Fridge to heat pump?

[jaybee]

Am I right in thinking that a heat pump is just a fridge in reverse as it were?

Could I not run my coil tube buried outside through an old fridge and take the heat generated?

[benjamindees]

Perhaps a freezer would be better.  You want to be able to make the coils colder than the outside temperature.  This is the reason heat pumps aren't used in really cold climates.