Hi Zesty.
The WFP Link radio remote controllers and the Stand alone radio remote controllers are controlling the delivery pump out to the reel and giving the flexibility to adjust Flow and Pause flow. We have produced V16 HW controllers that can switch a Heater and have frost protection. Many of the distributors use these when making a Hot water system. Pausing the delivery pump does'nt stop the heater. Most hot Boxes have a header tank and the heater has its own pump to circulate water through the heater and header tank and exchange plates as Spruce has commented.
The Controller is switching the Heater via signal cable (purple)
https://www.youtube.com/@springeuropeltd7880/videosWhen we could get Bluetooth modules just before the world went mad we have made V16 WFPL HW and via the app the heater can be switched separately form pausing the pump. (Currently we would make V16 WFPL HW XBT (no bluetooth) if ordered)
As long as i have not miss understood. If you bought a Hot box that already has a V16 HW, You can add the One Shot stand alone as now between the HW controller and pump on the Brown cable. Or If you have a Controoler with WFPL you could as some choose to just leave your existing controller to manage the delivery pump and have the V16 HW in the Hot box to just switch the heater, use frost protect and monitor temperature.
Cheers