0.250 in. Ps column down
further, we find a performance point at 1010 cfm.
1012
11.1 0.16
exceptions to this rule. The selection procedure for
these models is handled separately. Direct drive and
belt drive fans are also addressed separately.
At this point, the sone value is 7.9 and the Bhp is 0.14.
Following across to the left we find the rpm to be 1355.
The model is GB-101-4-R1, which also has a 1/4 hp
motor.
Both the GB-090-4 and the GB-101-4-R1 will perform
the air movement task equally as well. However, the
sound generated by the fan may have to be
considered. Compare the sone values: 7.9 sones for the
GB-101 and 11.1 for the GB-090. The GB-101 is about
30% quieter. Where a low sound fan is required, the
GB-101 would be a better selection. If loudness is not a
factor, the GB-090 would be a better selection because
it is less expensive.
Another possibility for this particular selection is a
GB-100-4-R2. Even though there is no performance
box showing close to 1000 cfm, there are two
performance boxes that bracket 1000 cfm. At 921 cfm
the fan will be running at 1260 rpm. At 1269 cfm the fan
will be running at 1635 rpm. Therefore, there is an rpm
for this model that will correspond to 1000 cfm
(obviously somewhere within the 1260-1635 rpm
range). As with all Greenheck belt drive fans,
intermediate cfm values are easily achieved by
adjusting the motor pulley (see illustration on next
page).
Table 2
MODEL
(rpm RANGE)
GB-090-4
(1290-1710)
GB-101-4-R1
(1020-1400)
GB-101-4-R2
(1260-1635)
GB-101-3
hp
1/4
1/4
1/4
1/3
RPM
1360 3983
1510 4422
1710
1070 3116
1355 3946
1260
1635
1800 5242
TS
5008
3669
4761
STATIC PRESSURE / CAPACITY
0.000 0.125 0.250 0.375 0.500 0.625 0.750 0.875 1.000
Sone Bhp Sone Bhp Sone Bhp Sone Bhp Sone Bhp Sone Bhp Sone Bhp Sone Bhp Sone Bhp
1030
10.1 0.11 9.9 0.12 9.6 0.12 9.3 0.12 8.8 0.13 8.5 0.13
1144
0.15 11.2 0.16 11.1 0.16 10.7 0.17 10.4 0.17 10.0 0.17 9.8 0.17 9.5 0.17
11.4
1295 1237 1179 1121 1061 999 934 866 785
13.4 0.22 13.3 0.23 13.2 0.23 13.0 0.24 12.7 0.24 12.4 0.25 12.1 0.25 11.8 0.25 11.6 0.25
906
6.0 0.060 5.4 0.065 5.0 0.070 4.3 0.070
1148 1077 1010 943 856 739
0.12
8.5
1067 991 921 840 735 385
0.099 7.1 0.104 6.8 0.112 6.5 0.115 5.9 0.115 4.4 0.083
7.6
1385 1325 1269 1214 1161 1094 1019 928 792
11.1 0.22 10.8 0.22 10.4 0.23 10.2 0.24 9.8 0.25 9.3 0.25 8.9 0.25 8.4 0.25 7.8 0.24
1525 1471 1418 1367 1320 1270 1208 1141 1064
0.29
13.2
8.1
12.8
957
1078
818
0.13
0.30
884
1012 946 875 800 720 607
731
7.9 0.14 7.8 0.14 7.2 0.14 6.8 0.14
0.30
12.5
807
607
0.31 12.2 0.33 11.3 0.33 10.8 0.33 10.6 0.33 10.1 0.33
12.3
725
632
5
One advantage of choosing the GB-101-4-R2 over the
GB-101-4-R1 is that it is capable of running at higher
rpm’s, which enables the fan to move more air if
necessary.
Motor pulleys are adjusted by loosening the set screw
and turning the top half of the pulley (see illustrations at
right). This causes the pulley diameter to change, which
results in changing the fan rpm.
Direct Drive Selection
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.
1. 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 slows it down; a principle similar to
the way dimmer light switches work.
Belt
Opening the pulley decreases fan rpm.
Closing the pulley increases fan rpm.
2. 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 3 speed motors, 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.
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
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.
Accessories
Most fans are ordered with accessories. Here are some common accessories for selected models:
Model Common Accessories
G & GB
CUBE
SB
Roof Curb
Backdraft Damper
Roof Curb
Grease Trap
Wall Mount Housing or
Wall Mount Collar
Model Common Accessories
SP & CSP
SQ & BSQ
Speed Control
Discharge Vents
Backdraft Damper
Vibration Isolators
6
Matching a Specification
There will be times when a Greenheck model will have
to be matched to a competing manufacturer’s unit. To
aid in these circumstances, we have provided a cross
reference chart which includes our nine most common
competitors. If the manufacturer you need is not on this
chart, contact Greenheck for assistance.
