Reznor SCE Unit Installation Manual - Manual (Page 29)

Form RZ-NA I-SCE, Mfg #207697 Rev 7, Page 29
Carryover Lighter Tube
Pilot
Carryover
Regulator
Flash
Carryover
FIGURE 29B - Burner Rack With a Propane Gas
Pilot
Auxiliary
Flame
Probe Propane Gas
Pilot
Pilot
Auxiliary
Sensor
Flash
Carryover
Flash
Carryover
FIGURE 29A - Natural Gas Burner Rack ( does
not apply to furnaces with Option AG39 or AG40)
Natural Gas
Pilot
22. Pilot and
Ignition
Systems
Ignition System
Natural gas units are equipped with a spark ignited intermittent safety pilot system that shuts off
the pilot gas flow between heat cycles. Propane units (or as an option on natural gas units)
require a lockout device that stops the gas flow to the pilot if the pilot fails to light in 120 seconds.
The lockout device requires manual set by interruption of the thermostat circuit. Refer to the
wiring diagram supplied with the unit for pilot system identification and proper wiring. Pilot with
lockout is Option AH3; spark pilot without lockout is Option AH2.
Ignition Controller
As part of the intermittent safety pilot systems, the ignition controller 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 insu-
lated 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 DC as measured by a microampmeter. With pilot flame
proven, the ignition controller energizes the main gas valve.
CAUTION: Due to high voltage on pilot spark wire and pilot electrode, do
not touch when energized. See Hazard Levels, page 2.
Pilot
All pilots are vertical, target type with lint-free feature. Pilot flame should be approximately 1-1/4"
in length. Pilot gas pressure should be the same as the supply line pressure. Pilot gas is supplied
through the combination valve; the pilot gas flow is controlled by an adjustment screw located in
the valve body. For maintenance, see Paragraphs 30 and 31.
23. Burners,
Orifices, and
Carryover
System
Burners
Individually formed steel burners capable of operating on either natural or propane gas are used
in this heater. These burners have accurate, machine-formed ports to give controlled flame stabil-
ity and operation without lifting or flashback. All burners are lightweight and factory mounted in
an assembly which permits all of the burners to be removed as a unit for inspection or service.
Burner Carryover Systems
All natural gas burners (except when equipped with electronic modulation Option AG39 or AG40;
see Paragraph 21) are equipped with two flash carryover systems, one on each end of the burner
rack. (NOTE: A natural gas burner rack on furnaces manufactured prior to Series 6 had a gas
lighter tube carryover and one flash carryover.)
All propane gas burners are equipped with one flash carryover and a regulated gas lighter tube
system. The carryover lighter tube receives its gas supply through a regulator, simultaneously
with the gas to the burner orifices.
During regular service, check the main burner ports, the carryover assemblies, and the orifices for
cleanliness.
Burner Orifices Heaters are shipped with orifices of proper size and type for gas specified. NOTE: Natural gas
units have a dual flash carryover system and do not require a carryover orifice.