Reznor RXH (Outdoor PreevA) Unit Installation Manual - Manual (Page 47)

Form I-RDH/REH/RHH/RXH (12-14), P/N 215210 R14, Page 47
7.5.2 Reverse Airflow
Limit Control - RDH/
RHH
7.5.3 Combustion Air
Pressure Switch (Air
Proving Switch) - RDH/
RHH
NOTE: Above 6000 ft
(1830 M) elevation, a high
altitude pressure switch may
be required. See Paragraph
6.1.3.
DANGER
Models RDH and RHH proper venting flow. NEVER bypass combustion air proving switch(es)
or attempt to operate the unit without the venter running and proper flow in the vent system.
Hazardous conditions could result. See Hazard Levels, page 2.
RDH
Size
High Speed Low Speed
(applies only to units with gas controls*
using a 2-speed venter)
Applies to ALL gas control options
EXCEPT AG58 & D12G
Applies to gas control options
AG58 & D12G
Switch P/N Setting (" w.c.) Switch P/N Setting (" w.c.) Switch P/N Setting (" w.c.)
75 197030 0.40 N/A 205442 0.20
100 197030 0.40 N/A 205444 0.30
125 196388 0.50 N/A 205444 0.30
150 197028 0.65 N/A 205444 0.30
175 201158 1.10 197029 0.60 197030 0.40
200 201158 1.10 197078 0.80 197030 0.40
225 201158 1.10 197078 0.80 197030 0.40
250 201158 1.10 207171 0.70 197030 0.40
300 201158 1.10 207171 0.70 197030 0.40
350 201158 1.10 197078 0.80 197030 0.40
400A 201158 1.10 207171 0.70 197030 0.40
*Gas Control Options with 2-speed venter are AG8, AG9, AG9H, AG40, AG60, AG61, AG62, DG1, DG2, DG5, DG6, D12B, and D12C.
TABLE 30A - Model RDH Pressure Switch Settings
TABLE 30B - Model
RHH Pressure Switch
Settings
RHH
Size
High Speed
Applies to ALL gas control options
EXCEPT AG58 & D12G
Applies to gas control options
AG58 & D12G
Switch P/N Setting (" w.c.) Switch P/N Setting (" w.c.)
130 201161 1.30 201160 1.05
180 201161 1.30 201160 1.05
260 201159 1.40 201160 1.05
350 221228 2.30 201160 1.05
All units are equipped with a temperature activated auto reset reverse airflow limit con-
trol. The control is factory set and is non-adjustable. If the setpoint is reached, the limit
control will interrupt the electric supply to the gas valve. This safety device provides
protection in the case of motor failure or lack of airflow due to a restriction at the outlet.
The combustion air proving switch is a pressure switch that monitors air pressure to
ensure that proper combustion airflow is available. The switch is a single pole/normally
open device which closes when a negative pressure is sensed in the venter housing.
On startup when the heater is cold, the sensing pressure is at the most negative level,
and as the heater and flue system warm up, the sensing pressure becomes less nega-
tive. After the system has reached equilibrium (about 20 minutes), the sensing pres-
sure levels off.
If a restriction or excessive flue length or turns cause the sensing pressure to be out-
side the switch setpoint, the pressure switch will function to shutoff the main burner.
The main burner will remain off until the system has cooled and/or the flue system
resistance is reduced.
TABLE 30 lists the switch setpoints for sea level operating conditions.
Models equipped with two-speed venter motor operation have two combustion air prov-
ing switches. When the venter is operated at high speed, the “high speed” combustion
air proving switch monitors the combustion airflow to ensure adequate airflow for safe
and efficient operation. During low speed venter operation, when fuel gas input rate is
reduced, a second “low speed” combustion air proving switch monitors the combustion
airflow to ensure adequate air flow for safe and efficient operation.
7.5.4 Blower Motor
(RDH/REH/RHH/RXH)
and Venter Motor (RDH
and RHH)
Use an ammeter to check blower motor amps. Amps may be adjusted downward by
reducing blower RPM or by increasing duct system static pressure (See Paragraph
6.9.2.)
TABLE 31 lists full load amps of open-type blower motors by HP and voltage. This
chart can be used for sizing line wiring but should not be interpreted as the exact motor