G77x Intermittent Pilot Ignition Controls Product Bulletin

Heating Line Product Guide 435.0Ignition Controls Section

Product Bulletin G77xIssue Date 0600

© 2000 Johnson Controls, Inc. 1Code No. LIT-4350430 www.johnsoncontrols.com

The G77x family of controls is designed for indirectburner ignition and supervision. The G77x is approvedfor ignition of natural gas, Liquefied Petroleum (LP)gas, manufactured gas, mixed gas, or LP gas-airmixtures.

Figure 1: G77x Intermittent Pilot Ignition Control

Features and Benefits

❑ Microprocessor-basedDesign

Provides precise timing and sequencingfunctions

❑ Multiple Trial for Ignitionand Prepurge Timings(Optional)

Offers selectability of timing functions that willbest suit the appliance

❑ Vent Damper Receptacle(Optional)

Allows an electrical interface to vent dampers

❑ Automatic Recycle(Optional)

Eliminates nuisance lockouts by restarting theignition system (after a predetermined delay)if pilot flame is not proven within thetrial-for-ignition time

❑ Rollout Switch (Optional) Ensures that if the rollout switch opens whilethe appliance is operating, the ignition controlgoes immediately into lockout condition

❑ Optional Light-EmittingDiode (LED)

Reduces troubleshooting time by visuallyinforming service technicians of current status

G77x Intermittent Pilot Ignition Controls

2 G77x Intermittent Pilot Ignition Controls Product Bulletin

Application RequirementsFollowing are the application requirements of the G77xcontrol.

• The G77x can be used on gas-fired equipmentwith a maximum firing rate of 117 kW(400,000 Btu/hr). Any application over 117 kW(400,000 Btu/hr) must have written approval inadvance from the Johnson Controls HeatingProducts Engineering Department.

• All G77x applications must use a redundant gasvalve system where the pilot and main valve seatsare in series and opened in sequence forintermittent pilot ignition.

Operating Mode DefinitionsThe following definitions describe operating conditions:� Prepurge: Initial time delay between thermostat

contact closure and trial for ignition.� Trial for Ignition: Period during which the pilot valve

and spark are activated, attempting to ignite gas atthe pilot burner. The control attempts to proveflame at the pilot burner within the trial-for-ignitiontime.

� Run: Pilot and main gas valves remain energizedand spark is turned off after successful ignition.

� 100% Shutoff: For controls with automatic recycle,pilot gas did not ignite within the trial-for-ignitiontime. The control de-energizes the spark circuitand pilot valve.

� Automatic Recycle: If shutoff occurs, the controldelays for a specific recycle delay period beforebeginning another trial for ignition (models withrecycle only).

� Interpurge--Period between trials for ignition whenboth the gas valve and spark are deactivated toallow unburned gas to escape before the next trial.Interpurge occurs between unsuccessful trials on amulti-trial control or after a flameout (if the controlhas an interpurge).

� Ignition Lockout: Pilot gas did not ignite within thefinal trial-for-ignition time. Open thermostatcontacts for 30 seconds, then close to restart thesequence of operation. (Models with an optionalLED will flash the LED to indicate ignition lockout.)

� Flameout: Loss of proven flame.� Hard Lockout: The control detected a fault. Open

thermostat contacts for 30 seconds, then close torestart the sequence of operation. (Models with anoptional LED will turn off the LED to indicate a hardlockout.)

Sequence of Operation

Figure 2 illustrates the sequence of operation of theG77x control.

The control is energized on a call for heat from thesystem thermostat. (Models with an optional LED willturn on the LED [steady on] until the call for heat issatisfied.) The vent damper, if used, is energized andwhen fully opened, also energizes the ignition control.If the control is equipped with the optional prepurge,the appliance prepurge fan or relay is also energizedthrough the thermostat contacts. In the prepurgemode, the control will delay for the time selected(e.g., 15 seconds) before simultaneously opening thepilot valve and supplying a continual spark at the pilotburner. If prepurge is not selected, the pilot valve isopened and spark initiated within one second after thecall for heat.

