Hot Water

Your building's service hot water (SHW) system generates, stores, distributes, and dispenses hot water. Multiple components and the overall design of the system affect the amount of energy consumed. SHW can account for significant energy consumption. Here are some ECOs applicable to commercial buildings.

Reduce Hot Water Consumption

By installing flow reduction devices, you can effectively reduce the consumption of hot water. These devices include flow restricting orifices, which are installed in the line; aerators that reduce flows and mix water with air; and, self-closing hot water faucets.

Reduce the Temperature Setting

The temperature setting of most SHW systems range from 120°F to 150°F. For dishwashing and sterilization, the required delivery temperature ranges to 180°F. In many cases, the highest temperature required for one use is supplied to all taps throughout the system. Lowering the SHW temperature setting saves energy because a lower temperature results in reduced system losses. For example, when water temperature is reduced from 180°F to 125°F, heat losses experienced in uninsulated piping in a 68°F room are cut in half. A significant temperature reduction also can extend the life of a glass-lined storage tank. Set the temperature control to the lowest point that will accommodate the majority of uses. By lowering the temperature to 105°F, for example, chances are you will be able to accommodate the majority of hot water needs. For uses that require higher temperatures, a small booster heater can be installed near the point of use. The booster heater raises this temperature to the needs of the device served. An economic analysis probably will show that the savings obtained by reducing the central system temperature will quickly pay back the cost of installing and operating the booster heaters. If the building has a laundry room, using lower temperature wash/rinse cycles may reduce water temperature requirements. If a space heating boiler is used to provide hot water, lower the thermostat setting to 105°F. If the SHW system is the only summer load on the space heating boiler, consider installing a separate water heater for summer SHW heating. The savings achieved by avoiding summertime losses usually results in a rapid payback for the separate system. Be aware of all applicable building health and food handling codes. The SHW temperature specified in these codes must be met. Very often they can be adhered to through application of booster heaters.

Improve Service Water Heating Maintenance

While SHW systems require relatively little maintenance, you can save energy and extend the life of many of its components by following a few tips.

• Inspect piping and tanks frequently. Repair or replace loose or hanging insulation. If insulation is water-damaged, locate the source of the leak, repair it, and install new insulation.
• Repair all leaking faucets.
• Flush the water heater during seasonal maintenance of the heating system.
• Repack circulating pump packing glands to reduce hot water leakage.
• In the case of oil- or gas-fired water heaters, routinely check for smoky exhaust, high stack temperatures, and high CO levels. Adjust the air-to-fuel ratio to optimum levels. (Information about proper settings can be obtained from local utilities and suppliers.)
• Make sure that boiler water covers immersion tankless SHW coils.
 
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