Jandy AquaLink RS Heater Integration: Connection and RS-485 Troubleshooting

How the Heater Connection Works

The AquaLink RS does not directly power the heater. Instead, it provides a low-voltage (24 VAC) signal through the 10-pin terminal bar that acts as a thermostat call. This signal is wired in series with the heater's existing safety circuit, similar to how a fireman's switch or heater delay would be wired.

When the AquaLink RS determines that heating is needed (water temperature is below the setpoint and the system is in the correct mode), it closes the low-voltage circuit on the heater terminals. The heater sees this as a thermostat call and fires. When the setpoint is reached, the AquaLink RS opens the circuit and the heater shuts down.

Because the heater's own thermostat must be set to maximum and its toggle switch must be ON, the AquaLink RS takes full control of when the heater fires. The heater's built-in safety circuits (high limit, pressure switch) remain active and will shut down the heater independently if needed.

Step-by-Step Heater Wiring

Connecting a Jandy brand heater

1. Run two #14 gauge wires (rated for hot environments) from the proper terminals on the green 10-pin terminal bar to the heater. See Figure 4 in the manual for the exact terminal positions.
2. At the heater end, wire nut the two wires in series with the heater circuitry, as if you were wiring a fireman's switch or heater delay.
3. A factory-installed wire loop exists on terminals 1 and 2 of the 10-pin terminal bar. Remove this loop before connecting the heater wires.
4. Set the heater thermostat to the Spa position and maximum setting.
5. Turn the heater toggle switch ON.
6. Do not disconnect the heater's high limit or pressure switches.

Connecting a spa heater

1. For a separate spa heater, make the connection to the Spa Heater Interface Board and plug it into the Spa Heater socket on the PCB.
2. The spa heater relay socket is located on the PCB per the wiring diagram.

Shared heater setup (dual equipment)

1. For dual equipment systems sharing one heater, set S1 DIP #6 to ON.
2. Plug the JVAs into the Intake, Return, and Cleaner JVA sockets.
3. Apply the correct bezel decal over the existing decal to identify the HEATER and VALVE buttons correctly.
4. Plumb according to Figure 2 in the manual, with check valves and JVAs in the correct positions.

Troubleshooting Heater Issues

Heater does not respond to AquaLink RS commands

1. Verify the heater thermostat is set to maximum and the toggle switch is ON. If either is in the wrong position, the heater will not respond to the AquaLink RS call.
2. Check the low-voltage wiring from the 10-pin terminal bar to the heater. Use a multimeter to measure 24 VAC across the heater terminals when a heat call is active. If voltage is present but the heater does not fire, the problem is at the heater end.
3. Verify the factory wire loop on terminals 1 and 2 was removed. If the loop is still in place, the heater circuit may be permanently closed or the wiring may be incorrect.
4. Check that the #14 gauge wires are properly connected at both ends. Loose wire nuts are a common failure point, especially in hot and vibrating environments near the heater.

Heater fires but does not reach setpoint

1. Verify the water temperature sensor is reading correctly. An inaccurate sensor will cause the AquaLink RS to misjudge when to call for heat and when to stop. See the sensor errors guide for testing procedures.
2. Check that the heater is sized appropriately for the pool or spa volume. An undersized heater may not be able to overcome heat loss.
3. Verify the filter pump is running when the heater is active. The AquaLink RS should be configured to ensure the pump runs during heat calls.

DIP switch settings for heater types

• Gas heater (default): S1 DIP #8 OFF. After the thermostat setpoint is reached, the heater remains OFF for 3 minutes before it can fire again. S1 DIP #4 OFF enables heater cool-down (pump continues running after heater shuts off to dissipate residual heat).
• Heat pump: S1 DIP #8 ON. After setpoint is reached, the heater remains OFF for 5 minutes. S1 DIP #4 can be turned ON to disable cool-down since heat pumps do not retain residual heat.
• Electric heater: S1 DIP #4 ON to disable cool-down (no residual heat). S1 DIP #8 setting depends on whether you want the 3-minute or 5-minute off-cycle delay.

RS-485 heat pump communication

1. For RS-485 controlled heat pumps, verify the communication cable is properly connected between the AquaLink RS PCB and the heat pump.
2. Set S2 DIP #1 to ON for heat pump priority mode.
3. Confirm the heat pump is in remote/automation mode, not local/manual mode.
4. Check for proper termination of the RS-485 bus if there are multiple devices on the communication line.

Common Parts That Fix This Problem

• #14 gauge wire rated for hot environments (for heater connection runs)
• Wire nuts rated for the wire gauge and temperature environment
• Spa Heater Interface Board (for spa heater connections)
• Replacement 10-pin terminal bar (if terminals are damaged or corroded)
• Bezel decal for shared heater configuration