Under normal conditions, the pilot burner gas igniteswithin the trial-for-ignition time (e.g., 8 seconds), thepilot flame sensor detects pilot flame and signals thecontrol to energize the main valve. The main gas valvewill not be energized until the flame sensor detects thepresence of pilot flame. The spark will continue untilflame is sensed at the pilot burner or thetrial-for-ignition time has elapsed, whichever occursfirst. If the pilot flame is not sensed before the end ofthe trial-for-ignition time, the control may:

• proceed to interpurge, followed by another trial(three trial models whose first two trials producedno flame)

• proceed to a lockout (no automatic recycle modelswhose final trial produced no flame)

• proceed to a recycle delay period followed byanother trial (automatic recycle models whose finaltrial produced no flame)

If the pilot burner flame extinguishes during the runstate (flameout), the control de-energizes the pilot andmain gas valve for the interpurge period. After thisperiod, another trial for ignition is initiated. If theflameout cycle repeats for a total of 16 times (pilotburner flame established then lost), the control will:

• Enter the lockout mode if the control is aG770/G777. The thermostat contacts must beopened for 30 seconds and then closed to escapethe lockout condition.

• Enter the shutoff mode and recycle period(5 minute recycle delay for the G775/G779 and60 minute recycle for the G776/G778) beforebeginning another trial for ignition, starting withprepurge.

G77x Intermittent Pilot Ignition Controls Product Bulletin 3

No Yes

Yes

NoMaximum

number of trialsattempted?

Yes

No

Yes No

Yes

No

Yes

De-energizecontrol and valves

No

Sixteenthflameout?

Control withignitionrecycle?

Ignition lockout(optional LED

flashes)

Yes

No

Recycle delayperiod Shutoff

Flame present whennot expected

Hard Lockout(optional LED

turns off)

Start

Thermostatcall for heat

Prepurge

Flamepresent for

30 seconds?

Detected fault

Trial forignition

Pilotflame

sensed?

Energizemain valve Run

Thermostatcalling for heat?Flameout?Interpurge

End

Figure 2: Sequence of Operation


Mounting

Choose a location that provides the shortest, directcable route to the spark electrode, pilot burner/igniter-sensor assembly. Easy access to the terminals isdesired for wiring and servicing.

The control may be mounted in any position. Refer toFigure 3 for mounting dimensions and Figures 4through 8 for wiring diagrams.

Two Holesfor No. 8 Machineor No. 6 Sheet MetalMounting Screws

562.22

672.63

582.28

512.00

783.06

341.33

SENSE 4

M.V. 3

THS 2

5

GROUND

60.22

60.22

200.77

80.31

1084.25

1164.57

1204.70

4.10.162

60.25

Spade Terminals

1

Add 13 mm (0.50 in.) forRajah type connector.1

P.V. 1

Figure 3: Mounting Dimensions, mm (in.)


W iring Diagrams

Vent Damper System

Thermostat

Ignition Control

PLU

G

GROUND

5

24 V

LED

THS 2

PV 1

MV 3

Transformer

MainValve

PilotValve

Main BurnerGround

Pilot BurnerAssembly

IntegralIgniter/Sensor

Vent DamperWiring Harness

PowerSupply

Limits in ThermostatLine Only

PilotGas Supply

Figure 4: Wiring Diagram for Integral Spark/Sense with Vent Damper

Thermostat

PLU

G

GROUND

524 V

LED THS 2

PV 1

MV 3

Transformer

Pilot BurnerAssembly Integral

Igniter/Sensor

Main BurnerGround

PilotGas Supply

Ignition Control Limits in ThermostatLine Only

PilotValve

MainValve

Figure 5: Wiring Diagram for Integral Spark/Sense without Vent Damper


Flame Sensor

Thermostat

Vent Damper System

Transformer

PL

UG

5 24 V LED

THS 2

PV 1

MV 3SENSE 4

GROUND

Ignition Control Limits in ThermostatLine Only

PowerSupply

Vent DamperWiring Harness


Main BurnerGround

PilotGas Supply

PilotValve

MainValve

Figure 6: Wiring Diagram for Separate Spark/Sense with Vent Damper

Flame Sensor

Thermostat Transformer

PLU

G

5 24 V LED

THS 2

PV 1

MV 3SENSE 4

GROUND

Ignition Control

PilotValve

MainValve


PowerSupply

Main BurnerGround

PilotGas Supply


Figure 7: Wiring Diagram for Separate Spark/Sense without Vent Damper


Main BurnerGround

PilotGas Supply


Flame Sensor


Thermostat Transformer

PowerSupplyMain

ValvePilotValve

RolloutSwitch

Ignition Control

SENSE 4MV 3

PV 1R1R.O. SWH

THS 2

5

GROUND

Figure 8: Wiring Diagram for G77x with Rollout Switch Terminal

Rollout Switch Function

The rollout switch is wired into the G77x ignition controlat Terminal R1 (see Figure 8). The rollout switch(a normally closed set of contacts) is positioned todetect flames rolling out of the combustion chamber.If rollout occurs, the switch contacts open and theG77x immediately goes into a lockout condition,closing the main and pilot valves so that the system isnot allowed to function.

