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Water Heating

The amount of hot water used in a building varies greatly depending on the building operations. For instance, use in a commercial office building may be limited to hand-washing, janitorial cleaning and minor kitchen use; an industrial facility may use water in their manufacturing processes; and a multi-family property will use hot water for cooking, dishwashing, laundering, and bathing.

Regardless of the type of building operation, reducing the demand for hot water should be the first priority. Not only will you save on your energy expense, but on your water bill as well.

Tankless water heaters, also known as on-demand heaters or instantaneous, heat water only when it is needed and do not require a storage tank. Typically, commercial tankless water heaters are gas-fired. Electric models tend to be more expensive to operate, particularly during peak times.

By heating water 1 only when it is needed an Energy Star qualified gas tankless water heater can cut heating expenses by as much as 30 percent. As an added benefit, water consumption is reduced since the users no longer have to wait for warm water to reach remote faucets.

Multiple units can be combined in a system of water heaters for larger applications such as commercial kitchens, apartment buildings, etc.

Gas condensing water heaters enable the fuel to transfer nearly all of its heat to the water. Flue gasses are recaptured and used to reduce heat and energy waste. This produces a 95% efficiency or greater and may lead to energy savings up to 20%.

High efficiency gas storage water heaters are among the most common types of water heaters, ranging in size from 20 to 100 gallons. Storage-type water heaters are common, but they are inefficient due to high standby losses. Heat loss occurs through the flue pipe and walls of the tank.

Boilers are typically part of a larger system that is used to produce heat. A boiler may use natural gas, oil or wood pellets to heat water. The heat from the burning fuel is transferred through a heat exchanger and into the water. Depending on the purpose of the boiler, it may be used simply to heat the water, or to increase the temperature to the point that the water becomes steam. The type of fuel, and the temperature the water is heated to, depends on the need of the commercial operations.

Heat-pump water heaters generally use half the energy of electric resistance water heaters. Additionally, they may provide a cooling/dehumidification benefit, depending on the application. Refer to the Swimming Pool improvement sheet.

Solar water heaters or solar domestic hot water systems are generally used by businesses with large hot water heating needs such as laundries, hospitals, hotels/motels and apartment buildings. However, a small residential system may make sense for limited usage. Their cost-effectiveness is greater when replacing electric water heating systems.

The two basic components are solar collectors, which are mounted on the roof and oriented to provide optimum solar exposure, and an insulated tank. Active systems contain pumps for circulating the collection fluid (water or propylene glycol), while passive systems do not. Commercial applications generally use the active closed-loop systems.

Tips for lowering your water heating energy:

  • Lower the temperature of your water heater.
  • Insulate older water heaters. Check your manufacturer’s specifications to make sure you won’t void the warrantee by adding insulation.
  • Insulate hot water pipes.
  • If you have an electric water heater install a timer.
1 U.S. Department of Energy & EnergyStar
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