To use the cross reference chart, on next page, start
with the manufacturer at the top. Then follow down
until the model in question is found. Follow across to
the left to determine which Greenheck model is
equivalent. Once this is determined, refer to the
Greenheck catalog to find the best size to meet the
specified performance.
Hint: Typically, when matching a Greenheck fan to a
competitive model, the size should also be matched. If
you are unsure of the size of the competitive unit,
compare fan rpm. Fans of equal size should move
approximately the same amount of air.
Model RSF and BCF Selection
The RSF and BCF selection charts are different from all
other selection charts. For these models, the cfm
values are at the left side of the chart in a single column
and the rpms are in the performance boxes. It is just the
opposite for other models. The reason for this is that
the RSF and BCF models are forward curved, and the
fan industry historically catalogs forward curved fans in
this fashion.
Sample problem:
Choose the fan size and appropriate motor horsepower
to move 980 cfm against 0.625 in. Ps.
Solution: (Refer to table below)
The first row in the chart corresponds to 980 cfm.
Follow across to the right to the 0.625 in. Ps column.
The performance box reveals that size 90 will meet this
performance at 893 rpm and will require 0.20 Bhp.
Motor hp selection for forward curved fans is more
complicated. The Bhp is only 0.20, which suggests that
a 1/4 hp motor is adequate. However, forward curved
fans draw more horsepower at low Ps than at high Ps.
Assume this fan was running at about 893 rpm, but
instead of 0.625 in. Ps, it was operating at only 0.25 in.
Ps. The new performance box in the 0.25 in. Ps column
reveals 894 rpm at 0.45 Bhp. The airflow would then be
1860 cfm.
Notice that as the Ps was reduced from 0.625 in. to 0.25
in., the Bhp increased from 0.20 to 0.45. This would
burn out the 1/4 hp motor quickly. With this in mind, it is
good practice to size RSF and BCF motors at least one
size larger than necessary based on the Bhp value in
the performance box, especially if the estimated Ps is
questionable.
For this case, an RSF-90-3 (1/3 hp motor) would be a
good selection if we had confidence in the estimated
Ps. Otherwise, use an RSF-90-5 (1/2 hp motor).
RSF-90-4 (1/4 hp motor) is not recommended for this
job.
MODEL
RSF-90
RSF-100
CFM
980 1065
1200
1420 1543
1640 1783
1860 2022
2080 2261
1240 1097
1780
2140
OV
1304
1575
1894
rpm
Bhp
rpm
Bhp
rpm
Bhp
rpm
Bhp
rpm
Bhp
rpm
Bhp
rpm
Bhp
rpm
Bhp
rpm
Bhp
STATIC PRESSURE / CAPACITY
0.125 0.250 0.375 0.500 0.625 0.750 1.000 1.250 1.500 1.750
521 630 725 812 893 967
0.08 0.11 0.13 0.16 0.20 0.23
593 685 771 849 925 994 1125
0.13
668
0.19 0.23 0.27 0.31 0.35 0.39 0.48 0.57 0.67
746 819 887 953 1016 1077 1191 1298
0.28
828 894 954 1014 1073 1128 1236
0.40 0.45 0.50 0.55 0.60 0.65 0.76
910 970 1027 1080 1134
0.54 0.60 0.66 0.71 0.77
476 572 656 733 807 876
0.10
605 679 748 813 873 931 1040 1143 1240