The thermostat contacts must be opened for30 seconds, and then closed to escape the lockoutcondition. When the rollout switch contacts havereturned to the closed position, the G77x will start itsoperating sequence when the thermostat contactsclose.


Ordering Information

G 7 7 _ _ _ - _ _

Customer-specific Requirements(i.e., LED, Spark Transformer Type,Case Temperature Rating, Special Label,Miswire, Alarm Contact, Flame FailureResponse Time, Spike Tip Bore, etc.)

Letter

A =B =C =D =

0 second30 seconds4 seconds15 seconds

*

G =H =J =K =

LetterWith DamperReceptacle?

With RolloutSwitch?

NoYesNoYes

NoNoYesYes

*Requires special setup.

3333311111

A =B =C =D =E =K =L =M =N =R =

Letter Number of Trials Trial-for-Ignition Time Interpurge Time

8 seconds25 seconds50 seconds85 seconds120 seconds8 seconds25 seconds50 seconds120 seconds85 seconds

30 seconds**30 seconds**30 seconds**30 seconds**30 seconds**15 seconds**15 seconds**15 seconds**15 seconds**15 seconds**

** During the flame stabilization period, interpurge time is 0. Interpurge time is always 0 for models with a rollout switch.

Number

0 =5 =6 =7 =8 =9 =

No Recycle/Remote Sense5 Minutes/Remote Sense60 Minutes/Remote SenseNo Recycle/Integral Sense60 Minutes/Integral Sense5 Minutes/Integral Sense

Prepurge Time

_

Recycle Time/Flame Sense

Note: Timings listed are for 60 Hz operation. Timings increase by 20% under 50 Hz operation.

The presence of a particular construction in this information does not guarantee its availability.Consult Johnson Controls for available constructions.

Figure 9: Ordering Matrix


Notes


Specifications

Product G77x Intermittent Pilot Ignition Control

Ignition Type Indirect

Ignition Source High voltage spark, capacitive discharge

High Voltage CableMaximum Length 1,220 mm (48 in.)

Flame Sense CableMaximum Length 1,220 mm (48 in.)

Flame Detection Means Flame rectification

Flame Detection Types Integral and remote

Minimum Flame Current 0.15 microampere

Flame Failure ResponseTime

0.8 second maximum1.5 seconds maximum (G776_ G models only)

Spark Gap 2.5 mm (0.1 in.) nominal

Ignition Trials 1 or 3

Ignition Trial Times 8, 25, 50, 85, or 120 seconds*

Prepurge Times 0, 4, 15, or 30 seconds*

Interpurge Times 0, 15, or 30 seconds*

Power Requirements Control: 24 VAC, 50/60 Hz, nominalOperation Current: 0.2A nominal + valves

Contact Ratings Main Valve: 2A continuous, 5A inrushPilot Valve: 2A continuous, 5A inrush

Ambient Operating andStorage Temperature

-40 to 70°C (-40 to 160°F) standard models-40 to 80°C (-40 to 176°F) high temperature models

Humidity 95% RH non-condensing

Wiring Connections Spark: Spike, Rajah, or 6.35 mm (1/4 in.) male spadeControl: 6.35 mm (1/4 in.) male spade

4.76 mm (3/16 in.) male spade optional

Type 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 164933-1073441Australian Gas Association Certificate Number 4524 (G770 models only)

Specification Standards ANSI Standard Z21.20, Z21.20a, Z21.20bCAN/CSA-C22.2 No. 199

*Timings listed are for 60 Hz operation. Timings increase by 20% under 50 Hz operation.

The performance specifications are nominal and conform to acceptable industry standards. For application at conditions beyondthese specifications, consult the local Johnson Controls office. Johnson Controls, Inc. shall not be liable for damages resultingfrom misapplication or misuse of its products.

Refer to the G77x Series Technical Bulletins (LIT-121250, LIT-121261, and LIT-121263) for necessary information on the installation, use,and servicing of this product.

Controls Group www.johnsoncontrols.com507 E. Michigan Street FAN 435.0P.O. Box 423 Heating Line Product GuideMilwaukee, WI 53201 Printed in U.S.A.

G77x Intermittent Pilot Ignition Controls Product Bulletin

Documents

Transcript of G77x Intermittent Pilot Ignition Controls Product Bulletin