(12-28-2022, 06:06 PM)NewJagsCity Wrote:

(12-28-2022, 01:05 PM)mikesez Wrote: In the US heat pumps are customarily installed with a resistance heating coil in the air handler.  If your air handler is on a 2 pole or 240V breaker, that's why.  The whole thing is sold as a package without explanation of the components.  I would be very surprised if your home did not have this.
Below 40F, the heat pump starts moving much less heat, even though the home needs more.  Below 25F, it moves no heat at all.  Below 32F, there is the possibility of icing over the coils, if the air is humid, which usually makes the thing shut down

All correct.  Once the heat pump shuts down, resistance strip heat coils in your air handler take over.  There are also mechanisms that defrost the heat diffuser (coils) on your heat pump if it ices over.  On my system, when the system auto-sets to heat, at a particular setting, the air handler resistance heat strips come on immediately until the heat pump spins up and takes over the heating load.  This may only occur with variable speed heat pumps.