Heat Pump switch-over temperature? - Lemmy.world

Hi folks, I got a heat pump installed at my home and I’m looking to better understand when/how it switches over to backup fuel in the winter. My unit is the LENNOX ELITE EL18XPV SERIES, which I found heating specs on here [https://ashp.neep.org/#!/product/109625/7/25000///0] It is installed in conjunction with a heating oil fired boiler and an aqua coil as the backup heat source. When it was installed, I asked, and the installer indicated that the heat pump will switch over to the boiler at about 37F. What I don’t fully understand though, is that this unit was billed as a variable speed/inverter, so it seems it should be able to run at lower temperatures than 37. The website above seems to indicate it should produce 31,800 BTU/h at 17F, so can I set the “switch-over” temperature of outside to be lower to use less oil?