02/01/2026
Zero degrees F or C may sound like there is no heat in the air, but that's just a number humans have assigned to it. There is heat in the air all the way down to 0⁰K (-459.67⁰F/-273.15)
Sadly I have seen too many people that work in the HVAC field tell homeowners, after it gets below 32 turn it to emergency heat, or in the teens or single digits. Heat pumps will continue pumping heat into your home, as it gets colder it does lose capacity but still way more efficient than electric heat.
If you have a 2 ton heat pump (24,000 BTU) with 10kw auxiliary heat (around 34,000 BTU), even when the capacity is reduced to half (12,000 BTU) it's still providing heat, keeping the auxiliary heat off longer, when it does kick on makes it kick off sooner. When they run side by side you are getting both 12,000 BTU and 34,000 BTU for a total of 46,000 BTU, but saving as much money as possible in the process!
Hope this helps!