The provided document is an Installation, Operation, and Parts Manual for an AGI Low Temperature Upstream Heater, specifically models GGH-8390 and GGH8390-50, which are VP (Vapor Propane) and NG (Natural Gas)-Fired Heaters.
Function Description
The AGI Low Temperature Upstream Heater is designed for the low-temperature drying and conditioning of farm crops. It is intended for outdoor use only and must be used in conjunction with 1750 rpm centrifugal fans. The heater operates by providing supplemental heat to the airflow generated by the fan, which is then directed into a grain bin for drying. The system includes a fuel train, burner assembly, and a control box to manage ignition, flame, and temperature. The heater is designed to be interlocked with the fan's electrical controls, ensuring it only operates when the fan is running, a critical safety feature.
Important Technical Specifications
The heater models GGH-8390/GGH8390-50 are designed to operate with either vapor propane or natural gas. It is crucial to note that liquid propane should not be used, as it will void the AGI Heater Warranty and can cause serious personal injury and property damage.
Fuel Supply Requirements:
- Vapor Propane (VP) Fuel: Requires a minimum supply pressure of 1 psi (6.9 kPa) to the heater during operation. The gas supply line must be connected to the top outlet of the stationary propane tank to ensure vaporized propane delivery. Storage tanks must be located at least 25' (7,620 mm) from all structures, adhering to local codes. The fuel line between the supply tank and the heater should provide a pressure drop of 1 psi (6.9 kPa).
- Natural Gas (NG) Fuel: Requires a minimum supply pressure of 1 psi (6.8 kPa) and an input rate of 400,000 BTU/hr during heater operation. The inlet supply connection to the heater is 1/2" NPT.
Electrical Specifications:
- The heater requires 3-wire single-phase power: 120V "hot" L1, 0V neutral L2, and ground.
- It must be electrically interlocked to the fan to ensure operation only when the fan is running. AGI fans with starters include an auxiliary electrical contact for this purpose.
- A properly-sized lockout type disconnect box with fuse or breaker protection for EACH fan and add-on heater is required.
- The electrical supply must be 120 Volt and 15 amp rated.
- The heater must be connected to a ground rod, no further than 8' (2.4 m) away, using a minimum 6 AWG solid, bare copper wire.
Orifice Sizes:
The heater is supplied with 0.0938", 0.0625", and 0.1563" orifices. The appropriate orifice size depends on the fan's centrifugal HP and the desired temperature rise. For example, a 10 HP fan with a 2" static pressure and a 10°F temperature rise would use a 0.0625" orifice for propane or a 0.0938" orifice for natural gas.
Temperature Control:
The system can be controlled by Penn & Emerson Electronic Controllers or HONEYWELL Electronic Controllers. These controllers manage the ON/OFF cycle of the heater based on setpoint and differential temperatures, using a plenum temperature sensor (Sensor A) and an ambient temperature sensor (Sensor B).
Usage Features
- Installation: The heater must be installed in a horizontal position with the burner end facing the aeration fan, centered in the fan inlet cone. The aeration fan intake should be at least 12" (305 mm) above ground to prevent debris intake.
- Burner Side Plate Adjustment: The burner side plates are adjustable to optimize burn efficiency and ignition at different burner pressures and airflow rates. Positions include inner (restricts airflow, lower burner pressures), middle, and outer (moderate temperature rise, higher burner pressures).
- Temperature Probe Installation: The temperature probe should be located on the bin wall, below the perforated floor, approximately 6 inches above the concrete floor, and at least 3 ft from the transition.
- Pre-Start Check: Before operation, ensure all electrical and fuel supplies are off, fan blades turn freely, fan guard is in place, heater is free of debris, covers are secure, bin transition is clear, thermostat is working, and the high limit switch is reset if tripped.
- Start-up Sequence: Turn on the aeration fan, then flip the heater toggle switch to "ON." A 15-second pre-purge delay occurs, followed by a 10-second trial ignition period. The solenoid LED light indicates gas flow to the burner.
- Flame Inspection: The flame should be blue with an orange tip, approximately 2" [51 mm] to 1 1/2" [63.5 mm] long. Yellowish, long flames indicate too low airflow, while short, all-blue flames indicate too high airflow, requiring burner side plate adjustment.
- Shutdown: Close the gas shut-off valve at the tank/hydrant, allow the heater to run until the flame burns out to purge gas lines, turn the heater gas valve to OFF, turn off and unplug the heater, and allow the fan to run for at least 2 minutes to cool the heater.
Maintenance Features
- Daily Inspection: Visually inspect the heater for damage, wear, legible safety decals, clear air intake, and tight gas connections and hardware.
- Annual Maintenance:
- Clean debris from the fan, heater housing, and transition.
- Check burner orifices for foreign material and clean with a 3/32" (2 mm) drill bit if necessary.
- Inspect all plumbing and fittings for leaks using a soap and water solution.
- Check all safety valves for gas leaks.
- Inspect wiring for loose connections, bare wires, or rodent damage.
- Check the flame probe for cracked insulation.
- Check spark plug gap (0.07" / 1.78 mm) and clean carbon buildup.
- Ensure the thermostat and other controls are in working order.
- Verify the high-limit switch is not tripped.
- Verify correct flame with no plugged orifice holes.
- Pressure Regulator Maintenance: Ensure the vent screen is clear. Tampering with the regulator voids the warranty; replacement must be performed by a qualified gas technician.
- Solenoid Valve Maintenance: Must be installed and serviced by an approved representative.
- Electrical Maintenance: Electrical components in the control box typically do not require maintenance.
- Troubleshooting: The manual provides a detailed troubleshooting guide for common issues like "No Power," "Burner - No spark," "Burner operates for only a few seconds," and "Excessive fan or heater vibration," with possible causes and solutions. Fenwal-related issues such as input polarity, improper grounding, high resistance, valve malfunction, and igniter malfunction are also addressed.
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