What a Heat Pump Is Actually Doing at Minus Five

A heat pump does not make heat. It moves heat from outdoor air into your house, and how well it does that job changes with the outdoor temperature. That change follows a curve, and the curve is the one number that actually decides your heating bill. The coefficient of performance curve on a named Mitsubishi cold-climate unit runs from a COP of 4.0 on a 47-degree afternoon down to 1.8 at minus 5 degrees Fahrenheit. This video shows what happens to your electric bill at every point on that curve, what the backup strip heat costs when it kicks in, what the defrost cycle actually does and what it wastes, what changed with cold-climate compressor technology, and exactly how to look up the curve for your own unit for free using the model number on your outdoor unit and the manufacturer's submittal sheet. More on household systems and building physics every week:    / @themeasuredhouseyt   Sources referenced: Mitsubishi Hyper-Heating INVERTER (H2i) submittal data (MSZ-FS09NA / MUZ-FS09NA), NEEP Cold Climate Air Source Heat Pump Specification Version 4.0, MacFarland demand defrost field data via Energy Vanguard, EIA national average electricity rates. NEEP product list: ashp.neep.org Nothing in this video is a specific recommendation for your house.