An air source heat pump system will provide efficient heating and cooling for your home—one and a half to three times more heat energy than the electrical energy it consumes. Although useable in nearly all parts of the United States, air source heat pumps are best for warm climates. New systems with gas heating as backup are able to overcome this problem; a new Cold Climate Heat Pump and a Reverse Cycle Chiller also show promise for operating efficiently at below-freezing temperatures.
A heat pump’s refrigeration system consists of compressor and two coils made of copper tuning—one indoors and one outside. These are surrounded by aluminium fins to aid heat transfer. In the heating mode liquid refrigerant extracts heat from the outside coils and air and moves it inside as it evaporates into a gas. The indoor coils transfer heat from the refrigerant as it condenses back into a liquid. A reversing valve near the compressor can change the direction of the refrigerant flow for cooling as well as for defrosting the outdoor coils in winter.
In cooling mode, an air-source heat pump evaporates a refrigerant in the indoor coil; as the liquid evaporates it pulls heat from the air in the house. After the gas is compressed it passes into the outdoor coil and condenses releasing heat to the outside air. The pressure changes caused by the compressor and the expansion valve allow the gas to condense at a high temperature outside and evaporate at a lower temperature indoors.
In heating mode, an air-source heat pump evaporates a refrigerant in the outdoor coil; as the liquid evaporates it pulls heat from the outside air. After the gas is compressed it passes into the indoor coil and condenses releasing heat to the inside of the house. The pressure changes caused by the compressor and the expansion valve allow the gas to evaporate at a low temperature outside and condense at a higher temperature indoors.
When outdoor temperatures fall below 40°F, a less-efficient panel of electric resistance coils—similar to those in your toaster—kicks in to provide indoor heating. This is why air-source heat pumps aren’t always very efficient for heating in cold climates. Some units now have gas-fired backup furnaces instead of electric resistance coils allowing them to operate more efficiently. The efficiency and performance of today’s air-source heat pumps is one and a half to two times greater than those available 30 years ago. This improvement in efficiency has resulted from technical advances and options such as these:
- Thermostatic expansion valves for more precise control of the refrigerant flow to the indoor coil
- Variable speed blowers which are more efficient and can compensate for some of the adverse effects of restricted ducts, dirty filters, and dirty coils
- Improved coil design
- Improved electric motor and two-speed compressor designs
- Copper tubing, grooved inside to increase surface area.
Most central heat pumps are split-systems—they each have one coil indoors and one outdoors. Supply and return ducts connect to a central fan which is located indoors.
Some heat pumps are packaged systems. These usually have both coils and the fan outdoors. Heated or cooled air is delivered to the interior from ductwork that protrudes through a wall or roof.
GeoForce Energy provides residential heating and air conditioning services in Vancouver, West Vancouver, Squamish, Whistler, Tsawwessen, Burnaby, Richmond, Ladner, New Westminster, Surrey, Delta, White Rock, Cloverdale, Langley, Walnut Grove, Aldergrove, Port Moody, Port Coquitlam, Abbotsford and Metro Vancouver. Please call us today at 604.897.3411 for a quote or connect with us by filling out our short form here.