0.24 0.29 0.33 0.38 0.42 0.47 0.56 0.66 0.77
699
0.40 0.45 0.50 0.56 0.61 0.67 0.78 0.89 1.00 1.12
0.16 0.19 0.23 0.26 0.30 0.38
747
0.33
0.13
763
825
0.37
0.16
823 880 935 989 1086 1181 1269 1354
898
0.42 0.46 0.51 0.61 0.71
0.19
966
0.23
1031
0.27
1153
1267 1371
7
Cross Reference Chart
(Models in italics refer to older models)
Greenheck
G
CE,CX,CH
GB
CDE, CBX
Cook
Updated 12-7-2004
ACED
C-D,CVD,TCD
ACEB
C-B,TCB,UCB
Penn Acme
Domex DX
XQ,XR,AT,AW
Domex DXB
KB,JB,MB,AB,LB
PRN CRD VEDK
PN,PNN,PV NBCR
CUE ACRUD, VCRD Fumex FX PDU n/a VUDK CUD, UBD n/a DU
CUBE
UCBE,UCBH
CW
SW,GW
CWB
GWB
ACRUB,VCR
URB,R-B,BTD
ACWD
CW
ACWB
CWB,TWB
SP Gemini GC Zephyr
CSP Gemini Inline GN Zephyr
SQ
DSQ,SQD
SQID,SQND
CV-D
BSQ SQIB,SQNB,
Fumex FXB
FMXB
Fumex WFX
Domex
WX,WA,WB
Fumex WFXB
Domex WCB,WLB
PNU
PUB,PU,PUH
PDU-W
PW
PNU-W
PWB
VQ/VQL J,EC,L VCDB,VCDC,
Z, (RA,TD)
VQ/VQL n/a VCDB IL DCF n/a
Z, (TDA)
Centrex SX XD ISD
Centrex SX-BC XB ILB VIBK
SQN-HP
SE/SS
SDE
SWD
SD
P FQ GDW
SCE/SCS AWD BC FN n/a LRDA,LNDA CDC HV, HVE
SBE/SBS
SPFE/SPFS
SBE/SBS-3
SPNE/SPNS
XLW,XMW
SWB SPB
BBK,BFL DC TBW LWBK,LMBK
XLWH,XMWH BF DCH LBW LJDB, LKDB,
SBCE/SBCS AWB BC,BAT DCK, K HBW LRBA,LNBA CBC HA
RBS/RBE
RPE,RPS
HXSL, HXSM,
HXEL, HXEM
AF EC/EC-S n/a LTBA,LGBA PB n/a n/a
RBCE/RBCS HEE,HES AC EC, ECH HBRE,HBRS n/a PBC n/a n/a
RE/RS HEE-D/HES-D AF n/a n/a LTDA,LGDA PD n/a n/a
RBU
PBU,PUB
LEU, LXUL, LXUM
AVB,VB
HF,HS,HZ
(cast)
UBG BRU LUBA JBH,JBC
RBUMO SUBH, SUB HX UBH available LUKA n/a RUBDX
RDU AUD HZ,HC UD DRU LUDA JDC UP
RSF ASP
CFS
Muffan MU AFSN
PLS
RSFP ASP-T n/a AFSL n/a VHBB n/a n/a n/a
SFD CPF-D n/a FCE FCD n/a n/a UDF n/a
SFB CPF-B n/a FCF, FCD,
FCA
SWB CPV,CPS Dynamo D,QX
GWB
QBR JVS VBBA VSBC UXB BI
Jenn
(Breidert)
(Stanley)
Carnes
VEDB,VEDC
VEBK
BCR
NBTD
NBRTD
VEBC
VUBK,VRBK
VUBB,URBA
CWD VWDK
VWDB
NBTD
NBRTD (UL 762)
VWBK
VWBB
VCDD
VIDK
ILD
VIDB,AMDA
COOLAIR
(ILG)
AirMaster
(Chelsea)
CRD CDD
RDD
CRB
LSB
UBC,CUB
CVB
CWD
CWF
CBD
RDB
CBU
CUBA
CDU
WDC
CWB CBU
WBC
CF NCF
CF
SQDA
CLD
n/a CVIDK
Captive Aire
DR
DD
NCA
DU
NCA
CFA
SQBA SBCL CVIBK
VIBA
HDW,FDW
LYDK,LZDK
LWDA
UDU/UDFPVEPR
WFA
C-EPR
n/a
PLFA
TYPE T
CBL,CBHPFHA
IND, FHA
CPB
CBHX n/a n/a
LRDA, LNDA
n/a
IND
(cast)
UPB
RUBA
CUPB
n/a
(cast)
CUPD
RUDA
BCFS VSBB
VSBA
CFS CAS n/a
FCB VFBA VSFC UXF n/a
(Flow Air)
Competitor Model Number Deciphering Hints
Cook-
Direct Drive
120 W 10 D
Direct Drive
rpm x 100
Model ACW
Wheel Size
Letter Designations
C=ACE (G,GB)
R=ACRU (CUBE)
W=ACW (CW,CWB)
V=VCR (CUBE)
Belt Drive
150 V 6 B
Belt Drive
3/4 hp
Model VCR
Wheel Size = 15 in.
Horsepower Designations
/4
3
=1/6 hp
2
3=1/4
4=1/3
=1/2
5
=
6
7=1
8=1
=
9
1
/2
2
8
=
0
1
11=5
12=7
Acme -
Direct Drive
PW 135 A 8
860 rpm
1/20 hp
Wheel Size =13.5 in.
Model PW
Direct Drive rpm Designation
3
1
/2
8 = 860 rpm
6 = 1160 rpm
4 = 1725 rpm
Belt Drive
PNN 163 G
1/2 hp
Wheel Size = 16.3 in.
Model PNN
Horsepower Designation
1/20 hp
=
A
B=1/12
C=1/8
1/6
=
D
E=1/4
=
F
G=1/2
H=3/4
=
J
K=1
1/3
1
2
=
L
M=3
N=5
1
7
=
/2
P
1
/2
R=10