Heat pumps 101: trading heat with the environment

By Ken Kellar
Staff Writer

Time marches on, and so too does technology, but new tech means new and more efficient ways of keeping your home the perfect temperature.

Not future tech, but still new and gaining prominence in the province, are heat pumps. A heat pump is an almost all-weather temperature solution designed to use the stable ambient temperature of the planet to move hot and cold air into your home, depending on the season.

Heat pumps rely on having a source of thermal energy that the main unit will use, as well as a sink, which is the destination for that thermal energy, according to the Government of Canada’s official site. In Canada, two main sources for heat pumps are generally used, which are air-source and ground-source systems. Air-source heat pumps take heat from the air outside the home during the heating season and expels hot air back outside during the warmer months. The other, ground-source systems, work in generally the same fashion, only they exchange temperatures with the earth or groundwater under the home.

Ground-source systems can also function in a number of different fashions. There are ground-source systems that only provide heating to the house or a terminal system like a radiator or radiant floor system, while other ground-source systems can provide cooling via an active or passive function.

Both sourced systems need to have the sink in order to function, which can come in a few different forms. According to the government, the two most commonly used sinks are an in-home air heater, usually a centrally-ducted system or wall-mounted ductless unit, or by heating water in a terminal system.

The benefits to a heat pump system lie in their efficiency. A furnace or boiler heats an area by adding heat to the air via the combustion of a fuel, but some of the energy generated from combustion is lost and so isn’t used to provide heat. A heat pump, on the other hand, uses electrical energy to transfer thermal energy between two locations, which allows for higher efficiency, and often even efficiencies over 100 per cent, which means that more thermal energy is produced than the amount of electrical energy needed to pump it.

However, the efficiency of the heat pump depends on the temperatures of both the source and the sink, which means that the higher the difference in temperatures between the two locations, the harder the system will have to work to move the thermal energy, and the less efficient it becomes. A properly-sized heat pump is therefore crucial in making sure your system runs as efficiently as possible.

Because winters in northern Ontario can fall well below what is considered “ideal” for a home’s interior, there have historically been some concerns about how well a heat pump can service a home in the region. While systems continue to get more efficient as the technology improves, a home can also include a supplementary heat source for when the temperatures drop too low. In order to keep a home as efficiently heated as possible, one suggestion for a supplementary system is an electric baseboard heater system, thus ensuring the home continues to be kept warm in the winter months via an electrically-powered system at the highest possible efficiency.

When considering a heat pump for your home, it’s important to note that ground-sourced systems require a network of pipes to be buried below the earth to house the liquids that provide the transfer of thermal energy between source and sink. Therefore, a ground-sourced system may not be within every homeowner’s budget, or there may not be room in a municipal area to install the pipes. Homeowners interested in a heat pump system should seek out and consult with an expert who can install the system they are interested in, as well as knows the municipal regulations that may prohibit or interfere with larger installation projects. As a heat pump system often supplies a greater volume of airflow to a home at a lower temperature than a furnace system, it’s also recommended that homeowners have their existing ducting examined, as excess airflow can lead to noise issues or increased fan energy use.