You need to switch to SPA mode to isolate the water to just heat the spa.
When you switch to SPA mode you should stand by the equipment pad and observe that both the suction actuator and return actuator move their valves. If only one or none turn you have problems with the actuators.
I think NO DEMAND means there is no request for heat from the Aqualink. You need to enable the heater and set a temperature above the water temperature for heat.