Johnson Controls G961DAJ User manual

Installation Sheets Manual 121
Gas Combustion Combination Controls and Systems G
Technical Bulletin G961
Issue Date 0796
© 1996 Johnson Controls, Inc. 1
Part No. 24-8143-502
Code No. LIT-121885
The G961DAJ is a microprocessor-based, direct spark, remote flame
sense, integrated function ignition control designed specifically for a
Rheem furnace application. The G961DAJ responds to inputs from the
thermostat, limit switch(es), pressure switch, flame sensor, and power
supply. The G961DAJ provides outputs for timing and sequencing of the
main gas valve, induced draft motor, indoor blower motor, electronic air
cleaner, humidifier, and spark igniter.
All G961DAJ applications must use redundant gas valves. Any
application over 400,000 Btu/hr must be approved in advance by Johnson
Controls Application Engineering.
G961DAJ Integrated Function Ignition Control
Application

2 G Gas Combustion Combination Controls and Systems—G961DAJ Integrated Function Ignition Control
Table 1: Specifications
Specification Rating
Line Voltage 120 VAC, 50/60 Hz, nominal
Secondary Voltage 24 VAC, 50/60 Hz, nominal
Operating Current 0.4A nominal + main valve
Contact Ratings
Valve
Inducer
Blower
Humidifier
Electronic Air Cleaner
1A max., 3A inrush @ 24 VAC
2.5 max. FLA, 2.5 max. LRA @ 120 VAC
10.5 max. FLA, 26 max. LRA @ 120 VAC
1A max. @ 120 VAC
1A max. @ 120 VAC
Flame Sensing Current
Flame Threshold Current (ITH)
Insufficient Flame
Marginal Flame
Good Flame
0.3 microamperes +/- 25%
Flame Current < ITH
ITH < Flame Current < 4 x ITH
Flame Current > 4 x ITH
Prepurge Time 30 seconds*
Trial for Ignition Time 8 seconds*
Interpurge Time 30 seconds*
Flame Failure Response Time 0.8 seconds
Postpurge Time 5 seconds*
Number of Trials Allowed Before Soft
Lockout 4
Number of Flameouts Allowed Before Soft
Lockout 5
Automatic Reset Delay Time 60 minutes*
Operating and Storage Temperature -40 to 160°F (-40 to 71°C)
Humidity 95% RH non-condensing
Types of Gas Natural, Liquefied Petroleum (LP),
manufactured, mixed, LP gas-air mixture
Agency Approvals IAS (AGA, CGA)
Agency Test Standards ANSI Z21.20, CAN/CSA-C22.2 No. 199
* Timings based on 60 Hz operation. Timings increase 20% for 50 Hz operation.

G—Gas Combustion Combination Controls and Systems—G961DAJ Integrated Function Ignition Control 3
The normal system operation for the G961DAJ depends on the demand
from the system thermostat.
Upon receiving a call for heat from the system thermostat, the G961DAJ
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 for the entire
prepurge period.
3. Pressure Switch Detection--The control checks the pressure switch to
ensure that is has closed.
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 gas valve is energized for the entire 8 seconds, the
spark igniter is energized for the first 7 seconds, and the control
attempts to sense main burner flame during the last 1 second.
5. Run--If main burner flame is sensed within the last 1 second of the
trial, the gas valve remains energized, and the heat fan-on delay
begins. Once the heat fan-on delay expires, the blower motor is
energized at heating speed.
6. Postpurge--Once the thermostat is satisfied, the gas valve is
de-energized, the inducer motor remains energized until the postpurge
period ends, and the heat fan-off delay begins. Once the heat fan off
delay expires, the blower motor is de-energized.
Upon receiving a call for cool from the system thermostat, the G961DAJ
energizes the blower motor at cooling speed. Once the thermostat is
satisfied, the control waits for the cool fan-off delay to expire before
de-energizing the blower motor.
Upon receiving a call for continuous fan-on, the G961DAJ energizes the
indoor blower motor at fan-on speed. The continuous fan-on request is
immediately overridden by a heat or cool demand.
Upon receiving a call for heat and cool simultaneously, the G961DAJ
initiates a normal heating cycle; however, the indoor blower motor
remains energized at cooling speed. The system immediately returns to
normal cooling operation when the auxiliary heat demand is satisfied.
Upon receiving a call for heat at the same time an existing demand for
cooling is interrupted, the G961DAJ initiates a normal heating cycle;
however, the cool fan off delay is preempted.
Normal
Sequence of
Operation
Call for Heat
Call for Cool
Call for Fan-On
Call for Auxiliary
Heat
Call for
Emergency Heat

