Reznor RPB Unit Installation Manual - Manual (Page 33)

Form I-RPB, P/N 131782 R12, Page 33
8.2 Pilot and
Ignition
Systems
Flash Carryover
FIGURE 34 - Burner
Rack with Spark Pilot
Main
Burner
Spark Pilot
The horizontal pilot is located in the control end of the burner rack and is accessible
after the control compartment panel has been removed. All pilots are target type with
lint-free feature. Pilot gas pressure should be the same as supply line pressure. (See
Paragraph 6.1.) If required, adjust the pilot flame length to approximately 1-1/4" with
pilot adjustment screw in control valve body.
Intermittent Spark Ignition Safety Pilot Systems - There are two types of intermit-
tent spark pilots -- one type shuts off the pilot gas flow between the cycles and the
other not only shuts off the pilot gas flow between cycles but also has a lockout device
that stops the gas flow to the pilot if the pilot fails to light in 120 seconds. This lockout
feature has a 1-hour retry or requires manual reset by interruption of the thermostat
circuit. Propane units installed in Canada require the spark ignition system with the
lockout device. Refer to the wiring diagram supplied with the heater for pilot system
identification and wiring. Spark pilot without lockout is designated as Option AH2; with
lockout is Option AH3.
CAUTION: Due to high voltage on pilot spark wire and pilot elec-
trode, do not touch when energized. See Hazard Levels, page 2.
Service NOTE: If replacing an
earlier model of ignition controller,
order replacement kit P/N 257472
for a unit with recycling gas control
Option AH2 or P/N 257473 for
Option AH3 gas control with lock-
out. (Option codes are listed on the
unit wiring diagram.)
Recycling Ignition
Controller, UTEC 1003-638A,
P/N 257009, for Option AH2
Gas Control
Ignition Controller with
Lockout, UTEC 1003-514,
P/N 257010, for Option AH3
Gas Control
FIGURE 35 - Ignition
Controller
Ignition Controller - As part of the intermittent safety pilot systems, the ignition con-
troller provides the high voltage spark to ignite the pilot gas and also acts as the flame
safety device. After ignition of the pilot gas, the ignition controller electronically senses
the pilot flame. A low voltage DC electrical signal is imposed on the separate metal
probe in the pilot assembly. The metal probe is electrically insulated from ground. The
pilot flame acts as a conduction path to ground completing the DC circuit and proving
pilot flame. Proper operation of the electronic spark ignition system requires a
minimum flame signal of .2 microamps as measured by a microampmeter. With
pilot flame proven, the ignition controller energizes the main gas valve.
Flame Sensing Probe
Pilot
Orifice
Centerline of
first burner
High Tension
Lead
Burner
Rack
Front
Spark Electrode
Spark Gap
7/64” (2.78mm)
TOP VIEW OF BURNER
TOP
VIEW
SIDE
VIEW OF
PILOT
1/4”± 1/32”
(6.38mm±.79)
23/32”
(18.25mm)
7/16”± 1/16”
(11mm±1.6)
FIGURE 36 - Maintain
spark gap of 7/64"
If no spark occurs, check the following:
a) Voltage between Terminals TH and 7 on the ignition controller should be at least
20 volts and no higher than 32 volts. Refer to Troubleshooting (Paragraph 10.3) if
no voltage is observed.
b) Short to ground in the high tension lead and/or ceramic insulator.
c) Pilot spark gap should be approximately 7/64".