# Page 107 - WaterSense at Work

October 2012
4-13
4.3
Combination Ovens
Equation 4-3. Water Use of Combination Oven (gallons per year)
=Water Use Rate of Combination Oven x Daily Use Time x Days of
Facility Operation
Where:
••
Water Use Rate of Combination Oven (gallons per hour)
••
Daily Use Time (hours per day)
••
Days of Facility Operation (days per year)
Water Use After Replacement
To estimate the water use of a replacement combination oven, use Equation 4-3,
substituting the replacement combination oven’s hourly water use. Connectionless
combination ovens can use 15 gallons per hour or less.
Water Savings
To calculate the water savings that can be achieved from replacing an existing com-
bination oven, identify the following and use Equation 4-4:
••
Current water use as calculated using Equation 4-3.
••
Water use after replacement as calculated using Equation 4-3.
Equation 4-4. Water Savings FromCombination Oven Replacement (gallons per year)
= Current Water Use of Combination Oven –Water Use of Combination
Oven After Replacement
Where:
••
Current Water Use of Combination Oven (gallons per year)
••
Water Use of Combination Oven After Replacement (gallons per year)
Payback
To calculate the simple payback associated with the water savings from replacing
an existing combination oven, consider the equipment and installation cost of the
replacement combination oven, the water savings as calculated using Equation 4-4,
and the facility-specific cost of water and wastewater. A combination oven can cost
approximately \$15,000.
27
By switching to a connectionless combination oven, facilities also save a significant
amount of energy by reducing the water use and steam generation associated with
27
Harris, Richard. EBMUD. March 5, 2008. “Turning up the Heat on Commercial Kitchen Water Savings.” Slide 26.