Lower Energy Bills with Low-Flow Pre-Rinse Spray Valves
By John Sustar, E Source Research Analyst -- Foodservice Equipment & Supplies, 5/1/2007 12:00:00 AM
Installing low-flow pre-rinse spray valves in the dishroom represents one of the easiest and most cost-effective methods of saving hot water in a commercial kitchen. Operators use low-flow spray valves, which discharge hot water at a rate no greater than 1.6 gallons per minute (gpm) at a water pressure of 60 pounds per square inch, to remove food scraps from utensils, pots, dishes, and pans before placing them in a dishwasher. Since January Jan. 1, 2006, all new pre-rinse valves sold have been low-flow, as required by the U.S. Energy Policy Act of 2005 (EPAct 2005). However, facilities using older, less less-efficient spray valves, with typical flow rates of 4 to 6 gpm, can realize considerable savings by switching to low-flow spray valves.
Pre-rinse sprayers consist of a squeeze lever, valve, nozzle, dish guard bumper and a locking handle that allows the sprayer to be locked in the “on” position which that can produce a great deal of wasted water. Unlike many other kitchen devices, these sprayers tend to be relatively inexpensive and operators can easily install or replace them. Pre-rinse valves typically last about five years. Improper installation or use, and poor water quality can shorten their life span.
Water heating in commercial kitchens accounts for nearly 10 percent of the total energy use. Installing low-flow sprayers can reduce the amount of hot water required to wash dishes in kitchens by 50 percent or more without compromising cleanliness or slowing down the dishwashing process. According to the Food Service Technology Center (FSTC) located in San Ramon, CACalif., substituting a low-flow spray valve for a valve flowing at 3 gpm for 2 two hours per day will save more than 43,000 gallons of water and $600-$700 annually. The FSTC offers a free online tool that can help calculate cost savings from installing a low-flow valve..
To find out more about how much energy savings are actually achieved in commercial kitchens, the California Urban Water Conservation Council (CUWCC) performed monitoring as part of its low-flow valve program. The program replaced more than 33,000 high-flow valves with low-flow models between 2002 and 2005 at no charge to participating establishments. The new valves reduced the average pre-rinse water-flow rate at those businesses from 3.35 to 1.11 gpm. A consultant metered a sample of the replacement valves to evaluate comprehensive water and energy savings. On average the valves saved 137 gallons per day, resulting in average gas savings of 0.92 therms per day for establishments with gas-fired water heaters; average electricity savings came to 20.9 kilowatt-hours per day for businesses with electric water heaters. These reductions in consumption have saved participating establishments anywhere from $500 to $1,000 per year. Funding for the program came from California public benefit funds and local water utilities. However, even without funding, the valves present an attractive payback for food-service businesses. At a cost of around $60 per low-flow valve, the payback period is less than two months. CUWCC has made additional information available online.
Based on the success of the CUWCC pre-rinse spray valve program, a second field measurement study was performed in the Regional Municipality of Waterloo, Ontario. The Waterloo pilot project involved replacing pre-rinse spray valves in ten 10 different facilities. The organization monitored the flow rate of the existing fixture, the flow rate of the replacement fixture, the supply pressures, and the duration of use. At the conclusion of the pilot, the results showed that each low-flow valve saved approximately 64 gallons of water per day. The total estimated savings for each valve over a 5-year lifetime was over $1,500, including water, wastewater, and energy costs.
Low-flow spray valves perform best with annual maintenance. Compounds in water can build up in the spray valve and lengthen the time to rinse dishes, thus reducing their cleaning effectiveness. For best performance, clean low-flow pre-rinse spray valves at least once a year. For severely clogged valves, it is more cost-effective in most applications to replace the valve with a new, low-flow model instead of attempting to restore the valve to its original condition.
To choose the best low-flow sprayer, consider one tested and approved by the American Society for Testing and Materials (ASTM). ASTM has developed a “Standard Test Method for Pre-Rinse Spray Valves” that includes testing the water consumption flow rate and the cleaning efficiency of pre-rinse spray valves. Selecting a pre-rinse spray valve that is approved by ASTM is the best way to ensure that the valve will reduce water consumption but still effectively clean dishes in a short period of time. The FSTC has listed pre-rinse spray valves that were tested and approved under the ASTM standards.
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