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

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