Johnson Controls G861 Series Service manual

Installation Sheets Manual 121
Gas Combustion Combination Controls and Systems Section G
Technical Bulletin G861
Issue Date 0699
© 1999 Johnson Controls, Inc. 1
Part No. 24-8143-553, Rev. A www.johnsoncontrols.com
Code No. LIT-121920
Figure 1: G861 Integrated Function
Direct Spark Ignition Control
The G861 is a microprocessor-based, 100% shutoff, direct spark, and
remote flame sense, integrated function ignition control. The G861
responds to inputs from the thermostat, high limit switch, pressure switch,
and flame sensor. It provides outputs for timing and sequencing of the main
gas valve, induced draft motor, circulator/blower, and spark igniter.
The G861 utilizes quick-connect terminals for all off board connections,
except thermostat inputs and spark output. The thermostat inputs are
connected to a terminal strip with screw terminals and the spark output is
connected by a rajah, spike, or 1/4 in. male tab-type spark connector.
All G861 applications must use redundant gas valves and the pressure
switch must carry main valve current. Any application over
117 kW (400,000 Btu/hr) must be approved in advance by
Johnson Controls Application Engineering.
G861 Series Integrated Function
Direct Spark Ignition Control
Application

2 G—G861 Series Integrated Function Direct Spark Ignition Control Technical Bulletin
Table 1: Specifications
Ignition Type Direct
Ignition Source High voltage spark, capacitive discharge
High Voltage Cable Length 1,220 mm ( 48 in.) maximum
Flame Detection Means Flame rectification
Flame Detection Types Remote sensing
Minimum Flame Current
Flame Threshold Current (ITH)
Insufficient Flame
Marginal Flame
Good Flame
0.250 microampere ±25%
Flame current <ITH
ITH < flame current <4 x ITH
Flame current >4 x ITH
Flame Failure Response Time 0.8 second @ 0.500 microampere flame current
Spark Gap 3.17 mm (0.125 in.) nominal
Ignition Trials 3
Ignition Trial Time 7, 8, 10, or 11 seconds*
Prepurge Time 0, 10, or 30 seconds*
Postpurge 15, 30, or 45 seconds*
Interpurge 10 seconds*
Automatic Retry Delay Period 60 minutes*
Flameout Recycles 16 including the initial ignition trial
Circulator/Blower “On Delay” 30 seconds*
Circulator/Blower “Off Delay” 90, 120, 180, or 240 seconds*
Power Requirements Line Voltage 120 VAC, 50/60 Hz
Control: 24 VAC, 50/60 Hz, nominal
Operation Current: 0.3A @ 24 VAC
Contact Rating Main Valve: 2A continuous at 24 VAC, 5A inrush
Inducer: 2A continuous, 120 VAC
Blower: 1/3 hp (7.20 FLA), 125 VAC
Ambient Operating and Storage
Temperature -40 to 70°C (-40 to 160°F)
Humidity 95% RH non-condensing
Wiring Connections Spark: Spike, rajah, or 1/4 in. male tab
Types of Gas Natural, Liquefied Petroleum (LP), manufactured, mixed,
or LP gas-air mixture
Packaging Bulk pack supplied to original equipment manufacturer
(individual pack optional).
Bulk Pack Quantity 24
Bulk Pack Weight 8 kg (18 lb)
Agency Listing CSA (AGA/CGA) Certificate Number 11250-7
Specification Standards ANSI Standard Z21.20
CSA C22.2-No. 199
*Timings listed are for 60 Hz operations. Timings increase by 20% under 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 G861 Product Bulletin (LIT-4350440) for necessary information on operating and
performance specifications of this product.

G—G861 Series Integrated Function Direct Spark Ignition Control Technical Bulletin 3
The following conditions occur in normal control operation:
•Prepurge--Initial time delay between thermostat contact closure and
trial for ignition.
•Trial-for-Ignition Time--Maximum time period that the main gas valve
and igniter energizes in an attempt to light the main burner.
•Interpurge--Time period between trials for ignition when both the gas
valve and ignition source turn off and the inducer is on, allowing
unburned gas to escape before a succeeding trial can occur. (Retry takes
place only if proper ignition did not occur during the previous trial and
if total trials are less than three.)
•Run--Main gas valve remains energized after a successful ignition trial.
•Circulator/Blower “On Delay”--Fixed time delay after the flame is
sensed until the circulator/blower is energized.
•Circulator/Blower “Off Delay”--Field selectable time delay after the
thermostat contacts open when the circulator/blower remains energized.
•Postpurge--Time delay after the thermostat is satisfied when the
inducer remains energized.
Figure 2 illustrates the sequence of operation of the G861 control.
Upon receiving a call for heat from the system thermostat, the G861
follows this normal sequence of operation:
1. Pressure Switch Detection--The control checks the inducer pressure
switch to ensure that it is open.
2. Prepurge--The control energizes the inducer motor and verifies that the
pressure switch closes.
3. Pressure Switch Detection--The control checks the pressure switch to
ensure that it remains closed during the prepurge period.
4. Trial for Ignition--The control simultaneously energizes the spark
igniter and gas valve in an attempt to light the main burner. During the
trial time, the igniter is energized until flame is detected or until the
trial for ignition is complete, whichever occurs first.
5. Run--If main burner flame is sensed up to the last 0.5 second of the
trial, the gas valve and inducer remain energized for the duration of the
heat call. The circulator/blower is energized after a 30-second blower
“on delay” time and remains energized for the duration of the heat call.
6. Postpurge--Once the thermostat is satisfied, the gas valve is
de-energized and the inducer remains energized until the postpurge
period ends. The circulator/blower remains energized until the selected
blower “off delay” time has elapsed.
Operating
Mode
Definitions
Normal
Sequence of
Operation
Call for Heat

