The H310s work fine in my freezers, and accurately report the temperature as it swings from -10°F to about 4°F. I really needed these to alert me if the temperature rises too high, like to 20°F. But...

@Daryl Anderson I'm also a EE, have wired about 7 HS switches, and have one with an identical problem. I have the HS210 (HW 2.0, FW 1.1.5) connected to the hot end of the 3-way circuit, and when I...