4 G Gas Combustion Combination Controls and Systems—G961DAJ Integrated Function Ignition Control
The G961DAJ 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 G961DAJ control responds to the state
of this switch in the following ways:
1. If the pressure switch is not open at the beginning of the heating
cycle, the control will wait for the switch to open.
2. If the pressure switch does not close after the inducer motor has been
energized for 60 seconds, the inducer motor will be de-energized for
300 seconds, and then re-energized. This cycle will continue until the
pressure switch is proven closed, as long as the demand for heat
exists.
3. If the pressure switch opens during the trial for ignition (before flame
is sensed), all outputs will be de-energized and the control will begin
another heating sequence beginning with Pressure Switch Detection.
4. If the pressure switch opens during the run state (after flame is
sensed), the main valve will be de-energized, and the inducer and
blower will run for a 180 second purge. Once this purge period
expires, the control will begin another heating sequence beginning
with Pressure Switch Detection.
Note: If the pressure switch re-closes and remains closed within
12 power line cycles (forgiveness period), the operating cycle will
continue uninterrupted.
Any time flame is sensed while the gas valve is de-energized, the inducer
and blower motors will be energized. When flame is no longer sensed, the
inducer will be de-energized, and the blower will continue to run through a
30 second fan-off delay. Once expired, the control will respond to the
thermostat call.
If the first ignition attempt and the first retry both fail to establish flame,
the control will activate a self-healing over-temperature correction cycle
before the next retry. This is accomplished by running the inducer and
blower for 180 seconds, before proceeding to the third trial (second retry).
If flame is not sensed by the end of the trial for ignition period, the gas
valve is de-energized, the inducer runs through an interpurge period, and
another trial for ignition begins. If flame is not sensed before the end of
the fourth trial, the control proceeds to a 60 minute soft lockout period
(during which all outputs are de-energized) before resetting itself.
Abnormal
System
Operation
Pressure Switch
Detection
Undesired Flame
Self Healing
Function
Failure to Sense
Flame Within
Trial Period

G—Gas Combustion Combination Controls and Systems—G961DAJ Integrated Function Ignition Control 5
If the main burner flame is established and then lost, the gas valve is
de-energized and the inducer runs through an interpurge. Once the
interpurge period expires, the control initiates another trial for ignition.
The blower will be energized and/or remain energized for the duration of
the interpurge and the ignition retry. After the fifth flameout, the control
proceeds to a 60 minute soft lockout period (during which all outputs are
de-energized) before resetting itself.
Certain models of furnace include an auxiliary limit switch in-line with the
gas valve. The switch responds to an overtemperature condition in the
blower compartment. If the limit switch opens, the power to the gas valve
will be interrupted, causing the control to react to a flameout.
The G961DAJ offers the following responses to the three possible
interrupted thermostat situations.
1. If the call for heat is removed before the gas valve is energized, the
G961DAJ will de-energize all outputs and reset.
2. If the call for heat is removed after the gas valve is energized, but
before flame has been sensed, the gas valve and spark igniter are
de-energized, and the inducer motor will run through a postpurge.
3. If the call for heat is removed after flame has been sensed, but before
the blower comes on, the gas valve is de-energized, the inducer will
run through a 5 second purge, and the blower will run through a
180 second blower-off delay.
The high limit switch is monitored constantly. Any time the switch opens,
the gas valve and igniter will be de-energized, and the inducer and blower
(heat speed) will run continuously. When the switch is reset, the inducer
and the blower will run for 180 seconds before the control returns to
normal operation.
The twinning function allows for simultaneous safe operation of
two furnaces equipped with the same furnace controls (e.g., G961DAJ).
The two controls are connected and operate simultaneously from a single
thermostat. The twinning connection forces the blowers of each furnace to
operate synchronously into a common duct system.
Upon receiving a call for heat (or cool), the controls simultaneously
perform the normal operating sequences detailed previously.
Flameout
Overtemperature
Condition
Interrupted
Thermostat
High Limit Switch
Twinning
Operation
Normal Operation

