Honeywell ST7997 User's Manual
Contents
1. 1204 Honeywell Home and Building Control Honeywell Inc Honeywell Plaza P O Box 524 Minneapolis MN 55408 0524 69 1204 G R 8 98 Home and Building Control Honeywell Limited Honeywell Limit e 155 Gordon Baker Road North York Ontario M2H 3N7 www honeywell com2. Honeywell ST7997 Oil Burner Mounted Electric Fan Timer APPLICATION The ST7997 Oil Burner Mounted Electric Fan Timer integrates control of burner and circulator fan operations in an oil furnace and is the central wiring point for most electrical components in the furnace The ST7997 mounts on a standard four inch by four inch junction box typically located on the oil burner When used with the R7997 Integrated Oil Primary Controller and Ignitor it provides simplified wiring and field serviceability The basic purposes of the ST7997 are to monitor the thermostat for heat cool and fan demands run the oil burner primary control and run a two speed circulating fan as required The ST7997 also monitors a limit switch string that energizes the circulating fan when the limit switch opens The ST7997 provides electronic air cleaner EAC and humidifier HUM terminal connections for field installation convenience SPECIFICATIONS Electrical Input Ratings Supply Voltage 102 to 132 Vac 120 Vac nominal 60 Hz Supply Current 100 mA maximum without loads connected to outputs 20A maximum with loads connected to outputs Output Ratings Relay Contacts Circulator Heat or Cool Blower Speed Rating 15A Full Load Amperage FLA 0 75 pF 30A Locked Rotor Amperage LRA 0 5 pF NOTE FLA rating is reduced by EAC load EAC 1A maximum Circulator Continuous Blower Speed Rating 8A FLA 0 75pF 16A LRA 0 5pF H
3. M12920 Fig 1 ST7997A B Oil Burner Mounted Electric Fan Timer dimensions in in mm Mounting Mounts directly on standard 4 in 102 mm by 4 in 102 mm junction box Packaging Unit pack and bulk pack Connections R7997 Oil Burner Motor Oil Valve and Power L1 L2 Six 6 1 4 in 6 mm by 1 32 in 0 8 mm quick connects pass through recessed cover on bottom of case Circulator Blower Neutral Heat Cool Continuous Limit Hot Limit One six position Molex in line connector flush with top of case or six 1 4 in 6 mm by 1 32 in 0 8 mm quick connects individually recessed in top of case Humidifier Two 1 4 in 6 mm by 1 32 in 0 8 mm quick connects individually recessed in top of case Electronic Air Cleaner Two 1 4 in 6 mm by 1 32 in 0 8 mm quick connects individually recessed in top of case Thermostat Cooling Contactor Four No 4 screw terminals marked Rc Y G and C on front side of case INSTALLATION When Installing this Product 1 Read these instructions carefully Failure to follow them can damage the product or cause a hazardous condition 2 Check the ratings and specifications given in the instructions and on the product to make sure the product is suitable for your application 3 Installer must be a trained experienced service technician 4 After installation is complete check out the product operation as provided in these instructions 69 1204 A WARNING Elec
4. NTACTOR L2 L1 GND lt lt SCREW TERMINAL BURNER MOTOR 1 4 IN QUICK CONNECT M12924 Fig 3 ST7997 Oil Burner Mounted Electronic Fan Timer standard wiring connections 3 69 1204 ST7997 OIL BURNER MOUNTED ELECTRIC FAN TIMER HUMIDIFIER EAC LIMIT LINE FURNACE LIMIT VOLTAGE CIRCULATOR BLOWER R7997 INTEGRATED OIL PRIMARY WITH BLOWER DELAY G oo lt a E Fo e Limi THERMOSTAT 2 5 WIRE ISOLATION CONTROL ELECTRONICS gt ac aS af 8 COMPRESSOR CONTACTOR 1 L2 L1 i GND SCREW TERMINAL 1 4 IN QUICK CONNECT M12922 Fig 4 ST7997 Oil Burner Mounted Electronic Fan Timer wiring for units with pre and post purge NOTE Two dummy quick connect terminals labeled unused wires not connected to the ST7997 circuitry are provided on the back of the case to hold unused wires from the circulation blower motor speed taps IMPORTANT Field changes to the speeds low medium low medium high high of the ST7997 blower modes heat cool or continuous fan can be made to models using Molex connectors by cutting speed wires and splicing in an unused lead in accordance with local and national codes 69 1204 Wiring Options Wiring options are listed in Table 1 Setting the Heat Fan Off and Heat Fan On Delay S
