Johnson Controls G961DAJ User manual

Installation Sheets Manual 121

Gas Combustion Combination Controls and Systems G

Technical Bulletin G961

Issue Date 0796

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

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

RWC

To second furnace

(if twinned application)

Flame Sensor N/C N/C HN

N/C

TWIN

Optional Blower

Connector

24 VAC

24 COM

LINE NEUTRAL HUM LINE EAC H/C M1

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

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