I think I have most of this figured out - trying to control the heater from the iAqualink - the iAqualink manual says that the thermostatic circuitry of the heater must be 24VAC to use the Green terminal bar pins 1 and 2 to control the heater. I pulled up the manual for the heater, and while it doesn't specify in writing what the voltage is on the thermostat control board, it does show that the only voltage input is 24VAC. I'm assuming that I can just connect the aqualink 2 wire control method to the external switch / jumper on the heater therm control board and then set the unit for Remote operation, but figured I'd ask here first before toasting anything
Also, when I look at the area for the 3 wire connection on the heater, pool and common connectors are currently not connected, but the spa connector has a blue wire running to it that is labeled 120V - I haven't metered it out with the DVM yet, but anyone familiar with this heater and why only one wire would be connected to the spa input on the thermo board?
Currently, the heater is a stand-alone unit with no external control. You have to use the front panel to select pool/spa and temp.