[ovi256]

Heat pump output temp is lower than a furnace's. Thus, it needs to move more air to inject the same heating power.

In Europe, where the traditional working fluid is usually water in water radiators, this has been a big issue in popularizing heat pumps. Radiators sized right for hot water from electric or gas furnaces were undersized for heat pumps and their lower output temp. This required expensive replacing of the water network and radiators.

Heat pumps in new builds are popular for heated floors, which are great.