TABLE 3
Curb Outside Dimensions

ROOF CURB MOUNTING

1.Factory Supplied Roof Curbs

Roof curbs are Model GKD, which are shipped in a knockdown kit and require field assembly (by others). Assembly instructions are included with the curb.

2.Cut Roof Opening and Locate Curb

Layout the unit roof opening such that the supply discharge & exhaust inlet of the unit will line up with the corresponding ductwork (refer to Recommended Roof Openings on page 3). Be sure to allow for the recommended service clearances. Keep the supply inlet of the unit away from any other exhaust fans.

3.Install Curb

Locate curb over roof opening and fasten in place.

Check that the diagonal dimensions are within ±1/8 inch of each other and adjust as necessary. Shim as required to level. Lower unit onto curb by following the LIFTING instructions on page 3 of this manual. Note,

roof curbs fit inside the unit base.

4. Install Duct Work

Model

L

W

 

 

 

Installation of all

 

 

 

ERH-20

73

51

ducts should be

 

 

 

ERH-45

80.75

60.63

done in accordance

 

 

 

ERH-55

94

71.5

with SMACNA and

ERH-90

106.25

90.75

AMCA guidelines.

Dimensions shown are in inches.

L

W

FIGURE 3

Roof curb details, including duct location dimensions, are available on ERH roof curb submittals.

DUCT WORK CONNECTIONS

Examples of good and poor fan-to-duct connections are shown below (See FIGURE 4). Airflow out of the fan should be directed straight or curve the same direction as the fan wheel rotates. Poor duct installation will result in low airflow and other system effects.

R

 

 

tio

 

a

t

 

o

 

 

n

Length of Straight Duct

 

 

 

tion

 

 

a

 

 

t

 

 

R

o

 

 

 

 

 

 

GOOD

TABLE 4

 

 

 

FIGURE 4

 

 

 

 

 

 

Recommended Discharge

 

 

Duct Size and Length

 

 

 

 

 

ERH

 

ERH

Duct

Straight

 

Blower

Duct

Model

Size

Size

Length

 

 

 

 

 

 

 

 

20

 

10

14 x 14

40

45

 

12

20 x 20

48

55

 

15

28 x 28

60

90

 

18

32 x 32

72

Dimensions shown are in inches.

POOR

4

Page 4
Image 4
Greenheck Fan ERH-55, ERH-45, ERH-90, ERH-20 manual Roof Curb Mounting, Duct Work Connections