Johnson Controls G76 Series Installation Sheets Manual
Installation Sheets Manual 121
Gas Combustion Combination Controls and Systems Section G
Technical Bulletin G76x
G76x Direct Spark Ignition Controls
Issue Date 0400
Figure 1: G76x Direct Spark Ignition Controls
Description
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.
Application Requirements
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.
© 2000 Johnson Controls, Inc.
Part No. 24-8143-561, Rev. A www.johnsoncontrols.com
Code No. LIT-121245
1
Table 1: Specifications
Ignition Type
Ignition Source
High Voltage Cable
Maximum Length
Flame Sense Cable
Maximum Length
Flame Detection Means
Flame Detection Types
Minimum Flame
Current
Flame Failure
Response Time
Spark Gap
Ignition Trials
Ignition Trial Times
Prepurge Times
Interpurge
Automatic Recycle
Delay Period
Power Requirements
Contact Rating (MV)
Ambient Operating and
Storage Temperature
Humidity
Wiring Connections
Types of Gas
Packaging
Bulk Pack Quantity
Bulk Pack Weight
Agency Listing
Specification
Standards
*Timings listed are for 60 Hz operations. Timings increase 20% for 50 Hz operation.
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.
Refer to the G76x Series Product Bulletin (LIT-4350420) for necessary information on operating
and performance specifications of this product.
Direct Spark
High voltage spark, capacitive discharge
1,220 mm (48 in.)
1,220 mm (48 in.)
Flame rectification
Remote sensing
0.3 microampere
0.8 second maximum
2.5 mm (0.1 in.) nominal
1 or 3
4, 6, 8, or 10 seconds*
0, 15, or 30 seconds*
30 seconds*
No recycle (G760)
5 minutes* (G765)
60 minutes* (G766)
Control: 24 VAC, 50/60 Hz, nominal
Operation Current: 0.2A nominal + main valve
2A continuous, 5A inrush
-40 to 70°C (-40 to 160°F) standard models
-40 to 80°C (-40 to 175°F) high temperature models
95% RH non-condensing
Spark: Spike, Rajah, or 6.35 mm (1/4 in.) male spade
Control: 6.35 mm (1/4 in.) male spade
4.76 mm (3/16 in.) male spade optional
Natural, Liquefied Petroleum (LP), manufactured, mixed,
or LP gas-air mixture
Bulk pack supplied to original equipment manufacturer
(individual pack optional).
50
15 kg (33 lb)
CSA (AGA/CGA) Certificate Number 164933-1079185
Australian Gas Certificate Number 4524 (G760 models
only)
ANSI Standard Z21.20, Z21.20a, Z21.20b
CAN/CSA-C22.2 No. 199
—G76x Direct Spark Ignition Controls Technical Bulletin
2 G
Operating Mode Definitions
The following definitions describe operating conditions.
• Prepurge--Initial time delay between thermostat contact closure and
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.
• Run--Main gas valve remains energized and spark is turned off after
successful ignition.
• 100% Shutoff--For controls with automatic recycle, main gas did not
ignite within the trial-for-ignition time. The control de-energizes the
spark circuit and main valve.
• Automatic Recycle--If 100% shutoff occurs, the control delays for a
specific recycle delay period before beginning another trial for ignition.
(Models with recycle only.)
• Interpurge--Period between trials for ignition when both the gas valve
and spark are deactivated to allow unburned gas to escape before the
next trial. Interpurge occurs between unsuccessful trials on a multi-trial
control or after a loss of proven flame (flameout).
• Ignition Lockout--Main gas did not ignite within the final
trial-for-ignition time. Open the thermostat contacts for 30 seconds,
then close to restart the sequence of operation. (Models with an
optional Light-Emitting Diode (LED) will flash the LED to indicate
ignition lockout.)
• Flameout--Loss of proven flame.
• Hard Lockout--The control detected a fault. Open the thermostat
contacts for 30 seconds, then close to restart the sequence of operation.
(Models with an optional LED will turn off the LED to indicate a hard
lockout.)
—G76x Direct Spark Ignition Controls Technical Bulletin
G
3
Sequence of Operation
Figure 2 illustrates the sequence of operation of the G76x control.
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. During the trial for ignition, the control attempts to light
the main burner by simultaneously energizing the main gas valve and
supplying a continuous spark at the igniter electrode. If the optional
prepurge is not selected, then the trial for ignition begins within 1 second
after the call for heat. The spark is deactivated immediately following the
trial for ignition.
Under normal conditions, the main burner gas ignites within the
trial-for-ignition period. If the control senses main burner flame by the end
of the trial, the control proceeds to a run condition. During the run state,
the control energizes the main valve until the call for heat ends, or until a
flameout occurs. If main burner flame is not sensed by the end of the
trial-for-ignition period, the control may:
• proceed to a 30-second interpurge followed by another trial (three trial
models whose first two trials produced no flame)
• proceed to lockout (no automatic recycle models whose final trial
produced no flame)
• proceed to a recycle delay period followed by another trial (automatic
recycle models whose final trial produced no flame)
If the main burner flame extinguishes during the run state, the control
de-energizes the main gas valve for an interpurge of 30 seconds. After this
period, another trial for ignition is initiated. If this flameout cycle repeats
for a total of 16 times (main burner flame established, then lost), the
control will:
• Enter the lockout mode if the control is a G760. The thermostat
contacts must be opened for 30 seconds and then closed to escape the
lockout condition.
• Enter the 100% shutoff mode and recycle period (5 minute recycle
delay for the G765 and 60 minute recycle delay for the G766) before
beginning another trial for ignition, starting with prepurge.
—G76x Direct Spark Ignition Controls Technical Bulletin
4 G
Start
Thermostat
call for heat
Prepurge
Flame pr esent when
not expected
No
Flame
present for
30 seconds?
Ye s
Detected Fault
Hard Lockout
(optional LED
turns off)
Interpurge
Main valve
flame sensed?
No
Maximum
number of trials
attempted?
Ignition Lockout
(optional LED
flashes)
No
Ye s
Ye s
No
Control
with ignition
recycle?
Ye s
Recycle delay
period
Ye s
Run
Flameout?
Sixteenth
flameout?
Figure 2: G76x Sequence of Operation
Ye s
No
No
Ye s
Thermostat
calling for heat?
No
De-energize
control and valves
End
—G76x Direct Spark Ignition Controls Technical Bulletin
G
5
Installation and Wiring
IMPORTANT: These instructions are intended as a guide for
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.
!
WARNING: Fire or Explosion Hazard. Avoid serious injury by
carefully following precautions 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.
!
WARNING: Fire or Explosion Hazard. If the control is installed
in an area that is exposed to water (dripping,
spraying, rain, etc.), it must be protected. If the
control has been exposed to water in any way, do not
use it.
Location and
Mounting
!
WARNING: Shock Hazard. Avoid electrical shock and
equipment damage. Disconnect electrical power and
turn off gas before wiring the control into the circuit.
!
CAUTION: Equipment Damage Hazard. Do not mount the
control where it will be exposed to direct infrared
radiation from the main burner or to temperatures in
excess of the maximum product temperature rating.
Choose a location that provides the shortest, direct cable route to the spark
igniter/flame sensor assembly. Easy access to the terminals is desired for
wiring and servicing. The control may be mounted in any position. Mount
the control on a grounded metal surface with metal screws or bolts through
the mounting holes provided in the enclosure.
—G76x Direct Spark Ignition Controls Technical Bulletin
6 G
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