Heating and Cooling

Water Heating

In the Commercial and Institutional sector, natural gas provides 74.5 per cent of the energy used in water heating. Petroleum-based sources provide 19.4 per cent and electricity 6.1 per cent.

Common systems in Canada

Storage water tanks are the most common type of water heater in Canada and store water in a single tank. The energy source used can be natural gas, electricity or fuel oil.

Using an electric element or gas burner to heat water on demand, tankless water heaters are usually situated close to where the water will be used and generally have lower capacity than storage tank water heaters.

Integrated space/water heating systems employ a single burner, boiler and vent to heat water for both space heating and hot water uses. The hot water circulates through a heat exchanger and the resulting hot air is blown through the building as with a conventional heating system.

Heat pump water heaters transfer heat from the air, or from the earth or groundwater, to water in a tank. They do not generate heat, and are not effective at temperatures below 8°C (46°F).

Solar water heaters use energy from the sun to heat water in a solar collector. The water is then transferred to a storage tank, where it is either heated further by a conventional storage tank heater or passed through a heat exchanger to heat water for home use.

Heat recovery water pre-heaters are heat exchangers that recover heat from used hot water as it goes down the drain. The recovered energy is used to preheat water in a conventional storage tank heater.

New water heating technologies

There are several new technologies that improve energy efficiency in water heating systems, including high-efficiency water heaters and electronic ignition.

High-efficiency water heaters have better insulation and flue controls to prevent heat loss, more efficient heat exchangers and special valves that prevent hot water from entering the piping system when it isn’t needed.

Electronic ignition on gas water heaters saves natural gas by eliminating pilot lights.

Direct contact water heaters are gaining popularity. With this type of heater, cold water is sprayed from the top of a cylinder and comes into direct contact with combustion gases injected from the bottom. Different designs disperse the water in different ways to maximize its surface area and thus heat the water more efficiently.