6 G Gas Combustion Combination Controls and Systems—G961DAJ Integrated Function Ignition Control
The controls are connected to a two stage thermostat. When the first stage
calls for heat (or cool), the blower motors are simultaneously energized,
but the ignition sequence (or cooling sequence) only takes place in the first
furnace. When the second stage calls for heat (or cool), the ignition
sequence (or cooling sequence) starts in the second furnace without
interrupting the operation of the blowers.
In any of the safety functions, soft lockout, or abnormal operation modes,
if only one furnace is affected, the other furnace will continue its normal
operating cycle and maintain control of the affected furnace’s blower.
The affected furnace will initiate its abnormal operating sequence, with
the exception of interrupting blower operation.
If the abnormal condition still exists after the demand for heat (or cool) is
satisfied, the safety function or abnormal operation sequence will take
over the operation of both blowers.
Twinning communications can be lost due to:
1. Lack of continuity between “TWIN” terminals and/or between the
common terminals of the two furnaces.
2. Loss of power in one of the twinned furnaces.
3. The 24 VAC signal on the two controls out of phase.
A loss of communications will result in the two controls de-energizing all
outputs except the inducer, which runs for 4 seconds and the blower,
which runs for 180 seconds. The “OK” LED will flash to indicate loss of
communication between furnaces while in twinning mode. Once the
purge period expires, the controls attempt to restore communications
before returning to normal operation.
!
WARNING: Shock Hazard. Disconnect power supply before
wiring to prevent electrical shock or equipment
damage.
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.
This instruction sheet is intended as a guide for qualified personnel installing
or servicing Johnson Controls ignition controls. Carefully follow all
instructions on this sheet and all instructions on the appliance. Limit repairs,
adjustments, and servicing to the operations listed in this sheet or on the
appliance.
Two Stage
Operation
Abnormal
Operation
Loss of
Communications
Installation and
Wiring

G—Gas Combustion Combination Controls and Systems—G961DAJ Integrated Function Ignition Control 7
Check the voltage rating marked on the control or in Table 1 to be sure it
is suited to the application. Use an NEC Class 2 transformer, such as a
Johnson Controls Y65, to provide 24 VAC under maximum load,
including the valve.
Choose a location with the shortest direct cable route to the spark igniter
and flame sensor. To wire the G961DAJ, follow the schematic in
Figure 1. All wiring should be in accordance with the National Electrical
Code (NEC) and all other local codes and regulations. The high voltage
spark cable must not be in continuous contact with a metal surface. Use
standoff insulators. Be certain the flame sensor wire and the high voltage
spark cable are separated from one another by a minimum of 1/4 inch, and
not wrapped around any pipe, other wiring, or accessories.

8 G Gas Combustion Combination Controls and Systems—G961DAJ Integrated Function Ignition Control
Inducer
Electronic
Air Cleaner
Humidifier
Blower
120 VAC
Hot (H)
Neutral (N)
Transformer
24 VAC
Secondary 120 VAC
Primary
Main
Valve
Main
Valve
Spark
Electrode
Thermostat
High
Limit
Switch
Pressure
Switch
Y
G
RWC
To second furnace
(if twinned application)
Flame Sensor N/C N/C HN
H
N
N/C
HN
HN
H
N
TWIN
Optional Blower Connector
24 VAC
24 COM
LINE NEUTRAL HUM LINE EAC H/C M1
M2
g961daj.drw
Figure 1: Wiring Diagram for G961

G—Gas Combustion Combination Controls and Systems—G961DAJ Integrated Function Ignition Control 9
!
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 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. Do a leak check on all pipe joints downstream of the gas valve.
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.
If the system does not function properly, determine the cause using the
procedures in this section.
Before proceeding with troubleshooting the system, check the following:
Are all mechanical and electrical connections tight?
Is system wired correctly?
Is gas inlet pressure per manufacturer’s specifications?
Is system powered?
Is thermostat calling for heat?
Checkout and
Startup
Procedures
Service
Procedures
Preliminary
Checks

10 G Gas Combustion Combination Controls and Systems—G961DAJ Integrated Function Ignition Control
The G961DAJ control features three diagnostic LEDs. The LEDs indicate
the following system status:
•Green “PWR” LED--On indicates the control has 24 VAC. Off
indicates control does not have 24 VAC.
•Green “OK” LED--On indicates normal operation. Off indicates
internal or external fault. Flashing indicates loss of twinning
communications.
•Yellow “FLAME” LED--On indicates good flame sense current. Off
indicates insufficient flame sense current. Flashing indicates marginal
flame sense current.
Refer to the appliance manufacturer’s recommended troubleshooting
guidelines. If unavailable, determine the failure condition and use the
following service tips to troubleshoot the system.
Table 2: No Power to System (Green “PWR” LED Off)
Possible Causes Corrective Actions
Tripped circuit breaker Reset circuit breaker.
Faulty transformer Replace transformer.
Faulty wiring Repair or replace wiring.
Table 3: Internal Fault (Green “OK” LED On)
Possible Causes Corrective Actions
Noise problems Isolate system electrically from noise source.
Defective ignition control Replace ignition control.
Table 4: External Fault (Green “OK” LED On)
Possible Causes Corrective Actions
Maximum number of retries exceeded
due to failure to ignite gas during trial Check/correct gas pressure and position of
spark igniter.
Maximum number of retries exceeded
due to low flame sense current Refer to Table 6 or 7.
Maximum number of flameouts exceeded Check/correct gas pressure, drafts, low
flame sense current.
Flame sensed when gas valve is
de-energized Check for leaking or slow closing gas valve
and replace where necessary.
Flash Codes
Failure
Conditions and
Corrective Action