Atlanta Series Geothermal HVAC Control Board
Hardware Highlights
P/N 236-802

Connector Organization

The eight connectors on Atlanta series control boards Atlanta Rev F are grouped intelligently. Careful planning and forethought was used to group connectors by how the wire harnesses will be run and connect to various systems in the heat pump. Wherever needed, 24 VAC and/or common outputs are provided on individual pins and grouped with their associated harness. In other words, the supply and return wires from one harness do not have to run to a second connector or to a separate transformer bus for power or returns. The connectors are grouped like this:

Damper Control

The four damper control relays on the Atlanta series control board supply 24 VAC. Damper outputs are included in the four zone connectors. Each zone based damper control output can drive NO and/or NC dampers. (return to summary page)

Stages and Compressors

Atlanta series control boards are capable of controlling heat pumps of 1, 2, or 3 stages made up of 1 or 2 compressors. Compressors can be single or two speed types, and there is support for 2 single stage compressors. (return to summary page)

System Status LEDs

All inputs and outputs on Atlanta series control boards have LED indicators that use "positive logic". This means that when an input or output is powered, the LED is illuminated, and when an input or output is off, the LED is off. System status LEDs for Atlanta series control boards are green. There are LEDs for each of the following:


  • Y1 in each zone
  • Y2 in each zone
  • O in each zone
  • G in each zone
  • E in each zone
  • Low pressure
  • Medium pressure
  • High pressure
  • External Domestic Hot Water (DHW) request
  • Condensate overflow
  • IrDA active (Yellow)

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  • Damper(s) in each zone
  • Auxiliary function relay
  • E drive
  • F1 drive (single/multispeed fan)
  • F2 drive (multispeed fan)
  • F3 drive (multispeed fan)
  • G drive (variable speed fan)
  • PWM (variable speed fan)
  • Domestic Hot Water (DHW) pump
  • Geothermal loop pump
  • Lead freon compressor
  • Lag freon compressor
  • Reverse valve
  • 24 VAC

Diagnostic LEDs

Diagnostic LEDs are provided to aid the installer, technicians, and even the user of system problems. Diagnostic LEDs are red. Most of them flash while issues are active, and then stay on when the problem has been resolved to give the person diagnosing the problem a visual recording of what problems have occurred. Pressing the reset button on the keyboard turns off diagnostic LEDs on Atlanta series control boards. There are diagnostic LEDs for each of the following:

Dual Microcontrollers

To help prevent damage in the event of failure on the motherboard, the Atlanta series control board uses two microcontrollers. The primary processor handles all inputs, high level functions, and HVAC processes. The secondary processor handles some low level functions, power supply sequencing, clock operations, and monitors the primary processor. If the primary processor locks up or fails to boot, the secondary processor shuts down the outputs on the control board and attempts to restart the primary processor. In that case, outputs on the control board would be inactive until the primary processor becomes active again. (return to summary page)


Atlanta series control boards have a basic keyboard on the lower left corner. Its purpose is to provide a rudimentary interface when a PDA is not available. The keys allow the user to change the run mode, step through test sequences, toggle the freon reversing valve, search for new sensors, and performing soft resets on the primary processor. (return to summary page)

Optically Isolated Inputs

Thermostat wires make very long antennas and can induce high voltages on heat pump control boards. To meet Georgia Controls' high standards for reliability, Atlanta series control boards utilize Transient Voltage Supressors and optically isolated inputs (and in some cases outputs) to protect the motherboard against high voltages from electrostatic discharge and near-strike lightning. For the OEM this level of protection means reduced warranty service calls and claims, thus reflecting well on the OEM's heat pump. For the customer, it means a more robust, reliable, survivable control board that should give many years of quality service without down time. (return to summary page)

Fan Drive Choices

For Atlanta series control boards, Georgia controls includes support for multiple fan drive types. These types cover the most widely used fan motor types used by the industry:

For OEMs, Georgia controls can provide conversions to other, less used fan drives. E-mail or call for more information. (return to summary page)

Auxiliary Function Relays

The Atlanta controllers have one to four auxiliary outputs, depending on the heat pump configuration. As a minimum, one single auxiliary relay ("Aux") is available to perform extra functions. Control boards connected to variable speed fan drives do not use the three F relays. In this case, the unused F relays are available as auxiliary relays as well. This allows OEMs and installers who use the Atlanta series control boards to select any of the following closure outputs to drive external contactors, indicators, etc.:

  • Humidifier drive
  • Stage 1
  • Stage 2
  • Stage 3
  • Freeze LED
  • Service LED
  • Low Pressure
  • High Pressure

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  • High/Low Pressure
  • Lockout LED
  • Freon reversing valve opposite drive
  • Attention required LED
  • Fan on (any speed, any type)
  • Heating on
  • Cooling on

Additionally, the "Aux" relay can be selected to be used for a second water pump drive for use in systems with two domestic hot water systems. Atlanta series control boards can supply two independent hot water tanks/systems in addition to forced air.

For OEMs, Georgia controls can add other auxiliary relay functions. E-mail or call for more information. (return to summary page)

DripCop Condensate Input

DripCop Atlanta series control boards have a micro current condensate sensing system called DripCop. With this, OEMs can put a simple two conductor connector at their desired "full" level of the condensate pan and sense when condensate backs up into the pan with no moving parts. When the DripCop system detects a condensate backup, the Atlanta control board will shut down the compressors immediately and not allow them to come back on until the condensate problem has been addressed. (return to summary page)