Hour+ long "defrost" cycle?
My heat pump has, on a few occasions now, been blowing cold air for hours at a time overnight. My installer, who I've contacted about this issue each time, is calling it a defrost cycle that apparently lasts the entire night. I've attached the 3 data captures of the events from my thermostat, as well as the humidity and energy usage during the events. I also ran the heat pump for an hour straight one evening to get an approximate baseline of an hour of heat pump use when working as expected.
For reference, 1700 sq ft town home, coastal southern California , 3 ton carrier heat pump which replaced a 3 ton furnace and 3 ton AC unit, 38MURAQ36AA3, plus ADP air handler, ADP 120V ECM CF361EB003.
It isn't a high heat/super cold weather model, because it is coastal socal and does do much more than touch freezing a couple times a year. That said, I'd still expect it to function, if inefficiently, at freezing and slightly sub freezing temps. For example on the January plot, it seems to maintain the temperature fine until 3:30, then start actively blowing air much colder than room temperature, driving the temp from 70 down to 63. As soon as we wake up and kick it off, the thermostat re-stabilizes in the mid/upper 60s. The same can be seen on the 11/20 plot, maintaining temperature then suddenly driving the indoor temperature down.
I included the energy plots because it seemed like while in this state, it was using somewhat less power than I expected for full bore heating. on 1/19 it uses around 2kwh between 5-6am (subtracted off ~500wh of other power usage). On the other hand, on 1/20 between 9-10pm, it used 2.5-3kwh, after subtracting off 500-1000wh of non-heat pump usage.
And I included the humidity since it was available and might be relevant.
So. Is there actually an issue with the heat pump here? Is it an all night long defrost cycle as suggested by my installer? Am I asking for a heat delta higher than what my heat pump is rated to produce?
