I know it sounds like a delicious dish, but after getting a heat pump installed, it went unresponsive after the tech left. No lights or sounds at all, and on further inspection the voltage range monitor had an alarm set. It was reading 254V on the 240V line, and as the heat pump had a maximum rated voltage of 253V, it correctly shut off power to protect it.
After checking with the installing technician I reported a voltage problem to DTE, who promptly sent a tech who measured the 120V line with a multimeter (!) and pronounced it 123V, which is in-spec. (115V – 125V) So now I’ve learned that a bog-standard multimeter can handle AC voltages and not just like, 24V. Which I probably should have known. Anyway the tech had definitely established it wasn’t actually their problem so he left. (Sorry!)
After some dilly-dallying with whether the monitor supported a calibration mode present in the PDF manual but not the printed one that came with it, I ended up increasing the minimum and maximum cutoffs up by 4V, as matching what I measured with multiple multimeters. Once I did so, it immediately clicked, cleared its alarm light, and it’s been stable since! Neat.
