Like all heating and cooling systems, proper maintenance is key to efficient operation. The difference between the energy consumption of a well-maintained heat pump and a severely neglected one ranges from 10–25%.

Clean or change filters once a month or as needed, and maintain the system according to manufacturer’s instructions. Dirty filters, coils, and fans reduce airflow through the system. Reduced airflow decreases system performance and can damage your system’s compressor. Clean outdoor coils whenever they appear dirty; occasionally, turn off power to the fan and clean it; remove vegetation and clutter from around the outdoor unit. Clean the supply and return registers within your home, and straighten their fins if bent.

You should also have a professional technician service your heat pump at least every year. The technician can do the following:

1. Inspect ducts, filters, blower, and indoor coil for dirt and other obstructions
2. Diagnose and seal duct leakage
3. Verify adequate airflow by measurement
4. Verify correct refrigerant charge by measurement
5. Check for refrigerant leaks
6. Inspect electric terminals, and if necessary, clean and tighten connections, and apply nonconductive coating
7. Lubricate motors, and inspect belts for tightness and wear
8. Verify correct electric control, making sure that heating is locked out when the thermostat calls for cooling and vice versa
9. Verify correct thermostat operation.

The air then comes in through the heat pump and is made into heat so you have can have warm water

Geology

Factors such as the composition and properties of your soil and rock
(which can affect heat transfer rates) require consideration when
designing a ground loop. For example, soil with good heat transfer
properties requires less piping to gather a certain amount of heat than
soil with poor heat transfer properties. The amount of soil available
contributes to system design as well — system suppliers in areas with
extensive hard rock or soil too shallow to trench may install vertical
ground loops instead of horizontal loops.

Hydrology

Ground or surface water availability also plays a part in deciding
what type of ground loop to use. Depending on factors such as depth,
volume, and water quality, bodies of surface water can be used as a
source of water for an open-loop system, or as a repository for coils
of piping in a closed-loop system. Ground water can also be used as a
source for open-loop systems, provided the water quality is suitable
and all ground water discharge regulations are met.

Before you purchase an open-loop system, you will want to be sure
your system supplier/installer has fully investigated your site’s
hydrology, so you can avoid potential problems such as aquifer
depletion and groundwater contamination. Antifreeze fluids circulated
through closed-loop systems generally pose little to no environmental
hazard.

Land Availability

The amount and layout of your land, your landscaping, and the
location of underground utilities or sprinkler systems also contribute
to your system design. Horizontal ground loops (generally the most
economical) are typically used for newly constructed buildings with
sufficient land. Vertical installations or more compact horizontal
“Slinky™” installations are often used for existing buildings because
they minimize the disturbance to the landscape.

How They Work

Heat pump water heaters use electricity to move heat from one place to another instead of generating heat directly. Therefore, they can be two to three times more energy efficient than conventional electric resistance water heaters. To move the heat, heat pumps work like a refrigerator in reverse.

While a refrigerator pulls heat from inside a box and dumps it into the surrounding room, a stand-alone air-source heat pump water heater pulls heat from the surrounding air and dumps it—at a higher temperature—into a tank to heat water. You can purchase a stand-alone heat pump water heating system as an integrated unit with a built-in water storage tank and back-up resistance heating elements. You can also retrofit a heat pump to work with an existing conventional storage water heater. They require installation in locations that remain in the 40º–90ºF (4.4º–32.2ºC) range year-round and provide at least 1,000 cubic feet (28.3 cubic meters) of air space around the water heater. Cool exhaust air can be exhausted to the room or outdoors. Install them in a space with excess heat, such as a furnace room. Heat pump water heaters will not operate efficiently in a cold space. They tend to cool the spaces they are in. You can also install an air-source heat pump system that combines heating, cooling, and water heating. These combination systems pull their heat indoors from the outdoor air in the winter and from the indoor air in the summer. Because they remove heat from the air, any type of air-source heat pump system works more efficiently in a warm climate.

Continuing series on heat pumps and water heaters

Heat pumps are the most efficient form of electric heating in moderate climates, providing three times more heating than the equivalent amount of energy they consume in electricity. There are three types of heat pumps: air-to-air, water source, and ground source.

They collect heat from the air, water, or ground outside your home and concentrate it for use inside. Heat pumps do double duty as a central air conditioner. They can also cool your home by collecting the heat inside your house and effectively pumping it outside. A heat pump can trim the amount of electricity you use for heating by as much as 30% to 40%.

via the U.S. Department of Energy