4 ms·

What is the principle at work behind a heat pump?

• ZeroGravitas 7y ago
  It's a fridge running backwards. Gasses expand soaking up heat, then you compress them and it ejects the heat. Then you repeat the cycle. You dump the heat outside if you're cooling (fridge or AC) or inside if you're heating. The slightly unintuitive bit is that you can still extract heat even from something that would feel "cold" to a human as long as there's enough of it. Making a big volume slightly colder can make a small volume much warmer (or vice versa).