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Water Heater Efficiency Requirements
Energy EfficiencyEnergy efficiency means using your building's individual components to do the same job as less efficient components for less money over the long-term.Storage Water HeaterCommercial water heaters are major energy consumers in many commercial facilities, accounting for about 11% of the total energy load on average. A hospitality facility may use up to 40% of its energy for heating water. In evaluating the water heating needs of your facility and the potential for improving energy efficiency, consider the facility's needs carefully, including time of use, amount of water, temperature range and flow rates.
Technology OptionsCommercial water heaters are available in storage, instantaneous, indirect (unfired hot water storage tank), heat pump and tankless coil (heat recovery) configurations.Energy use varies by type: 75 to 500 kBtu/hr input for gas, 105 to 500 kBtu/hr for oil, and greater than 12 kW input for electric. Commercial water heaters include hot-water supply boilers as well. These are simply boilers configured to supply potable hot water rather than space heating. Emerging Technology Condensing gas water heaters are increasingly popular, especially given the recent trend of rising gas prices. Commercial heat pump water heaters are making progress as well. Instantaneous Water HeaterCash rebates are available to HVAC contractors or owners of gas cooling equipment in the commercial and residential market who replace existing gas units with qualifying gas air conditioning products installed in the Southern California Gas Company service territory.Solar Water HeatingSolar water-heating systems use collectors, generally mounted on a south-facing roof, to heat either water or a nontoxic antifreeze that is circulated from the collector to the water storage tanks. The heated water is then stored in a water tank similar to one used in a conventional gas or electric water-heating system.Collectors heat water either "passively" or "actively." Passive solar water-heating systems use natural convection or water pressure to circulate water through a solar collector to a storage tank. They have no electric components that could break, a feature that generally makes them more reliable, easier to maintain, and possibly longer lasting than active systems. An active system uses an electric pump to circulate water or a nontoxic antifreeze through the system. Active systems are usually more expensive than passive systems, but they are also more efficient. Active systems are easier to retrofit than passive systems because their storage tanks do not need to be installed above or close to the collectors. Also, the moving water in the system will not freeze in cold climates. But because these systems use electricity, they will not function in a power outage. That's why many active systems are now combined with a small solar-electric panel to power the pump. The amount of hot water a solar water heater produces depends on the type and size of the system, the amount of sun available at the site, proper installation, and the tilt angle and orientation of the collectors. Energy Sources for Water HeatersElectric water heaters efficiencies do not vary significantly from 98% thermal efficiency. Another measure of energy efficiency for these units is the standby loss, expressed in percentage of loss per hour. Typical values range from 0.5% to 2.0%. The lower the value, the more efficient the electric water heater.Heat-pump water heaters are a good option for electrical applications. Commercial heat pump water heaters are rated using a coefficient of performance (COP). COPs range from 1.5 to 3.5. The higher the COP, the better the energy performance. Even though an electric water heater's thermal efficiency is high at 98%, gas- or oil-fired units may cost less to operate since fossil fuel prices are significantly lower than electricity prices. When considering water-heating equipment, analyze the cost-effectiveness of each possible solution to determine the best type of unit for your application. Indirect water heaters may also be referred to as unfired hot water storage tanks. Since these devices are heated by an external source, their efficiency is determined by how well they are insulated. For the best efficiency, look for low heat-loss values. A typical maximum value is 6.5 Btu/h per square feet of tank area, or a minimum R-value of 12.5.
Numerous commercial water heater manufacturers make energy saving water heaters
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