Is it difficult to move a heat pump unit to a location about 15 feet away? Is it just a matter of moving the unit and extending the connections, or is there something more complicated about it?

You have to pump the refrigerant out of the system or pump the refrigerant into the condenser and recover what is left to a separate tank. Also disconnect the electric both high and low voltage.

Then you have to extend the electric to the new location for both high and low voltage. The refrigerant lines will also have to be extended and brazed into place. You might want to add a drier to the system since it has been opened. Then the new lines will have to be leak checked. A vacuum will have to be pulled on the open part of the system then the refrigerant released from the condenser. Once that is done the unit will have to have the pressures adjusted by adding or removing refrigerant to the proper pressures to obtain the proper subcooling or superheat for operation.

There is a lot of work to be performed just to move the unit and a professional is required because of the refrigerant and brazing skills required. You also have to be EPA certified to work with the refrigerant/freon.