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Roof curb mounting, Curb outside dimensions and weights, Curb outside dimensions – Greenheck Fan 455924 ERV-522 User Manual

Page 5: Ductwork connections

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5

Energy Recovery Ventilator

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Length of Straight Duct

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Roof Curb Mounting

Roof curb details including duct location dimensions,
are available on ERV-522 & 582 Roof Curb Assembly
Instructions, Part #460988.

Rooftop units require curbs to be mounted first. The
duct connections must be located so they will be
clear of structural members of the building.

1. Factory Supplied Roof Curbs: Roof curbs are

Model GPI or GPNS for the ERV-251, 361, 521,
581. The GPI or GPNS ships assembled and
includes a duct adapter.

Roof curbs are Model GKD for the ERV-522 and

582. The GKD ships in a knockdown kit (includes
duct adapter) and requires field assembly (by
others). Assembly instructions are included with
the GKD curbs.

2. Install Curb: Locate curb over roof opening and

fasten in place. (Refer to Recommended Roof
Openings). Check that the diagonal dimensions
are within ±1/8 inch of each other and adjust
as necessary. For proper unit operation, it is
important that the installation be level. Shim as
required to level.

3. Install Ductwork: Installation of all ducts should

be done in accordance with SMACNA and AMCA
guidelines. Duct adapter provided to support
ducts prior to setting the unit.

4. Set the Unit: Lift unit to a point directly above

the curb and duct openings. Guide unit while
lowering to align with duct openings. Roof curbs
fit inside the unit base. Make sure the unit is
properly seated on the curb and is level.

Unit Size

L

W

Curb Weight (lbs.)

ERV-251

42.5

30.5

60

ERV-361

58.5

47.5

115

ERV-521

63.5

63.5

160

ERV-581

71.8

66

185

ERV-522

120.5

80.5

520

ERV-582

142.25

93

700

All dimensions are in inches. Weights are for 12-inch high
GPI type curbs.

W

L

ERV-251, 361, 521 and 581

W

L

ERV-522 and 582

Curb Outside Dimensions and Weights

Roof Curb

Side of Unit

Base

1-inch Insulation

E

D

C

A

B

Unit Size

A

B

C

D

E

ERV-251

1.75

2.00

1.00

1.125

0.750

ERV-361

1.75

2.00

1.00

1.200

0.875

ERV-521

1.75

2.00

1.00

0.813

0.875

ERV-581

1.75

2.00

1.00

0.813

0.750

ERV-522

1.813

4.00

1.75

1.000

0.750

ERV-582

1.938

4.125

1.938

1.125

0.625

All dimensions are in inches.

Curb Cap Details for Factory Supplied Roof Curbs

Curb Outside Dimensions -

continued

Recommended Discharge Duct Size and Length

Model

Blower Size Duct Size Straight Duct Length

ERV-251

10

9 x 9

36

ERV-361

10

14 x 14

36

ERV-521

12

20 x 20

36

ERV-581

15

28 x 28

60

ERV-522S

15

28 x 28

60

ERV-522H

18

32 x 32

60

ERV-582

20

34 x 34

72

All dimensions shown in inches.

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cfm range of each model at approximately 800 feet per minute
(FPM) at minimum airflow and up to 1600 fpm at maximum
airflow. Recommended duct sizes are only intended to be a
guide and may not satisfy the requirements of the project.
Refer to plans for appropriate job specific duct size and/or
velocity limitations.

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duct length requirements as prescribed in AMCA Publication
201. Calculated values have been rounded up to nearest foot.

Ductwork Connections

Examples of poor and good fan-to-duct connections
are shown. 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.

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