How does a smart plug measure power?

Yes, the KP125 are to pair with Amazon Alexa’s cloud, Apple Home Kit’s cloud or Google assistant’s cloud. Once connected to their cloud and you already have you google/apple/ Alexa account in home assistant (hubitat)… it pulls the credentials from your google assistant’s cloud.

So after a week of normal use, I was able to see that Sense was “missing” about 3% of my furnace/hvac power usage. A few days were within 0.5% and others were of by as much as 6-7%. The days with high error could be traced to one of two reasons. First, if Sense missed a start/on event, it missed all of the usage for that cycle. Second, Sense has only detected the actual heating cycles (~2 minute sequence of draft fan, ignitor, and main blower). Fan-only operations are not detected. So, I expect my summertime errors would’ve been much higher.

On the power usage side, this application seems to be a pretty good fit for the the HS110. Running watts are between 800 and 1000, with a peak of about 1600 when the main blower starts. With the relay contacts bypassed, I don’t anticipate any issues.