5. heat or cool speed of the circulating fan is energized for 120 Vac electronic air cleaner EAC connections are not energized when the optional continuous fan terminal is energized NOTE If continuous fan option is selected connect EAC to line voltage input L1 Humidity control is connected Humidifier connections are energized when burner motor is Optional connectors are available energized on standard models and when oil valve is for 120 Vac humidifier energized on purging models 69 1204 ST7997 OIL BURNER MOUNTED ELECTRIC FAN TIMER HEAT OFF DELAY TIME HEAT ON DELAY TIME 120 150 eines IS SWITCH HANDLE POSITION A FOR SELECTED MODELS ONLY M12918 Fig 6 ST7997 Fan Timer location and settings for Heat Fan Off and Heat Fan On delay switches 69 1204 CHECKOUT Verify system operation by running the system through one complete heating and cooling cycle if applicable Troubleshoot by checking for appropriate voltages at the ST7997 terminals controlling the burner motor and heat and cool circulating fan The ST7997 schematic Fig 3 shows internal switching to clarify operation and assist in troubleshooting Table 2 provides the ST7997 operating sequence Use the green diagnostic LED to assist in troubleshooting a Off when system is on and thermostat is satisfied b Oncontinuously when ST7997 recognizes a valid call for cool or fan from the thermostat and or a valid call fo
6. operation is selected at the thermostat Oil primary control locks out within lockout timing timing depends on oil primary control Burner motor is de energized and LED turns off even though the thermostat is still calling for heat If heat fan has started it continues through the selected heat fan off delay period Burner motor is de energized LED turns off and oil primary control goes into recycle mode If selected heat fan off delay timing is longer than the recycle delay timing the heat fan continues to run through the next trial for ignition Cooling contactor is energized and LED turns on immediately Circulating fan is energized at cool speed when cool on delay time is complete Cooling contactor is de energized and LED turns off immediately Circulating fan turns off when cool fan off delay time is complete Circulating fan is energized immediately at heat speed and LED turns on immediately Circulating fan is de energized and LED turns off immediately LED flashes at 2 Hz rate 1 4 second on off Oil primary control shuts off burner Circulating fan is energized immediately at heat speed Oil primary control is energized initiating burner lightoff and LED changes to continuously on Circulating fan continues to operate at heat speed LED turns off Circulating fan turns off when heat fan off delay time is complete Normal operation resumes device is in standby awaiting next thermostat command 7 69
7. r heat from the R7997 c Blinks rapidly on and off when limits are opened ST7997 OIL BURNER MOUNTED ELECTRIC FAN TIMER Table 2 ST7997 Operating Sequence Mode Action System Response Thermostat calls for heat W terminal is energized Thermostat ends call for heat W terminal is de energized Burner fails to light Established flame fails Thermostat begins call for cool G and Y terminals are energized Thermostat ends call for cool G and Y terminals are de energized Thermostat begins call for fan G terminal is energized Thermostat ends call for fan G terminal is de energized Limit switch string opens Limit switch string closes with existing call for heat Limit switch string closes without existing call for heat Thermostat calls for heat closes oil primary control T T connections Ignition system and oil primary control start the furnace Oil flows as long as oil primary senses flame Burner motor is energized LED turns on and heat fan on delay timing begins When timing is complete the circulating fan is energized at heat speed and warm air is delivered to the controlled space Oil primary control is de energized terminating the burner cycle and LED turns off Heat fan off delay timing begins When timing is completed the circulating fan is de energized ST7997 returns to standby mode oil primary control and circulating fan are off unless continuous fan
