Electrical supply and connections, Control thermostat – Reznor SCE Unit Installation Manual User Manual

Page 20

Form RZ-NA I-SCE, Page 20

11. Electrical Supply

and Connections

All electrical wiring and connections including electrical grounding must be made in accor-

dance with the National Electric Code ANSI/NFPA No. 70 (latest edition) .

Check any local ordinances or gas company requirements that apply.
Check the rating plate on the heater for the supply voltage and the current requirements. 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 junction box. Refer to

FIGURE 1,

Paragraph 3. Seal all electrical entrance openings with field-supplied bushings.

A disconnect switch is available as optional equipment or may be supplied locally. When

installing the disconnect switch, be careful that the conduit and switch housing are clear of

all service panels. Allow at least four feet (1.2M) of service room between the disconnect

switch and any removable service panels. When providing or replacing fuses in a fusible

disconnect switch, use dual element time delay fuses and size 1.25 times the maximum total

input amps.
The heater is equipped with a low voltage (24V) control circuit. See the typical wiring dia-

grams on pages 21 and 22; a specific wiring diagram can be found in the heater junction box.

See separate instruction sheets for any optional equipment provided. Optional equipment is

identified on the wiring diagram supplied with the heater.

Field Control Wiring - Length and Gauge

Total Wire

Length

Distance from

Unit to Control

Minimum Recommended

Wire Gauge

150ft (46M)

75ft (23M)

#18 gauge

250ft (76M)

125ft (38M)

#16 gauge

350ft (107M)

175ft (53M)

#14 gauge

CAUTION: If any of the

original wire as supplied

with the appliance must be

replaced, it must be

replaced with wiring

material having a

temperature rating of at

least 105°C, except for

sensor lead and optional

bypass damper combustion

air safety circuit (Option

AG39 or AG40) wires

which must be 150°C. See

Hazard Levels, page 2.

Voltage/Phase

Motor HP

Wire Gauge

BX Cable

120/1

1/4 - 1/2

3/8"

208-230/1

1 - 1-1/2

3/8"

208-230/3

1/4 - 3

3/8"

460/3

1/4 - 5

3/8"

575/3

1/2 - 5

3/8"

Field-Supplied Wiring Size from Disconnect to Electrical Box for

Connection to Motor Contactor or Starter

12. Control

Thermostat

A thermostat is not supplied with the furnace. Use either an optional or a field-provided low-

voltage (24V) thermostat. Install the thermostat according to the manufacturer's instruc-

tions.
A low voltage thermostat is equipped with a heat anticipator which levels out unit cycling for

optimum temperature control. Set the anticipator at 1.0 amps for standard controls. See chart

below for amp ratings of optional controls.

CAUTION: Control circuit amps should be within the anticipator amp

rating of the thermostat used.

Ampere Rating of 24-Volt Controls

Fan Control ...............................

.12 amps

Time Delay Heater .....................

.14 amps

RBM Relay Coil .........................

.12 amps

Contactor Coil ...........................

.45 amps

Spark Ignition System............... .1 amps

Maxitrol Gas Control System .... .51 amps

Honeywell Gas Valve ................ .5 amps

White-Rodgers Gas Valve .. ....... .6 amps