# Page 128 - WaterSense at Work

4-34
October 2012
4.7
Dipper Wells
Water Use After Replacement With an ENERGY STAR Qualified Dishwasher
To estimate the water use after replacing an existing dipper well with an ENERGY
STAR qualified commercial undercounter dishwasher, identify the following informa-
tion and use Equation 4-15:
••
Water use per rack washed. A high-temperature, ENERGY STAR qualified commer-
cial undercounter dishwasher uses 1.0 gallons per rack or less. A low-temperature
model uses 1.7 gallons per rack or less.
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••
Average estimate of racks washed per day.
••
Days of facility operation per year.
Equation 4-15. Water Use of an ENERGY STAR Qualified Commercial,
Undercounter Dishwasher (gallons per year)
=Water Use per Rack x RacksWashed per Day x Days of Facility Operation
Where:
••
Water Use per Rack (gallons per rack)
••
Racks Washed per Day (racks per day)
••
Days of Facility Operation (days per year)
Water Savings
To calculate the water savings that can be achieved from replacing an existing dipper
well with an ENERGY STAR qualified commercial undercounter dishwasher, identify
the following information and use Equation 4-13:
••
Current water use as calculated using Equation 4-12.
••
Water use after replacement as calculated using Equation 4-15.
Payback
To calculate the simple payback from the water savings associated with replacing
an existing dipper well with an ENERGY STAR qualified commercial undercounter
dishwasher, consider the equipment and installation cost of the new dishwasher, the
water savings as calculated in Equation 4-13, and the facility-specific cost of water
and wastewater. Installing a new ENERGY STAR qualified commercial undercounter
dishwasher can cost approximately \$6,000.
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The facility should also consider the energy impact of replacing the dipper well with
an ENERGY STAR qualified dishwasher. The dishwasher might use less hot water than
the dipper well, but it also uses energy to run cleaning cycles.
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EPA and DOE’s ENERGY STAR. Commercial Dishwashers Key Product Criteria.
.
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EPA and DOE’s ENERGY STAR. Life Cycle Cost Estimate for 1 ENERGY STAR Qualified Commercial Dishwasher(s).
.