ENERGY EFFICIENCY How-to at home: selecting a heat pump

If your old HVAC system is no longer doing its job, it may be time to upgrade to a new, more efficient system. Air-source heat pumps are a great option that can help you save money and energy.

Heat pumps provide highly efficient heat and cooling, but there are different types available with different features and levels of performance. Which one is right for you? Here are tips to help you make the best choice.

Air source

These heat pumps are the most commonly installed. They work well in moderate climates with mild winters, though advances in technology make them a good option for other regions, as well.

A heat pump has a compressor and two coils — one inside and one outside. In winter, liquid refrigerant in the outdoor coil absorbs heat from the air which turns it into a gas. The indoor coil releases heat from the gas as it condenses back into liquid. In summer, this process is reversed as the heat pump moves warm inside air to the outdoors. Heat pumps move heat, rather than create it.

Levels of performance

Heat pumps are available at different levels of performance — single-stage, two-stage and variable speed. Single-stage units intermittently fill your home with cold or warm air and turn themselves off when the desired temperature is reached. Two-stage units operate at full capacity when you need it, and at a lower level (or turn off) when you don’t.

Variable-speed units blow a low level, continuous stream of conditioned air into your living space to maintain the desired indoor temperature. Whenever higher capacity is needed, it smoothly ramps up to whatever level is required. Variable-speed units rarely turn off completely.

Benefits of multiple speeds

Two-stage and variable-speed heat pumps offer a number of advantages over single-stage units:

• Energy savings. Running motors at slower speed saves a lot of energy. Speeds above 75% of capacity are typically only needed on the hottest or coldest days of the year.

• Better humidity control. Moving air more slowly over cold coils removes more water vapor from the air. Lower indoor humidity allows you to bump up the thermostat in the summer and still feel comfortable.

• Improved indoor air quality. Circulating the air through filters for a longer period results in improved indoor air quality.

• Quieter operation. Running at lower speeds is much quieter than running at full capacity.

• Consistent comfort. A softer start at lower speed avoids sending out a blast of unconditioned air from the ducts every time the unit turns on.

Split ductless

Split ductless heat pumps, also called mini-splits, operate similar to air-source models except that these systems don’t require ductwork, so they’re good options for single-room additions or homes without ducts.

Ductless systems include at least two units, a compressor and condenser outside, and one to four air handlers inside. The quiet, indoor units are often installed high on a wall or on the ceiling. The system is operated by a remote control and circulates refrigerant through tubing that connects the indoor and outdoor units.

Though installing this type of system with multiple indoor units can be costly initially, the lack of ductwork reduces energy losses and provides temperature control of individual rooms. That will save you money on future energy bills.

Upgrading or adding a heat pump is a job for a professional. Contact a qualified HVAC technician who can determine and install the right unit for your home.