An air-source heat pump provides an efficient and renewable way to heat and cool your home. The use of a heat pump results in reduced consumption of energy, significant financial savings, and a cleaner environment.
Because of the versatility of air-source heat pumps, they provide an ideal heating and cooling solution for almost any building.
(Did you know that) installing an air-source heat pump could reduce your home’s GHGs by up to 6 tonnes in one year!
How They Work
Air-source heat pumps transfer heat by circulating a liquid/gaseous substance called a refrigerant through a cycle of evaporation and condensation. The refrigerant absorbs heat from the outside air and evaporates. It then passes through a compressor, which increases its temperature and upgrades the heat; heat that is released inside your home. In the summer, this process is reversed to provide cooling; heat is drawn from the air inside your home and transferred outside. The result is a comfortable, more evenly distributed heat during the winter and cooler temperatures during the summer making an air-source heat pump an efficient solution for all seasons.
Air-source heat pumps work in combination with a “backup” furnace – electric, gas or oil. The heat pump supplies approximately 90% of your home’s annual heating while the backup furnace provides the remaining 10%. The backup furnace maintains the desired indoor air temperature during the coldest weather, and also during the heat pump’s “defrost” cycle. The backup furnace will also switch on to raise your home’s air temperature quickly, if required.
(Did you know that) air at – 5 degrees C can supply 75% of your heating needs!
Where You Save
Incorporating an air-source heat pump into the construction or renovation of your home will result in immediate savings in your energy costs. When you run a heat pump, you will use less fossil fuel but somewhat more electricity; except when replacing electric heating, in which case you’ll definitely use less electricity with a heat pump.
The following figures show the annual cost savings you can expect when incorporating an air-source heat pump retro-fit into your home. The calculations are based on a typical 2,500 square foot home, built to today’s standards on the West Coast.
In addition to reduced energy costs, air-source heat pumps significantly reduce the emission of greenhouse gases (GHGs), making them the most environmentally friendly choice for heating and cooling.
(Did you know that) installing an air-source heat pump could save you up to $1,500 in one year!
What You Need to Know
Terms and Definitions:
HSPF: Heating Seasonal Performance Factor. The HSPF rating measures heating efficiency; the higher the rating, the more efficient it is. Use the HSPF to compare the performance of different models, and look for units with an HSPF rating of at least 7.7.
SEER: Seasonal Energy Efficiency Ratio. The SEER rating measures cooling efficiency; the higher the rating, the more efficient it is. Look for ENERGY STAR rated heat pumps with a minimum SEER rating of 14.
Sizing your heat pump:
To size the heat pump, most contractors will use their experience in estimating your home’s heat loss plus a rule of thumb of one nominal ton of capacity per 600 to 800 square feet of floor area. One ton of heating capacity is equivalent to 12,000 Btu/hr, or 3.5 kilowatts. Most heat pumps range in size from 2-½ to 4 tons.
The most accurate sizing method that accounts for the specific features of your house is called a heat loss calculation. A Certified Energy Advisor can perform the heat loss calculation, and qualify you for a federal ecoEnergy retrofit grant.
The capacity of the existing ductwork to accommodate greater air flow is also crucial in proper sizing. Heat pumps require 400 to 450 cubic feet per minute of air flow is per ton of heat pump capacity. Some extra duct branches are often added, and the size of blower motor will generally need to be increased. Your contractor should calculate the required duct area with a duct size calculator and the blower speed needed to properly match the heat pump.
- If you are also installing a new electric backup furnace, you may have to upgrade the electrical service to your house. This usually costs around $2,500.
- Heat pumps operate more continuously than conventional furnaces and due to the increased air flow, some additional duct noise may result. Air at the register will also tend to be cooler than a conventional furnace.
- Choose R-410a refrigerant for its lower environmental impact. Unlike R-22 Freon refrigerant, R-410a does not deplete the earth’s ozone layer. Equipment using R-22 Freon will be phased out of production by 2010.
- Variable speed drive (VSD) blower motors are strongly recommended to improve the efficiency and lower electrical consumption.
- Older ductwork is often missing a return air grille in the basement. Have your contractor install a new return air grille close to the floor to provide proper heating in the basement.
- Where none exists, have your contractor install a fresh air duct to the return air plenum. This helps introduce fresh outdoor air into the house whenever the blower is running.
- Over-sizing a heat pump can result in a shorter life. It can also cause the compressor to operate inefficiently and be extra noisy. Over-sizing should be avoided.
Questions to consider when buying an air-source heat pump:
What experience does your contractor have? Is the contractor a licensed refrigeration mechanic? Ask if they can provide references.
What is the manufacturer’s warranty for the system? What does it include? Typical warranties are 10 years for the compressor, 5 years for other parts, and 1 year for labour.
How does the initial cost of an air-source heat pump compare to traditional heating and cooling systems? And how quickly do energy savings contribute to offset the initial investment? While most air-source heat pumps are more expensive than traditional furnaces – between $6000 – $10,000 – the time to recoup its cost in energy savings can be as little as 3 years. The reduced energy consumption also results in fewer greenhouse gas emissions, which is friendlier for the environment.
What are the HSPF and SEER ratings for the air-source heat pump? The higher the rating, the more efficient the system.
What is the noise rating of the system? Check product specifications or ask your contractor for the decibel rating of the outdoor unit. Try to choose an air-source heat pump with a rating of 70 decibels or lower.
Questions to consider when buying an air-source heat pump retro-fit:
Have you had an air flow and duct capacity calculation performed? Existing duct work may require modification if a newly installed air-source heat pump is to work efficiently.
A Quality First™ trained heating technician is certified to size ducting.
How energy efficient is your home? You may be losing heat due to poor insulation or air leakage through cracks and holes. A Certified Energy Advisor can determine the heat loss and advise on the most suitable energy upgrades.
How old is your existing furnace? If your existing furnace is older than 15 years, consider upgrading to a new backup furnace along with the heat pump.
Where should the outdoor unit be placed? Be sure to allow for enough space around, and above, the heat pump for air to easily enter and exit the unit. The unit should also be placed where noise can escape up and away from neighbouring houses, usually in the backyard.
The federal ecoENERGY program offers up to $400 for qualified heat pump installations.