And here is the same set of shifting correlations for the upstairs system, with the Ecobee runtime variable “CoolUp”
For Sep-Oct’17, CoolUp is well correlated with device AC, plus partially correlated with device ACSpike. AC runs just a little over 3kW, while ACSpike is about 400W.
The upstairs AC usage pretty much stops for Nob’17-Feb’18, but shows up enough in Mar’18 to look at the charts again (the upstairs gets warmer in the sun, much more quickly than downstairs).
With the start of the new cooling season, AC and ACSpike are still closely correlated with CoolUp.
But as we roll into May’18, device ACDown begins to correlate more closely with CoolUp. Is it just correlation because both AC units are running or is there real causation ??
That seems to get answered in Jun-Jul’18, when ACDown has much denser correlation with CoolUp than AC, which is zeroed out for much of the CoolUp runtime.
Oddly, as we get into Aug’18, AC3 and possibly AC4 take over association with CoolUp runtimes, as ACDown and ACSpike reconnect with CoolUp.
My take on all this correlation shifting is that my two real AC devices, which are both 20 year old single-stage Bryant Seer 11.5 units, must have varying signatures with the seasons.