4 G—G861 Series Integrated Function Direct Spark Ignition Control Technical Bulletin
Start
Inducer on
Inducer off
Prepurge
Run
Interpurge
Yes
No
Yes
No
Yes
Yes
Flameout? Yes
No
No
Postpurge
No
End
Thermostat calls
for manual fan (G)
No
Run - manual
fan speed
Thermostat
call for heat
Pressure
switch open?
Yes
Retry mode
60 minute delay
No
Yes
Pressure
switch closed?
Third
trial?
Trial for
ignition Sixteenth
flameout?
Flame
sensed?
Circulator/Blower
“on delay”
Thermostat
satisfied?
Circulator/Blower
“off delay”
(field selectable)
Figure 2: G861 Sequence of Operation

G—G861 Series Integrated Function Direct Spark Ignition Control Technical Bulletin 5
Upon receiving a call for continuous manual fan, the G861 energizes the
circulator/blower motor at medium fan speed. The continuous fan on
request is immediately overridden by a call for heat.
The G861 offers the following responses based on abnormal system
operation.
A pressure switch within the appliance provides proof of combustion air
flow. During a heating cycle, the G861 control responds to the state of this
switch in the following ways:
•At the beginning of the heating cycle, if the pressure switch is not open
before the inducer is energized, the control will wait for the switch to
open for as long as the call for heat is present. The G861 control LED
(Light-Emitting Diode) will blink with a flash code of 3 while waiting
for the pressure switch to open.
•If the pressure switch does not close after the inducer has been
energized for 8 seconds, the control will keep the inducer energized and
the LED will blink with a flash code of 3 until the pressure switch
closes or the call for heat is removed.
•If the pressure switch opens any time after the G861 control has begun
the trial for ignition, the control will immediately de-energize the gas
valve. If the pressure switch fault occurs after the flame is sensed, the
circulator/blower will run for 90 seconds, the inducer motor will remain
energized, and the control will go into the Pressure Switch Open Fault
state. During this time, the LED will blink with a flash code of 3. As
long as the call for heat is still present, the control will continue to wait
for the pressure switch to close before resuming the heating cycle. If the
pressure switch fails three times with no more than 30 seconds between
successive faults, the control will go to PSWFLT1 and PSWFLT 2 state
with an LED flash code of 3.
If a flame is present at power up, the G861 allows the flame to extinguish
within 10 seconds. If this occurs, the normal sequence of operation
continues. If the flame is still present after 10 seconds, the G861 goes into
flame lockout. If flame is present any other time it should not be, the G861
goes into flame lockout after a 10-second delay.
During the flame lockout, the inducer motor and the circulator/blower
remain energized, and the main valve is de-energized. The G861 control
LED flashes with a duty cycle of 1/2 second On, 1/2 second Off for
five flashes with a longer Off time before repeating the series. The control
remains in this state until the main power is cycled.
Call for Manual
Fan
Abnormal
System
Operation
Pressure Switch
Detection
Undesired Flame

6 G—G861 Series Integrated Function Direct Spark Ignition Control Technical Bulletin
If a flame is not sensed by the end of the trial-for-ignition period, the gas
valve is de-energized, the inducer remains energized through the 10-second
interpurge period, and another trial for ignition begins. If a flame is not
sensed before the end of the third trial, the control proceeds to a 60-minute
retry delay period, where all outputs are de-energized, before resetting
itself. During the 60-minute retry delay period, the LED will blink with a
flash code of 2.
A “manual fan” call from the thermostat during the 60-minute retry will run
the circulator/blower at medium speed.
If the main burner flame is established and then lost, the gas valve is
de-energized and the inducer and circulator/blower run through a
10-second interpurge. Once the interpurge period expires, the control
initiates another trial for ignition.
After the sixteenth flameout in any given heating cycle, the control
proceeds to a 60-minute retry delay peroid, where all outputs are
de-energized. A “manual fan” call from the thermostat will run the
circulator/blower at medium speed. During the 60-minute retry delay
period, the LED will blink with a flash code of 2.
A “manual fan” call from the thermostat during the 60-minute retry will run
the circulator/blower at medium speed.
The G861 offers the following responses to the two possible interrupted
thermostat situations:
•If the call for heat is removed before the gas valve is energized, the
G861 will de-energize all outputs and return to the Off state.
•If the call for heat is removed any time after the gas valve is energized,
the gas valve and spark igniter (if energized) are de-energized, the
inducer motor will run through the postpurge period, and the
circulator/blower will run for the selected blower “off delay” time.
The high limit switch is monitored whenever a call for heat is present. Any
time the switch opens, the gas valve and igniter are de-energized, and the
inducer and circulator/blower run continuously. When the switch is reset,
the inducer and circulator/blower run for 180 seconds before the control
returns to normal operation. Whenever the high limit switch is open while
the call for heat is present, the control LED will blink with a flash code of 4.
Failure to Sense
Flame Within
Trial Period
Flameout
Interrupted
Thermostat
High Limit
Switch

