Technically, -any- heat pump is more than 100% efficient if the metric is heat delivered vs power expended.
...it's kinda the point.
Heat pumps tap an outside source of heat.
In the case of the miraculous Minnesota heater, a guy noticed that hydraulic fluid heated up when it was circulated. He made a fancy radiator and circulated hydraulic fluid through it, then used a fan or blower to remove the heat. Measuring the airflow (CFM) and both input and output temperatures allows one to compute the amount of energy which heated the known volume of air. Comparing this to the electricity used to drive the pumps and the fan allowed one to compute the efficiency.
IF the temperatures were measured in kelvin vs. centigrade. Going from, say, 20C to 30C yields results appreciably different than going from 283k to 293k.
Coming up next: using lasers to separate hydrogen and oxygen in water to run a fuel cell which will power the lasers and produce water to refill the fuel tank in a closed loop, with enough energy left over to power a car. (Another invention that got some press a number of years back. )