4 blowers, drives, and motors, 0 mechanical (cont'd) – Reznor RDF Unit Installation Manual User Manual
Page 16
I-RDF, PN148384R5, Page 16
6.0 Mechanical
(cont'd)
6.4 Blowers, Drives, and Motors
Belt Tension - Check belt tension. Proper belt tension is important to the long life
of the belt and motor. A loose belt will cause wear and slippage. Too much tension
will cause excessive motor and blower bearing wear. If adjustment is required, adjust
belt tension by means of the adjusting screw on the motor base until the belt can be
depressed 1/2" to 3/4" (
FIGURE 12). Tighten the lock nut on the adjusting screw. Be
sure the belt is aligned in the pulleys.
3/4 (19mm)
FIGURE 12 - Belt
Tension
Motor and Belt Shipping Position for Sizes 2-80, 2-120, 3-180, 3-260 - To relieve
tension on the motor mounting bracket, the belt(s) are taken off the motor and blower
sheaves before shipping. The belt(s) are taped to the blower shaft to prevent loss or
damage during shipment. Install the belt(s) and adjust for proper belt tension.
Blower Pulley - Size 2-80 and 2-120 systems equipped with 3 and 5 HP motors with
a 15.4" diameter and larger blower pulley or a 7-1/2 HP and larger motor and all Size
3-180 and 3-260 systems are equipped with a split taper bushing in the blower pulley.
The split taper bushings must be loosened in order to remove the pulley. Follow these
instructions to loosen the bushing.
1) Notice that there are three cap screws in the bushing and two holes without
screws, called push-off holes (See
FIGURE 13).
2) Remove the three cap screws.
3) Put two of the cap screws into the two push-off holes. Tighten these two screws
evenly until the pulley is loosened.
4) Pulley may now be removed from the shaft.
Blower Speed Adjustment - Units are set at the factory for the RPM required to meet
the CFM and external static pressure specified on the order. If the estimated external
static is incorrect, or changes are made to the duct system, the blower RPM may have
to be changed. Motors are equipped with adjustable pitch pulleys which permit adjust-
ment of blower speed. Instructions are included in Paragraph 9.0, Check-Test-Start for
adjusting blower speed.
Blower Rotation - Each blower housing is marked for proper rotation. Instructions for
checking blower rotation are included in the startup procedures in Paragraph 9.0.
Motor Loads - Use an ammeter to check motor amps. Amps may be adjusted down-
ward by reducing blower RPM or by increasing duct system static pressure. For accu-
rate amps, read the motor manufacturer's rating plate; amps will vary depending upon
motor manufacturer. The chart below can be used for sizing line wiring.
3 Cap
Screws
FIGURE 13 - Split
Taper Bushing
2 Push-Off Holes
CAUTION: The motor amp chart lists full load amp requirement
of standard motor and standard controls. Optional controls
will increase amp requirement. Add motor amps and control
amps for approximate unit full load amps. System FLA is
shown on the rating plate.
Blower Motor Full Load Amps (open motors)
Motor HP
115V/1
230V/1
208V/3
230V/3
460V/3
575V/3
1/2
9.8
4.9
2.2
2.0
1.0
N/A
3/4
13.8
6.9
3.1
2.8
1.4
N/A
1
16.0
8.0
4.1
3.6
1.8
1.4
1.5
N/A
10.0
5.75
5.2
2.6
2.0
2
N/A
N/A
7.5
6.8
3.4
2.4
3
N/A
N/A
10.6
9.6
4.8
3.6
5
N/A
N/A
16.8
15.2
7.6
5.4
7.5
N/A
N/A
21.0
19.0
9.5
8.4
10
N/A
N/A
29.0
25.2
12.6
10.4
15
N/A
N/A
42.0
40.0
20.0
16.0
20
N/A
N/A
53.0
50.0
25.0
20.0
25
N/A
N/A
66.0
63.0
31.5
26.0
30
N/A
N/A
78.0
74.0
37.0
28.5