G—G861 Series Integrated Function Direct Spark Ignition Control Technical Bulletin 7
IMPORTANT: This technical bulletin is intended as a guide for
qualified personnel installing or servicing
Johnson Controls products. Carefully follow all
instructions in this sheet and all instruction on the
appliance. Limit repairs, adjustments, and servicing
to the operations listed in this sheet or on the
appliance.
!
WARNING: Fire or Explosion Hazard. Avoid serious injury by
carefully following precautions in this sheet and all
instructions on the appliance. Limit repairs,
adjustments, and servicing to the operations listed in
this sheet 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.
!
WARNING: Shock Hazard. Avoid electrical shock and
equipment damage. Disconnect the electrical
power and turn off the gas before wiring the
control into the circuit.
Choose a location that provides the shortest, direct cable route to the spark
igniter and flame sensor. Easy access to the terminals is desired for wiring
and servicing. The G861 may be mounted in any position. Mount the
control on a grounded metal surface with No. 8 machine or No. 6 sheet
metal screws.
!
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.
Installation and
Wiring
Mounting

8 G—G861 Series Integrated Function Direct Spark Ignition Control Technical Bulletin
!
CAUTION: Equipment Damage Hazard. Connect the high
voltage cable to the spark transformer terminal and
spark igniter before applying power to the control.
Check the voltage rating marked on the control and ensure it is suited to the
application. Use an NEC Class 2 transformer to provide 24 VAC under
maximum load, including the valve. A transformer having excessive
primary impedance due to poor coupling will affect the ignition potential.
Refer to Figure 3 for the G861 wiring diagram. All wiring should be in
accordance with the National Electrical Code (NEC) and all other local
codes and regulations. The high voltage spark transformer cable must not
be in continuous contact with a metal surface. Use standoff insulators.
Ensure that the flame sensor wire and high voltage spark transformer cable
are separated from one another by a minimum distance of 6.35 mm (1/4 in.)
and are not wrapped around any pipe, other wiring, or accessories.
Electrical
Connections

G—G861 Series Integrated Function Direct Spark Ignition Control Technical Bulletin 9
Valve
ACBHeat
CMBBlower
Line
VACHot
Circulator/Blower
Motor
Inducer
Motor
Redundant
MainValve
Coils
3/16inch
Terminal
L1
L2
Line
Neutral
120VAC
Line
Transformer24VLine
24VCommon
Spark
Transformer
24VACHot
Ground
FlameSense
PSW
PressureSwitch
HighLimitIn
HighLimitOut
RolloutIn
Blower
“OffDelay”
Setting
HighLimitSwitch
RolloutSwitch
Thermostat
3/16inch
Terminal
WG
R
Sensor
Note:Allterminalsare1/4inchunlessotherwisespecified.
Pressureswitchmustcarrymainvalvecurrentforredundancy.
Figure 3: G861 Terminal Interface Wiring Diagram

10 G—G861 Series Integrated Function Direct Spark Ignition Control Technical Bulletin
!
WARNING: Fire or Explosion Hazard. Avoid personal injury
or property damage by making sure the control
functions properly and there are no gas leaks.
Follow this checkout and startup procedure before
leaving the installation.
Make sure all components function properly by performing the following
shutoff test:
1. With the gas and thermostat off, turn on power to the appliance.
2. Turn the thermostat to a high setting and verify that the control goes
through the operating sequence to a shutoff condition.
Note: The burner will not light because the gas is off.
3. Turn the thermostat off.
4. Turn gas on and purge gas lines of all air.
5. Check for gas leaks on all pipe joints upstream of the gas valve with a
soap solution.
6. Turn the thermostat to a high setting and verify successful ignition and
a normal run condition for at least three minutes.
7. Check for gas leaks on all pipe joints downstream of the gas valve with
a soap solution.
8. Turn the thermostat down for at least 30 seconds, and then back up
again. Verify successful ignition at least three times before leaving the
installation.
Checkout and
Startup
Procedures