Reznor RPB Unit Installation Manual - Manual (Page 29)

Form I-RPB, P/N 131782 R12, Page 29
7.5.6 Blower Motors Use an amp meter to check motor amps. The following chart lists full load amps for
various HP's and voltages. Amps may be adjusted downward by reducing blower RPM
or increasing duct static pressure.
This chart can be used for sizing line wiring but should not be interpreted as the exact
motor amps.
See the motor rating plate for exact motor specifications.
Full Load Amps - Blower Motors (Open)
(Single Speed- Average Values)
HP 1/4 1/3 1/2 3/4 1 1-1/2 2 3 5
208V 1PH 2.1 3.2 5.1 6.3 7.5 8.3 11.3 14.0 28.0
230V 1PH 2.3 2.8 4.4 5.5 6.5 7.5 10.2 12.4 26.0
208V 3PH 1.1 1.4 2.3 2.9 3.7 5.6 7.0 9.0 13.4
230V 3PH 1.4 1.6 2.0 2.6 3.2 5.0 6.6 8.6 13.2
460V 3PH .75 .80 1.0 1.3 1.6 2.7 3.5 4.3 6.6
575V 3PH N/A N/A N/A N/A 1.1 1.6 2.1 3.6 5.4
8.0 Controls
8.1 Gas Controls
8.1.1 Gas Valve
All furnaces are equipped with a 24-volt combination gas valve which includes the
automatic electric on-off valve controlled by the room thermostat, the pressure regula-
tor, the safety pilot valve, and the manual shutoff valve. The standard gas valve allows
for single-stage control from a single-stage, 24-volt thermostat.
7.5.3 Limit Control
7.5.4 Combustion Air
Proving Switch
The combustion air proving switch ensures that proper combustion airflow is avail-
able. The switch is a single-pole, double-throw switch, which senses pressure caused
by the flow of combustion air from the venter. The switch is designed to close when a
decreasing pressure is sensed in the outlet duct of the gas collection box. For location,
see FIGURE 29, Item 2.)
On start-up when the furnace is cold, the sensing pressure is at the most negative
level, and as the furnace and the flue system warm-up, the sensing pressure becomes
less negative. After the system has reached equilibrium (approximately 20 minutes),
the sensing pressure levels off. If a restriction or excessive flue length or turns cause
the sensing pressure to become less than the switch setpoint, the pressure switch will
function to shut off the main burners. The main burners will remain off until the sys-
tem has cooled and/or the flue system resistance is reduced. The table below gives
approximate water column negative pressure readings and switch setpoints for sea
level operating conditions.
Startup Cold Equilibrium Factory Setpoint
-1.05" w.c. -.73" w.c. -.58 ± .05" w.c.
DANGER
Safe operation requires proper venting flow. Never bypass the combustion air proving
switch or attempt to operate the unit without the venter running and proper flow in the vent
system. Hazardous condition could result. See Hazard Levels, page 2.
7.5.5 Optional High
Ambient Limit
Heaters are equipped with a non-adjustable high limit switch which shuts off the gas
in the event of motor failure, lack of air due to dirty filters, or restrictions at the inlet or
outlet of the unit. For location, see FIGURE 29, Item 11.
The optional high ambient limit control functions to shutoff the burner when the enter-
ing outside air reaches a set temperature. The temperature setting is field adjustable
from 0-100°F. For location, see FIGURE 29, Item 21.
WARNING
The operating valve is the prime safety shutoff. All gas supply lines must be free of dirt or
scale before connecting the unit to ensure positive closure. See Hazard Levels, page 2.
8.1.2 Optional
2-Stage Operation -
Heating Only
The standard combination control valve is replaced with a two-stage combination gas
control valve providing for low fire or high fire operation controlled by a two-stage
thermostat. First stage (low fire) is factory set (not field adjustable). Both high and low
stages are controlled by a Servo regulator, maintaining constant gas input under wide
variations in gas supply pressure. See instructions packed with the unit for specific gas
valve specifications, wiring, and operating instructions.