Multi-zone and single-zone ASHP
A single-zone system ASHP is meant for a single room with one outdoor condenser that has capacity to heat or cool a single room. The multi-zone installations can have two or more indoor units all of which connected to a single outdoor unit.
Air-to-water ASHP
These draw heat from the air outside and transfer this to water that can be used for radiant heating or to produce hot water for the house. However air source heat pumps cannot produce water at a very high temperature. Unlike boilers that can provide water at 85 degrees, an ASHP can go up to 55 degrees. If you try to wrench out a higher temperature it will make the unit work harder. This will have an impact on the utility bill and also influence its efficiency and coefficient.
Air-to-air heat pumps
These draw heat from the air and transfer it to the forced air system in the house.
Modern AHSP are quite advanced than the past models. These units are integrated with thermostatic expansion valves for a better control of the refrigerant flow to the indoor coil. They have variable speed blowers that can push air aptly through gunk filled ducts and dirty filters and coils. The design of the coil, motor and compressor has been streamlined to increase its efficiency. The copper tubing is grooved inside to increase surface area.
Tax benefits:
If you buy an Energy Star certified ASHP, you will get a Federal tax credit of $300. This is to encourage people to increase their dependency on renewable sources of energy. But the units should met following requirements-