G72x Series Direct Spark Ignition Controls

Transcription

1 Installation Sheets Manual 121 Gas Combustion Combination Controls and Systems Section G Technical Bulletin G72x Issue Date 1299 G72x Series Direct Spark Ignition Controls Figure 1: G72x Direct Spark Ignition Control Description The CE compliant G72x family of controls is designed for direct main burner ignition of natural gas, Liquefied Petroleum (LP) gas, manufactured gas, mixed gas, or LP gas-air mixtures. Application Requirements Following are the application requirements of the G72x control. The G72x can be used on gas-fired equipment with a maximum firing rate of 117 kw (400,000 Btu/hr). Any application greater than 117 kw (400,000 Btu/hr) must have written approval in advance from the Johnson Controls Heating Products Engineering Department. All G72x applications must use a redundant gas valve system with the main valve seats in series. The control does not directly monitor the pressure switch. External circuitry is required on applications that require proof of an open pressure switch before energizing the inducer. All G72x controls have volatile lockout. The G72x control does not contain an independent manual reset function. The application of this type of control is therefore restricted to those appliances where resetting by switching off the heat demand is allowed by European standards. Reset of an appliance in lockout must occur by means of a conscious manual action and not by means of (automatic) devices like thermostats or timers. The ignition connections are not safe to touch. Additional protection against electric shock should be provided by the appliance Johnson Controls, Inc. 1 Part , Rev. Code. LIT

2 Table 1: Specifications Ignition Type Direct Spark Ignition Source High voltage spark, capacitive discharge High Voltage Cable Wire: Stranded Insulation: 25 kvdc minimum rating. Minimum Insulation Temperature Rating: 150 C (302 F) or suitable for the application, whichever is higher. Termination: Appropriately insulated connector to mate with the chosen transformer option. Maximum Cable Length: 1,220 mm (48 in.) Flame Sense Cable Wire: Stranded Minimum Insulation Temperature Rating: 2 G G72x Series Direct Spark Ignition Controls Technical Bulletin 150 C (302 F) or suitable for the application, whichever is higher. Maximum Cable 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 1 second maximum Time Spark Gap 2.5 mm (0.1 in.) nominal Ignition Retrials 0, 2, or 4 Safety Times 4, 6, 8, or 10 seconds* Waiting Times 0, 15, or 30* Inter-waiting Time 30 seconds* Loss of Flame Signal 4 (five total ignition attempts) Retrials Power Requirements Control: Operation Current: 24 VAC, 50 Hz, nominal 0.2A nominal + main valve Contact Rating Main Valve: 2A continuous, 5A inrush Transformer Kema Keur certified to EN Secondary voltage 24 VAC nominal, 50 Hz 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 Options: Control: Spike, Rajah, or 6.35 mm (1/4 in.) male spade 6.35 mm (1/4 in.) male spade 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 EC Certification Number 0063AU1371 Specification Standards EN 298 Standards Complying with the EMC Directive Classification Code AMCVXN Enclosure Degree of IP00 Protection *Timings listed are 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 G72x Series Product Bulletin (LIT ) for necessary information on operating and performance specifications of this product.

3 Operating Mode Definitions rmal Sequence of Operation The following definitions describe operating conditions. Start Signal--The signal from a thermostat that begins the ignition program. Waiting Time--The initial delay between the start signal and the safety time to allow ventilation of the combustion chamber and flue passages to displace any unburned gas and/or products of combustion. Inter-waiting Time--The delay following a failed ignition attempt or loss of flame signal to allow ventilation of the combustion chamber and flue passages to displace any unburned gas and/or products of combustion. Safety Time--The time between energizing the gas valve and de-energizing the gas valve if the flame signal is not detected. Running Position--The main valve remains energized and the spark is de-energized. The appliance is in normal operation under the supervision of the ignition control and its flame detector device. Retrial--Failing an ignition attempt, the control enters the inter-waiting time and then starts another safety time (models with optional retrials). Recycling--The process of automatically repeating a full startup sequence after a safety shutdown (removing the power to the gas valve and igniter). Startup Sequence--The sequence of actions executed by the system that brings the burner from the start to the running position. Volatile Lockout--The safety shutdown of the system where a startup sequence can only begin after the thermostat contacts or main power is cycled. Figure 2 illustrates the sequence of operation of the G72x control. The G72x control is energized upon receiving a start signal from the system thermostat. 1. Waiting Time--If the control has an optional waiting time, the appliance fan or relay is energized through the thermostat contacts. The control delays for the waiting time before continuing to the safety time. 2. Safety Time--The control simultaneously energizes the spark igniter and gas valve in an attempt to light the main burner. During the safety time, the spark igniter is energized until the safety time has elapsed. 3. Running Position--Once a flame signal is sensed at the end of a safety time, the control de-energizes the spark igniter and continues to energize the gas valve until the start signal is removed. G G72x Series Direct Spark Ignition Controls Technical Bulletin 3

