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G77x Intermittent Pilot Ignition Controls
The G77x family of controls is designed for indirect ignition of natural
Description
gas, Liquefied Petroleum (LP) gas, manufactured gas, mixed gas, or
LP gas-air mixtures.
Following are the application requirements of the G77x control.
Application
Requirements
• The G77x can be used on gas-fired equipment with a maximum firing
• All G77x applications must use a redundant gas valve system where
© 2000 Johnson Controls, Inc.
Part No. 24-8143-588, Rev. A
Code No. LIT-121250
All manuals and user guides at all-guides.com
Gas Combustion Combination Controls and Systems G
Figure 1: G77x Intermittent Pilot Ignition Controls
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.
the pilot and main valve seats are in series and opened in sequence for
intermittent pilot ignition.
Installation Sheets Manual 121
Technical Bulletin G77x
Issue Date 0600
www.johnsoncontrols.com
1
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Table of Contents
Related Manuals for Johnson Controls G775
Summarization of Contents
Operating Mode Definitions
Prepurge
Initial time delay between thermostat closure and ignition trial.
Trial for Ignition
Pilot valve and spark active, attempting pilot ignition.
Run
Pilot and main gas valves energized after successful ignition.
Shutoff
Pilot fails to ignite; control de-energizes and enters recycle.
Automatic Recycle
Control delays before another trial after shutoff.
Interpurge
Period between trials for gas valve/spark deactivation.
Ignition Lockout
Pilot fails to ignite; requires thermostat reset.
Flameout
Loss of proven pilot flame.
Hard Lockout
Control detects a fault; requires thermostat reset.
Installation and Wiring
Location and Mounting
Guidance on physical placement of the control unit.
Pilot Burner/Igniter-Sensor
Location/Mounting
Guidance on positioning the pilot burner/igniter-sensor assembly.
Service Checkout Procedures
Preliminary Checks
Initial checks before troubleshooting.
Failure Conditions and Corrective Action
Identifying system failures and corrective actions.
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