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Heat Pumps

A heat pump is a machine or device that moves heat from one location (the 'source') to another location (the 'sink' or 'heat sink') using mechanical work. Most heat pump technology moves heat from a low temperature heat source to a higher temperature heat sink. Common examples are food refrigerators and freezers, air conditioners and reversible-cycle heat pumps for providing thermal comfort.

 

Heat pumps can either supply or remove heat from your home by circulating a refrigerant between two heat-exchange coils.

 

To supply heat, low-pressure liquid refrigerant is evaporated by absorbing low-grade heat from the air, water, or ground.

 

When the evaporated refrigerant is mechanically compressed, the temperature of the gas increases.

 

Heat is released when this pressurized gas condenses back into a liquid.

 

Heat pumps can cool a home by reversing this process.

 

Air source heat pumps absorb natural warmth from the air outside and gently distribute it throughout your home. They are the most efficient type of home heating system and also offer the added benefits of central air conditioning and summer dehumidification.

 

Benefits:

A heat pump provides year-round climate control, producing even, comfortable heat in winter and air conditioning in summer. It dehumidifies too, reducing mould and excess moisture.  A heat pump also filters the air to reduce irritants that could aggravate breathing problems. And it’s a non-combustible heat source, so it uses no flames, no fuel and produces no fumes.
Heat pumps are as affordable as any other heating system. For every unit of energy used, they can produce over three units of heat. This efficiency makes them cost-effective. In fact, you can heat and cool your home for about the same annual cost as other heat-only systems.

 

How a heat pump works:

The system works on a simple principle. The heat pump absorbs heat from the outside air in winter and circulates it in your home through ductwork. In the summer it works in reverse, removing heat and humidity from your home and releasing it outside.

 

The heat pump meets the full heating requirements of the house at an outside temperature of -7oC or warmer. This is commonly referred to as the balance point. A back-up heating source provides supplementary heat at temperatures below the balance point.

 

Types of heat pumps:

The back-up heating source depends on whether the unit is an add-on or all-electric. Add-on heat pumps are designed to be used in conjunction with another heating system such as an oil or electric furnace. An all-electric air source heat pump comes equipped with its own electric back-up built in.

 

If the heat pump is all-electric, the electric back-up source automatically provides supplementary heat as required, maximizing efficiency and saving money. A homeowner can see even greater savings by combining a heat pump with electric thermal storage and taking advantage of Nova Scotia Power’s time-of-day rate.

If the heat pump is an add-on, it will shut off if the outside temperature drops below the balance point, and only the furnace will heat the home. Adding a heat pump to a forced-air furnace will optimize the efficiency of the heating system.

 

Installation, service and maintenance:

A properly installed heat pump will maximize the efficiency of your system and provide years of heating and cooling comfort. Nova Scotia Power can recommend certified installers and quality heat pumps that are backed by comprehensive warranties. Once installed, arranging for a qualified firm to service the heat pump will keep it operating at peak efficiency and extend the life of the components. Annual service plans are available from heat pump contractors for approximately the same cost as furnace service plans.

 

For a detailed look at this topic, download the NS Department of Energy's Introduction to Home Heating brochure.

 

If you have additional information relevant to this page please send it to info@energyconsultant.ca noting that it will be reviewed for content prior to any posting.

 

We acknowledge the NS Department of Energy and Nova Scotia Power for contributing information to this page. Their websites are  www.gov.ns.ca/energy/AbsPage.aspx and www.nspower.ca.