4 Abnormal System Operation Undesired Flame Failure to Sense Flame Signal within Safety Time Loss of Flame Signal The G72x offers the following responses based on abnormal system operation. If a flame signal is present at any time it should not be, the G72x allows the flame to extinguish within 30 seconds. If this occurs, the control restarts the normal sequence of operation. If the flame is still present after 30 seconds, the control goes into volatile lockout. During the volatile lockout the gas valve and spark igniter are de-energized and the Light-Emitting Diode (LED) turns Off (models with optional LED). The control remains in this state until the thermostat or the main power is cycled. If a flame signal is not sensed by the end of the safety time, the gas valve and spark igniter are de-energized and if the control has an optional retrial, it starts another safety time after the inter-waiting time. If the flame signal is not sensed by the end of the maximum number of retrials, in any given start signal, the control enters volatile lockout. During volatile lockout the gas valve and spark igniter are de-energized, and the LED flashes (models with optional LED) with a duty cycle of 1 second On and 1 second Off. The control remains in this state until the thermostat or the main power is cycled. If the flame signal is established and then lost in the running position, the gas valve is de-energized and the control recycles through the inter-waiting time. If the flame signal is lost five times in any given start signal, the control enters volatile lockout. During volatile lockout the gas valve and spark igniter are de-energized, and the LED flashes (models with optional LED) with a duty cycle of 1 second On and 1 second Off. The control remains in this state until the thermostat or the main power is cycled. 4 G G72x Series Direct Spark Ignition Controls Technical Bulletin

5 WARNING: Personal Injury Hazard. Avoid personal injury. The G72x ignition control has volatile lockout. The control restarts operation if the thermostat or main power is cycled. Start Flame Present when t Expected Detected Fault Start Signal Flame signal present for 30 seconds? Volatile Lockout (optional LED turns off) Waiting Time Safety Time Main valve flame sensed? Running Position Inter-waiting Time Maximum number of retrials attempted? Loss of flame signal? Start Signal Volatile Lockout (optional LED flashes) Fifth loss of flame signal? De-energize Control and Valves End Figure 2: G72x Sequence of Operation G G72x Series Direct Spark Ignition Controls Technical Bulletin 5

6 Control Timings Figure 3 illustrates the control s timings. rmal Heating Cycle T W T S T R Five Loss of Flame Signal T W T S T R T IW T S Failed Ignition Attempt T W T S T S Legend - Thermostat - Spark Ignition T W T IW - Waiting Time - Inter-waiting Time - Gas Valve T S - Safety Time - Flame Signal T R - Running Position Time - Volatile Lockout Figure 3: Timing Charts 6 G G72x Series Direct Spark Ignition Controls Technical Bulletin

7 Installation and Wiring 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. Location and Mounting WARNING: Shock Hazard. Avoid electrical shock and equipment damage. Disconnect electrical power and turn off gas before wiring control into 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. G G72x Series Direct Spark Ignition Controls Technical Bulletin 7

8 Electrical Connections CAUTION: Equipment Damage Hazard. Connect the high voltage cable to the spark transformer terminal and spark electrode before applying power to the control. Be certain the ground wire is attached to the main burner and 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 transformer capable of providing 24 VAC under maximum load, including valves. A transformer having excessive primary impedance due to poor coupling will affect the ignition potential. te: The transformer must be a safety insulating transformer tested to EN60742 or equivalent, and it must be installed and protected according to the manufacturer s specifications. Refer to Figure 4 for wiring diagram. All wiring should be in accordance with all 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 the high voltage spark transformer cable are separated from one another a minimum of 6.35 mm (1/4 in.) and not wrapped around any pipe, other wiring, or accessories. tes: This unit should be used only in applications that are within the limitations and provisions of the applicable European Union standards. These designs are tested to EN 298 Automatic Ignition Systems standards. 8 G G72x Series Direct Spark Ignition Controls Technical Bulletin

