Reznor RXH (Outdoor PreevA) Unit Installation Manual - Manual (Page 43)

Form I-RDH/REH/RHH/RXH (12-14), P/N 215210 R14, Page 43
6.9.3 Blower Rotation
Rotation may be changed on single-phase motors by re-wiring in the motor terminal
box. Three-phase motors may be reversed by interchanging two wires on the 3-phase
supply connections.
6.9.4 Optional Variable Frequency Drive (VFD)
If ordered with a VFD, it may be either factory or field
installed. If field-installed, follow the manufacturer’s instruc-
tions and refer to the wiring diagram on the unit. Minimum
ambient temperature for a VFD is 18°F. Maximum distance
from the unit is 50 feet.
When an optional VFD is ordered, the motor operates on
two speeds as determined by the electrical frequency.
High speed is used for cooling and low speed for heating.
60 hertz is the maximum high speed. Maximum speed for
low speed heating is the frequency that will provide the
maximum temperature rise of the heater.
Maximum allowable temperature rise for a Model RDH is
70°F with an aluminized heat exchanger or 100°F with a
stainless steel heat exchanger. ( NOTE: If equipped with
modulating gas control Option AG40, AG58, DG2, DG6,
D12B, or D12G and a stainless steel heat exchanger, a
maximum temperature rise of 120°F is permitted.)
Follow the VFD controller manufacturer’s instructions that
are packaged with the heater (in the owner’s envelope) to
program the VFD settings. The formula for motor speed is
N=120xf/p where N is speed; f is frequency; and p is num-
ber of poles (3600 RPM motor has 2 poles; an 1800 RPM
motor has 4 poles).
Example: 1800 RPM motor on 60Hz; N = 120 x 60/4 =
1800
1800 is synchronous speed; assume 2% slip.
Motor will run between 1750
and 1790 RPM at full load depending on design.
Run the same motor at 45Hz (120 x 45/4
= 1350). 1350 RPM
less 2% slip equals about 1300 RPM.
7.0 Electrical Supply
and Wiring
7.1 General
All electrical wiring and connections including electrical grounding must be made in
accordance with the National Electric Code ANSI/NFPA No. 70 (latest edition) or, in
Canada, the Canadian Electrical Code, Part I-C.S.A. Standard C22.l. Check any local
ordinances or utility company requirements that apply.
Check the rating plate on the heater for the supply voltage and the current require-
ments. A separate line voltage supply with fused disconnect switch should be run
directly from the main electrical panel to the unit, making connections in the electrical
compartment. Supply wiring enters the cabinet either on the control side below the
electrical compartment door or in line directly below through the base. Seal all electri-
cal entrance openings with field-supplied bushings.
Before turning on the power, check and tighten all electrical terminals.
7.2 Supply Wiring
NOTE: If the system has an
optional convenience outlet
or UVC light, both of those
options require a separate
115 volt power supply.
Field-Supplied Wiring Size - Models RDH, RHH, and RXH
Voltage/Phase 115/1 208-230/1 208-230/3 460/3 575/3
Motor HP's 1/4 - 1/2 1 1 - 1-1/2 1/4 - 3 5 1/4 - 5 1/2 - 5
Wire Gauge 14 12 14 14 12 14 14
BX Cable 3/8" 3/8" 3/8" 3/8" 3/8" 3/8" 3/8"
TABLE 27A - Supply
Wiring Size - Models
RDH, RHH, and RXH
Field-Supplied THHN, THWN or THWN-2 Wiring and Conduit Minimum Size for Model REH
Voltage/Phase 208/1 230/1
KW 10 15 20 30 10 15 20 30
Ampacity 74 96 119 164 78 104 130 182
75°C Wire Gauge #4 #3 #1 #2/0 #4 #2 #1 #3/0
Conduit Trade Size 1 1 1-1/4 1-1/2 1 1 1-1/4 2
Voltage/Phase 208/3 230/3
KW 20 30 40 60 80 90 120 20 30 40 60 80 90 120
Ampacity 66 92 118 142 184 205 267 74 104 134 161 209 233 305
75°C Wire Gauge #4 #3 #1 #1/0 #3/0 #4/0 300kcmil #4 #2 #1/0 #2/0 #4/0 250kcmil 350kcmil
Conduit Trade Size 1 1-1/4 1-1/2 1-1/2 2 2 2-1/2 1 1-1/4 1-1/2 2 2 2-1/2 3
Voltage/Phase 460/3 575/3
KW 20 30 40 60 80 90 120 20 30 40 60 80 90 120
Ampacity 37 52 67 81 105 117 153 31 44 56 67 88 98 128
75°C Wire Gauge #8 #6 #4 #4 #2 #1 #2/0 #10 #8 #6 #4 #3 #3 #1
Conduit Trade Size 3/4 3/4 1 1 1-1/4 1-1/2 2 1/2 3/4 3/4 1 1-1/4 1-1/4 1-1/2
TABLE 27B -
Supply
Wiring Size -
Model REH
7.2.1 Supply Voltage The electric supply to the unit must meet stringent requirements for the system to oper-
ate properly. Voltage supply should be within ±10% or as stated on the rating plate.
Maximum imbalance on a 3-phase system is 2%. Follow instructions below to check.