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G76x Direct Spark Ignition Controls
Description
Application
Requirements
© 2000 Johnson Controls, Inc.
Part No. 24-8143-561, Rev. A
Code No. LIT-121245
Gas Combustion Combination Controls and Systems Section G
Figure 1: G76x Direct Spark Ignition Controls
The G76x family of controls is designed for direct main burner ignition
and supervision. The G76x is approved for ignition of natural gas,
Liquefied Petroleum (LP) gas, manufactured gas, mixed, or LP gas-air
mixtures.
Following are the application requirements of the G76x control.
• The G76x can be used on gas-fired equipment with a maximum firing
rate of 117 kW (400,000 Btu/hr). Any application over 117 kW
(400,000 Btu/hr) must have written approval in advance from the
Johnson Controls Heating Products Engineering Department.
• All G76x applications must use a redundant gas valve system where
the main valve seats are in series and open simultaneous for direct
spark burner ignition.
Installation Sheets Manual 121
Technical Bulletin G76x
Issue Date 0400
www.johnsoncontrols.com
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Related Manuals for Johnson Controls G76 Series
Summary of Contents for Johnson Controls G76 Series
- Page 1 117 kW (400,000 Btu/hr). Any application over 117 kW (400,000 Btu/hr) must have written approval in advance from the Johnson Controls Heating Products Engineering Department. • All G76x applications must use a redundant gas valve system where the main valve seats are in series and open simultaneous for direct spark burner ignition.
- Page 2 The performance specifications are nominal and conform to acceptable industry standards. For application at conditions beyond these specifications, consult the local Johnson Controls office. Johnson Controls, Inc. shall not be liable for damages resulting from misapplication or misuse of its products.
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Page 3: Operating Mode Definitions
The following definitions describe operating conditions. Operating Mode • Prepurge--Initial time delay between thermostat contact closure and Definitions trial for ignition. • Trial for Ignition--Period during which the main gas valve and spark are energized in an attempt to ignite gas at the main burner. The control attempts to prove flame at the main burner within the trial-for-ignition time. -
Page 4: Sequence Of Operation
Figure 2 illustrates the sequence of operation of the G76x control. Sequence of Operation The G76x is energized on a call for heat from the system thermostat. (Models with an optional LED will turn on the LED [steady on] until the call for heat is satisfied.) If the control is equipped with the optional prepurge, the control will delay for the time selected before initiating a trial for ignition. - Page 5 Start Flame present when not expected Detected Fault Thermostat call for heat Flame Hard Lockout present for (optional LED 30 seconds? turns off) Prepurge Main valve flame sensed? Thermostat Flameout? calling for heat? Maximum number of trials Interpurge attempted? Control Ignition Lockout De-energize Sixteenth...
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Page 6: Installation And Wiring
These instructions are intended as a guide for Wiring qualified personnel installing or servicing Johnson Controls ignition controls. Carefully follow all instructions in this bulletin and all instructions on the appliance. Limit repairs, adjustments, and servicing to the operations listed in this bulletin or on the appliance. - Page 7 Electrical CAUTION: Equipment Damage Hazard. Connect the high Connections voltage cable to the spark transformer terminal and spark electrode before applying power to the control. Ensure that the ground wire is attached to the sensor assembly and the ignition control ground terminal strip.
- Page 8 Spark Electrode Instructions for installing the spark electrode and sensor assembly are and Sensor typically provided by the appliance manufacturer. It is important to follow Assembly those instructions. If such information is not included, use the following basic instructions. Location/Mounting The spark electrode and sensor assembly must be positioned for easy access and securely mounted to the main burner to ensure that the assembly remains properly positioned with respect to the main burner...
- Page 9 Checkout and WARNING: Fire or Explosion Hazard. Avoid personal injury Startup or property damage by making sure the control Procedure functions properly and there are no gas leaks. Follow this checkout and startup procedure before leaving the installation. WARNING: Fire or Explosion Hazard. Do not attempt to check out this system by manually lighting the main burner.
- Page 10 The anticipator setting is normally equal to the ignition system current Thermostat draw, plus that of the main valve. Heat Anticipator Due to variations in appliance wiring and valves, it is advisable to measure Settings the actual current draw of the heating system at the thermostat location. Measuring the current draw can be accomplished by opening the thermostat contacts (lowering the setpoint), and installing an AC ammeter across the terminals, or by using a clamp-on ammeter with a 10-turn...
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Page 11: Replacement Procedure
Replacement WARNING: Shock Hazard. Avoid electrical shock and Procedure equipment damage. Disconnect electrical power and turn off gas before wiring the control into the circuit. CAUTION: Equipment Damage Hazard. Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper and dangerous operation. Verify proper operation after servicing. - Page 12 Modifying All spark ignition controls have a spark transformer connected to a high Existing Ignition voltage cable. There are three types of connection for the high voltage Cable cable: Spike, Rajah, and 6.35 mm (1/4 in.) male spade (see Figure 5). The replacement G76x has a Spike transformer.
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Page 13: Preliminary Checks
Service WARNING: Fire or Explosion Hazard. Do not attempt Checkout servicing or troubleshooting when the LED is Procedures flashing (recycle mode). The control automatically energizes the system and could cause personal injury or property damage. If the system does not function properly, determine the cause using the procedures in this section. - Page 14 Is 24 VAC Is jumper Is 24 VAC present from installed from available at Start Terminal THS 2 Terminal 5 to transformer? to ground? ground? Install Is power Are thermostat Determine why jumper available contacts and limit voltage is not to primary? control contacts present...
- Page 15 main valve wiring Start Correct correct and secure? Is 24 VAC present between Replace Terminal 3 and control ground? Does Replace continuity exist in wiring wiring to main valve? Is inlet gas pressure per manufacturer’s Correct specifications? Is spark gap Correct or per manufacturer’s replace electrode...
- Page 16 flame sensor Start wiring correct and Correct secure? Does continuity Replace exist in wiring wiring to flame sensor? Is flame sensor Replace ceramic cracked or sensor broken? Clean sensor Is flame with steel wool sensor or replace clean? Does continuity Add or exist between burner replace...
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Page 17: Repairs And Replacement
Use only an exact or factory-recommended replacement control. All other accessories, such as flame sensors, electrode assemblies, pilot assemblies, and leads can be obtained through the original equipment manufacturer or a Johnson Controls distributor. G—G76x Direct Spark Ignition Controls Technical Bulletin... - Page 18 Notes G—G76x Direct Spark Ignition Controls Technical Bulletin...
- Page 19 Notes G—G76x Direct Spark Ignition Controls Technical Bulletin...
- Page 20 Notes Controls Group www.johnsoncontrols.com 507 E. Michigan Street FAN 121 P.O. Box 423 Installation Sheets Manual Milwaukee, WI 53201 Printed in U.S.A. G—G76x Direct Spark Ignition Controls Technical Bulletin...