8. trical Shock Hazard Can cause serious injury or death Disconnect power supply before wiring to prevent electrical shock or equipment damage Location and Mounting Mount the ST7997 on the oil burner 4 in 102 mm by 4 in 102 mm junction box compartment using four No 6 screws obtained locally See Fig 2 M12919 Fig 2 ST7997A B Oil Burner Mounted Electric Fan Timer typical installation IMPORTANT The ST7997 requires a mechanical or electronic power stealing or battery powered five wire thermostat with independent heat cool circuits R W Rc Y G Wiring All wire must comply with local codes and ordinances Refer to Fig 3 for standard wiring connections and Fig 4 for units with pre and post purge Make wiring connections within the oil burner junction box for applications requiring power venting Add a 4 in by 4 in 102 mm by 102 mm junction box at least 1 2 in 13 mm deep between the ST7997 and the oil burner junction box See Fig 5 for wiring diagram showing airflow switch and power vent motor 577997 OIL BURNER MOUNTED ELECTRIC FAN TIMER CIRCULATOR BLOWER HUMIDIFIER EAC LIMIT LINE VOLTAGE n 2 E R R7997 INTEGRATED RG OIL PRIMARY WITHOUT BLOWER DELAY Y HEAT CALL o E LIMIT THERMOSTAT BEJE CONTROL SWIRE ELECTRONICS OIL PRIMARY lt BURNER VALVE 577997 COMPRESSOR CO
9. umidifier 1A maximum Molex is a registered trademark of Molex Incorporated Copyright 1998 Honeywell Inc All Rights Reserved INSTALLATION INSTRUCTIONS Limit 10A maximum L1 L2 Burner 20A maximum Thermostat Current Heat Mode 100 mA R7997 supplied Cool Mode Cooling contactor load 500 mA maximum ST7997 supplied Cooling Contactor 2 VA minimum 12 VA maximum Molex is a registered trademark of Molex Incorporated Fuse 1A automotive type ATO Delay Timings Heat On Delay 45 or 60 seconds fixed or field selectable via DIP switch optional position 3 Heat Off Delay 60 100 120 150 seconds four field selections via DIP switch positions 1 and 2 Cool On Off Delay 0 0 or 30 30 seconds fixed Delay Timing Tolerances 5 seconds or 20 percent whichever is greater Environmental Temperature Ranges Operating 40 F 40 C to 150 F 66 C Storage 20 F 29 C to 150 F 66 C Humidity 90 percent relative humidity at 95 F 35 C noncondensing Approvals Underwriters Laboratories Inc Component Recognized File 353 Canadian Underwriters Laboratories inc Component Recognized Pending approval Mechanical Dimensions Fig 1 4 9 32 in 109 mm long by 4 1 4 in 108 mm wide by 3 27 32 97 mm high See Fig 1 69 1204 ST7997 OIL BURNER MOUNTED ELECTRIC FAN TIMER AELS
10. witches Set the Heat Fan Off delay switches to 60 90 120 or 150 seconds See Fig 6 The off delay time starts when the burner motor is de energized at the end of a thermo stat call for heat 577997 OIL BURNER MOUNTED ELECTRIC FAN TIMER CIRCULATOR BLOWER HUMIDIFIER EAC LIMIT LINE VOLTAGE CONTINUOUS UNUSED WIRES R7997 INTEGRATED OIL PRIMARY WITH BLOWER DELAY i G o Z 5 CONTROL SWIRE ELECTRONICS gt 29 2 2 as COMPRESSOR Vy 1 12 L1 GND AIR FLOW SWITCH SCREW TERMINAL 1 4 IN QUICK CONNECT BURNER MOTOR M12923 Fig 5 ST7997 Oil Burner Mounted Electronic Fan Timer airflow switch and power vent motor for power venting wiring Table 1 ST7997 Wiring Options Mode System Response OPTIONS Constant circulating fan is Circulating fan is energized at low speed when there is connected Optional connectors are no call for heat cool or fan available for separate circulating fan If fan operation is required by a call for heat cool or speed tap fan the ST7997 switches off the continuous fan speed tap before energizing the other fan speed Electronic air cleaner is connected Electronic air cleaner EAC connections are energized when Optional connectors are available the
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