Johnson Controls G76 Series User manual

Installation Sheets Manual 121

Gas Combustion Combination Controls and Systems Section G

Technical Bulletin G76x

Issue Date 0400

Part No. 24-8143-561, Rev. A www.johnsoncontrols.com

Code No. LIT-121245

Figure 1: G76x Direct Spark Ignition Controls

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.

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.

G76x Direct Spark Ignition Controls

Description

Application

Requirements

2 G—G76x Direct Spark Ignition Controls Technical Bulletin

Table 1: Specifications

Ignition Type Direct Spark

Ignition Source High voltage spark, capacitive discharge

High Voltage Cable

Maximum Length

1,220 mm (48 in.)

Flame Sense Cable

Maximum Length

1,220 mm (48 in.)

Flame Detection Means Flame rectification

Flame Detection Types Remote sensing

Minimum Flame

Current

0.3 microampere

Flame Failure

Response Time

0.8 second maximum

Spark Gap 2.5 mm (0.1 in.) nominal

Ignition Trials 1 or 3

Ignition Trial Times 4, 6, 8, or 10 seconds*

Prepurge Times 0, 15, or 30 seconds*

Interpurge 30 seconds*

Automatic Recycle

Delay Period

No recycle (G760)

5 minutes* (G765)

60 minutes* (G766)

Power Requirements Control: 24 VAC, 50/60 Hz, nominal

Operation Current: 0.2A nominal + main valve

Contact Rating (MV) 2A continuous, 5A inrush

Ambient Operating and

Storage Temperature

-40 to 70°C (-40 to 160°F) standard models

-40 to 80°C (-40 to 175°F) high temperature models

Humidity 95% RH non-condensing

Wiring Connections 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

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 50

Bulk Pack Weight 15 kg (33 lb)

Agency Listing CSA (AGA/CGA) Certificate Number 164933-1079185

Australian Gas Certificate Number 4524 (G760 models

only)

Specification

Standards

ANSI Standard Z21.20, Z21.20a, Z21.20b

CAN/CSA-C22.2 No. 199

*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.

G—G76x Direct Spark Ignition Controls Technical Bulletin 3

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.)

Operating

Mode

Definitions

4 G—G76x Direct Spark Ignition Controls Technical Bulletin

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.

Sequence of

Operation

G—G76x Direct Spark Ignition Controls Technical Bulletin 5

No Yes

Yes

No Maximum

number of trials

attempted?

Yes

Yes No

Yes

De-energize

control and valves

Flame

present for

30 seconds?

Thermostat

call for heat

Hard Lockout

(optional LED

turns off)

Run

Thermostat

calling for heat?

Sixteenth

flameout?

Ignition Lockout

(optional LED

flashes)

Interpurge

Flameout?

End

Start

Flame present when

not expected

Main valve

flame sensed?

Prepurge

Control

with ignition

recycle?

Recycle delay

period

Yes

Detected Fault

Figure 2: G76x Sequence of Operation

6 G—G76x Direct Spark Ignition Controls Technical Bulletin

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.

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.

Installation and

Wiring

Location and

Mounting

G—G76x Direct Spark Ignition Controls Technical Bulletin 7

CAUTION: Equipment Damage Hazard. Connect the high

voltage cable to the spark transformer terminal and

spark electrode before applying power to the control.

Ensure that the ground wire is attached to the sensor

assembly and the ignition control ground terminal

strip.

CAUTION: Equipment Damage Hazard. Locate all limit and

operating controls in series with the thermostat

terminal (THS 2) on the ignition control.

Check the voltage rating marked on the control and make sure it is suited

to the application. Use a National Electrical Code (NEC) Class 2

transformer to provide 24 VAC under maximum load, including valves.

A transformer having excessive primary impedance due to poor coupling

will affect the ignition potential.

Refer to Figure 3 for wiring diagram. All wiring should be in accordance

with the 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 of 6.35 mm (1/4 in.) and are not wrapped around any pipe, other

wiring, or accessory.

Transformer

Thermostat

G76x Ignition Control

SENSE 4

THS 2

M.V. 3

GROUND

LED

Limits in

Thermostat

Line Only

Power

Supply

Main Burner

Ground

Spark Electrode/

Sensor Assembly

Main

Valve

Main

Valve

Figure 3: Wiring Diagram for G76x Ignition Controls

Electrical

Connections

8 G—G76x Direct Spark Ignition Controls Technical Bulletin

Instructions for installing the spark electrode and sensor assembly are

typically provided by the appliance manufacturer. It is important to follow

those instructions. If such information is not included, use the following

basic instructions.

Location/Mounting

The spark electrode and sensor assembly must be positioned for easy

access and securely mounted to the main burner to ensure that the

assembly remains properly positioned with respect to the main burner

flame. The main burner flame must engulf at least 9.52 mm (3/8 in.) of the

flame sensor. If a separate flame sensor is used, keep the sensor wire as

short as possible and do not rest it against grounded metal surfaces.

Standoff insulators are recommended.

The spark electrode, flame sensor, and G76x must share a common ground

with the main burner to operate correctly. Thermoplastic insulated wire

with a minimum rating of 105°C (221°F) is recommended for the ground

wire. Ensure that the flame sensor wire and the high voltage spark

transformer wire 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

accessory.

Spark Electrode

and Sensor

Assembly

G—G76x Direct Spark Ignition Controls Technical Bulletin 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.

WARNING: Fire or Explosion Hazard. Do not attempt to

check out this system by manually lighting the

main burner.

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 the highest 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 off the thermostat.

4. Turn on the gas 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 the highest setting and verify successful

ignition and a normal run condition for at least three minutes. If the

appliance fails to run, see the Service Checkout Procedures section.

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.

9. Return the thermostat to a normal temperature setting before leaving

the installation.

Checkout and

Startup

Procedure

10 G—G76x Direct Spark Ignition Controls Technical Bulletin

The anticipator setting is normally equal to the ignition system current

draw, plus that of the main valve.

Due to variations in appliance wiring and valves, it is advisable to measure

the actual current draw of the heating system at the thermostat location.

Measuring the current draw can be accomplished by opening the

thermostat contacts (lowering the setpoint), and installing an AC ammeter

across the terminals, or by using a clamp-on ammeter with a 10-turn

multiplier attached to the terminals. See Figure 4.

IMPORTANT: Measuring the current with an ammeter will energize

the system. Wait until the appliance is in the run

condition before taking a current draw measurement.

Ten Turns

AC Ammeter Low Scale Setting

Heating

System

Heating

System

Clamp-on Ammeter

(divide reading by ten.)

Figure 4: Measuring the Thermostat Current

Thermostat

Heat

Anticipator

Settings

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