I agree with glort!
Regarding the fan on your setup, does it run all the time or is it thermostatically controlled? If it runs all of the time, do you have a speed control on it? I'm wondering what the power source is, the z winding or 110v?
The fan is powered by a 12v power supply. The power supply was a Chinese unit, but it failed rather rapidly. So the current setup uses a transformer, rectifier and capacitor setup to make 12V. Stone reliable. It is, of course, powered by a 115V leg of the generator, as is my Grundfos water pump.
The fan runs all the time, as does the water pump. The water temperature will be as low as 170 with no load, and 210 at full load. No thermostat. I've never been able to overheat it. And I rarely run it with no load.
I do not use the Z winding for anything.
Given the choice, I'd pick a better quality generator head. The ST head has been a bit of a battle and I'm not sure I've worked out all the bugs.
Interestingly, when I first fire the unit up, the lights flicker like crazy, despite my best efforts. After a few hours, the flicker is reduced to tolerable levels. Maybe if I get time, I'll put the O-scope on it after startup and after a few hours and compare.
For now, power is back on and the listeroid is back in silent mode. (the neighbors loved seeing it run, BTW! )
Remember, I did install a capacitor bank on the field to smooth out the sine wave, which it did. I also installed a "Georgia Generator" AVR that runs from a single main winding. That brought voltage up from 109 to 125, thank goodness. As 109 would drop into the 90's under heavy load, which left everything groaning in the house. Now it drops to 111 under full load. Possibly because that particular leg is not the sensing leg for the AVR. But it's rare to be at full load for long.
I did run central AC, well pump, water heater and more all at the same time. Laundry, dishwasher and gas dryer were quite busy. No issues and no overloads.