Buying Guide: What is a heat pump and how does it work?

Having an energy-efficient heating and cooling system is crucial to keeping you comfortable. And for some, a heat pump might be the way to go. 

Get ready to buy - before it breaks

Home heating systems have a certain lifespan – furnaces last approximately 15-20 years, and boilers may last a few years longer. If you’re considering a heat pump for your home, keep in mind it’s a bit more complex than simply replacing of existing equipment. It may involve modifying duct work, possibly changing your electrical service, finding space for an outdoor condensing unit, and in some cases, running refrigeration lines or wiring into different areas of your home.

Not sure how to decide if a heat pump is right for your home? First, you need to understand the issues and ask the right questions.

What is a heat pump?

A heat pump is a machine that moves heat from one place to another, typically using an electromechanical compressor. That means it can be used to heat up and cool down a given living space. Refrigerators and air conditioners operate using the same principle.

An air-source heat pump uses outdoor air as a heat source and a heat sink, while a ground-source heat pump uses the thermal mass of the earth to extract heat and move it into your home or to take heat out of your house to cool it down.

Heat pump technology has been around for a long time and it’s constantly being improved upon. Heat pumps for space heating and cooling are gaining in popularity for homeowners.

Comparing efficiency and costs

Typically, furnaces and boilers create heat through the combustion of natural gas, oil or propane, while heat pumps run on electricity. This difference can make it difficult to compare long-term operating and fuel costs and your return on investment.

With all the different units and rates, an independent rating system such as the ENERGY STAR^® Most Efficient  list can provide some projected numbers to help you make your choice.

Your HVAC contractor should also have some tools available to help you understand the life cycle operating costs. That information can be used with the ENERGY STAR^® list to help make a well-informed decision on the best choice for your home.

Ducted vs. ductless

Air-source heat pumps can be ducted or ductless. A ducted heat pump works in a similar way to a central furnace, connected to ductwork in the home and controlled by a central thermostat. A ductless unit has a heat exchanger and blower in a self-contained package and can be mounted on your wall or floor. These systems can have multiple heads, serving one or many areas in your home.

Many people choose the ductless version when they want to have flexibility in controlling heating and cooling in multiple areas or in a home with no ductwork. Some may choose to install this type of system on the top floor of a house, or in a home extension that needs a bit of supplemental heating and cooling.

Start with the right contractor

Replacing your home's heating, ventilation and air conditioning (HVAC) system is a big undertaking and requires expertise. The first step is to find a qualified, licensed contractor. They can help you make the best purchase decision for your home and your needs. In Ontario, HVAC contractors must be licensed and registered with the Technical Standards and Safety Authority.

It’s important to get separate written estimates from at least three different contractors. Each contractor should assess the size, construction and layout of your home and undertake a heat loss calculation when providing you with options. They should determine if the ductwork is adequate to meet the air flow needs of your new equipment. The estimate should include information on the recommended equipment, plus efficiency and warranty details. You should also ask your contractor to include the costs of removing and disposing of your old furnace correctly. After your equipment is installed, make sure you get it inspected.

How does an air-source heat pump save energy?

Air-source heat pumps use the refrigeration cycle to move heat into and out of your home instead of burning fuel to create heat. Cold climate air-source heat pumps are specially designed to extract heat from outdoor air at temperatures as low as -25°C. As the outside air temperature drops, however, so does the heat pump's ability to pull heat out of the air and the efficiency of these units can decline. Even in a cold snap, however, air-source heat pumps are still more efficient than electrical heating systems and can be more cost-effective than oil and propane heaters.

Hybrid solution?

Many homes have both a furnace (or boiler) and air conditioner to meet their heating and cooling needs. There’s a growing trend to update this common coupling by replacing the air conditioner with an air-source heat pump that does the job of air conditioning in the summer and may also be a more efficient, less expensive option for most of the heating season.

This solution can have a lower life cycle cost to a homeowner, and also provide a more environmentally friendly solution. If you plan to take advantage of a rebate or incentive to help pay for the heat pump, check the eligibility requirements as some new installations may require a complete replacement of the existing heating and cooling system.

Your local contractor or designer will have to work out the controls integration with you, but by using the right products that are installed correctly, it’s no more complex than your existing thermostat set-up.