We are about to have a Mitsubishi ZUBA (Canadian) heat pump installed. This unit puts out a steady 38,000 BTUH over much of the temperature range we will see.

My question is - Does the COP improve when the inverter slows the compressor down to match the required load? The numbers below show how the COP varies with temperature at the maximum output.

BTW, the part of our home unit will serve has a design heat load of about 42k BTUH at -25C (-13F) design temperature.

Code:
Outdoor deg F         BTUH     INPUT KW        COP    BTUH needed
50                   39710      3.521          3.3     7500
40                   38000      3.23           3.4     12000
30                   38000      4.684          2.4     17000
20                   38000      5.491          2.0     22000
10                   38000      5.911          1.9     27000
0                    35720      6.04           1.8     32000