9 Spark Electrode/ Sensor Assembly Main Burner Ground GROUND 5 LED THS 2 M.V. 3 SENSE 4 Main Valve Main Valve High Limit Limits in Thermostat Line Only Ignition Control Thermostat 2 Ampere Fuse Transformer Power Supply IMPORTANT: The G72x ignition control does not respond to a high limit fault with non-volatile lockout. Therefore, a manually resettable high limit switch must be used with the control to meet European agency operating requirements. Figure 4: Wiring Diagram Spark Electrode and Sensor Assembly 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 G72x 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. G G72x Series Direct Spark Ignition Controls Technical Bulletin 9

10 Checkout and Startup Procedure 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 on the thermostat to the highest setting and verify that the control goes through the operating sequence to a shutoff condition. te: 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 on the thermostat to the highest setting and verify successful ignition and a normal running position 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. 10 G G72x Series Direct Spark Ignition Controls Technical Bulletin

11 Thermostat Heat Anticipator Settings 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 this current 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 5. IMPORTANT: Measuring the current with an ammeter will energize the system. Wait until the appliance is in the running position before taking a current draw measurement. To Heating System W R AC Ammeter Low Scale Setting To Heating System W R Ten Turns Clamp-on Ammeter (divide reading by ten.) Figure 5: Measuring the Thermostat Current G G72x Series Direct Spark Ignition Controls Technical Bulletin 11

12 Service Checkout Procedures Preliminary Checks Failure Conditions and Corrective Action 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 the system wired correctly? Is gas inlet pressure per manufacturer s specifications? Is the system powered? Is the start signal from the thermostat present? Is the optional LED flashing? If so, the control is in volatile lockout. Is the optional LED off? If so, the control is not receiving power, or it has detected a fault. Faults are: - flame present, when it should not be, for a period of 30 seconds - a defective control There are three potential system failure conditions: spark present, and system does not work. Spark is present, but main burner does not light. Main burner lights, but does not stay lit. Determine the failure condition, then use the respective flowchart on the following pages to troubleshoot the system. Perform the procedures in the Checkout and Startup Procedure section after any servicing. 12 G G72x Series Direct Spark Ignition Controls Technical Bulletin

13 Start Is 24 VAC available at transformer? Is 24 VAC present from Terminal THS 2 to ground? Is jumper installed from Terminal 5 to ground? Determine why voltage is not present Is power available to primary? Are thermostat contacts and limit control contacts closed? Install jumper Replace the transformer Close contacts Check continuity of wiring to determine why voltage does not exist at Terminal 2 Correct Turn off supply voltage. Is high voltage cable securely attached to spark transformer? Open thermostat contacts for 30 seconds. Close contacts and wait for the waiting time (if applicable). Is spark present now? Replace Is condition of high voltage cable good (not brittle, burnt, or cracked?) System was in volatile lockout. Observe a complete operating cycle to determine why control locked out. Replace G72x control Is spark electrode ceramic cracked or is electrode grounded out? Replace electrode assembly End Figure 6: Spark, and System Does t Work G G72x Series Direct Spark Ignition Controls Technical Bulletin 13

14 Start Is main valve wiring correct and secure? Correct Is 24 VAC present between Terminal 3 and ground during the safety time? Replace G72x control Does continuity exist in wiring to main valve? Replace wiring Is inlet gas pressure per manufacturer s specifications? Correct Is spark gap per manufacturer s specifications and in gas stream? Correct or replace electrode assembly Replace gas valve End Figure 7: Spark Present, but Main Burner Does t Light 14 G G72x Series Direct Spark Ignition Controls Technical Bulletin

15 Start Is flame sensor wiring correct and secure? Correct Does continuity exist in wiring to flame sensor? Replace wiring Is flame sensor ceramic cracked or broken? Replace sensor Is flame sensor clean? Clean sensor with steel wool or replace Does continuity exist between burner and control ground? Add or replace wiring Is flame sensor positioned per the manufacturer s specifications? Correct Is flame sense current > 0.3 microamperes DC? Replace G72x control Correct End Figure 8: Main Burner Lights, but Does t Stay Lit G G72x Series Direct Spark Ignition Controls Technical Bulletin 15

16 Repairs and Replacement CAUTION: Equipment Damage Hazard. Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper and dangerous operation. The G72x controls are not field repairable. Do not attempt field repairs. Use only an exact or factory recommended replacement control. All other accessories, such as flame sensors, electrode assemblies, pilot assemblies, and leads can be obtained through the original equipment manufacturer or a Johnson Controls distributor. Controls Group E. Michigan Street FAN 121 P.O. Box 423 Installation Sheets Manual Milwaukee, WI Printed in U.S.A. 16 G G72x Series Direct Spark Ignition Controls Technical Bulletin