Heat pumps are having a moment in Colorado, but do they really work in the bitter cold? Yes.

There was a touch of anxiety in the home of Jon and Rachel Rea as a bomb cyclone, with its plummeting subzero temperatures, approached Colorado in December, for the couple no longer had a gas-fired furnace in their basement.

They had replaced the furnace three months earlier with a heat pump and now that new gizmo was going to face a major test. The heat pump gathers the slivers of heat lingering in the air even on a cold day, but with temperatures plunging toward 20 below zero would there be any heat left to capture?