Power boiler by a generator -- via an online UPS: "Poor Ground"
We are cursed with a "high efficiency" boiler, that not only requires electricity to work, it also extremely picky about the current quality...
I'm trying to make it work off of our new Diesel generator -- so that, when the lights go out after the next hurricane, we could have heat and hot-water... It was hard-wired to the breaker originally, but I inserted a computer's power-cord in there, which is plugged into a wall-socket -- in case of an outage, I can plug that same tail into an alternative power-source.
Although all our other devices (refrigerators, computers, TVs) work just fine with the generator-provided current, the boiler kept refusing to work, complaining about "Wiring Fault" or some such.
In an attempt to appease it, I purchased an online UPS (Eaton PW9130-700). An online UPS, when not in "efficiency mode", will run its own inverter off of the battery at all times -- using the incoming power only to charge the battery, thus isolating the load from any impurities of incoming current. Its output, even when plugged into the fluctuating generator, is a perfectly steady 120V, 60Hz.
And the boiler likes that -- well enough to not complain about any "Wiring Fault". Now the complaint is: "Poor Ground" and I'm at a loss as to what that could possibly mean... I connected the generator's ground-contact to the grounding hole of the nearest house outlet (just to test). I then, independently, connected the ground-prong of the boiler's cord to a copper wire running into (wet) ground -- same complaint. Finally, I stuck that same copper wire into the ground "hole" of another house outlet (the same, that the boiler is normally plugged in now) -- same problem...
How do I solve this? Thank you!