I have solar heating for the pool, but a 11KW electric just to bump up the spa 10 degrees or so. I know the SWG is wired to the pump timer, but is the heater typically done this way also? I can't find much info on the Hayward heater, but I assume if it is wired direct to 220V and you turned it on, it would just heat the water inside the unit and cycle off and on relatively often. However, if it is wired to the timer, it would help make sure water is flowing before it is operated - assuming there is no bypass. I also want to have it on the spa return line only so that it can't accidently heat the entire pool which would probably cost a small fortune.