Food Service Technology Center · Performance of Rack Conveyor, Commercial Dish-washing Machines.1 Dishwashing machine perfor-mance is characterized by preheat and idle energy consumption

Food Service Technology Center

Hobart CL44E Dishwashing Machine Appliance Test Report FSTC Report # 501300938

Application of ASTM

Standard Test Methods F1920-11

December 2012

Prepared by: Denis Livchak Fisher-Nickel, Inc.

Prepared for: Pacific Gas & Electric Company

Customer Energy Efficiency Programs PO Box 770000

San Francisco, California 94177

Fisher-Nickel, Inc. All rights reserved. 2012

Hobart CL44E

Appliance Test Report

Food Service Technology Center Report # 501300938-R0 2

Food Service Technology Center Background

The information in this report is based on data generated at the PG&E Food Service Technology Center (FSTC). Dedicated to the advancement of

the foodservice industry, The FSTC has focused on the development of standard test methods for commercial foodservice equipment since 1987.

The primary component of the FSTC is a 10,000 square-foot appliance laboratory equipped with energy monitoring and data acquisition hardware,

60 linear feet of canopy exhaust hoods integrated with utility distribution systems, appliance setup and storage areas, and a state-of-the-art demon-

stration and training facility.

The FSTC Energy Efficiency for Foodservice Program is funded by California utility customers and administered by Pacific Gas & Electric Company

(PG&E) under the auspices of the California Public Utilities Commission. California consumers are not obligated to purchase any full service or other

service not funded by the program.

Policy on the Use of Food Service Technology Center Test Results and Other Related Information Fisher-Nickel, Inc. and the FSTC do not endorse particular products or services from any specific manufacturer or service provider.

The FSTC is strongly committed to testing foodservice equipment using the best available scientific techniques and instrumentation.

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endorse any of the equipment tested at the FSTC.

FSTC test results are made available to the general public through technical research reports and publications and are protected under U.S. and

international copyright laws.

In the event that FSTC data are to be reported, quoted, or referred to in any way in publications, papers, brochures, advertising, or any other pub-

licly available documents, the rules of copyright must be strictly followed, including written permission from Fisher-Nickel, Inc. in advance and proper

attribution to Fisher-Nickel, Inc. and the FSTC. In any such publication, sufficient text must be excerpted or quoted so as to give full and fair repre-

sentation of findings as reported in the original documentation from FSTC.

Disclaimer

Neither Fisher-Nickel, Inc. nor the FSTC nor any of its employees makes any warranty, expressed or implied, or assumes any legal liability of re-

sponsibility for the accuracy, completeness, or usefulness of any data, information, method, product or process disclosed in this document, or repre-

sents that its use will not infringe any privately-owned rights, including but not limited to, patents, trademarks, or copyrights.

Reference to specific products or manufacturers is not an endorsement of that product or manufacturer by Fisher-Nickel, Inc., the FSTC, or PG&E. In

no event will Fisher-Nickel, Inc. or PG&E be liable for any special, incidental, consequential, indirect, or similar damages, including but not limited to

lost profits, lost market share, lost savings, lost data, increased cost of production, or any other damages arising out of the use of the data or the

interpretation of the data presented in this report.

Retention of this consulting firm by PG&E to develop this report does not constitute endorsement by PG&E for any work performed other than that

specified in the scope of this project.

Legal Notice This report was prepared as a result of work sponsored by the California Public Utilities Commission (Commission). It does not necessarily represent

the views of the Commission, its employees, or the State of California. The Commission, the State of California, its employees, contractors, and

subcontractors make no warranty, express or implied, and assume no legal liability for the information in this report; nor does any party represent

that the use of this information will not infringe upon privately owned rights. This report has not been approved or disapproved by the Commission

nor has the Commission passed upon the accuracy or adequacy of the information in this report.

Revision History

Revision num. Date Description Author(s)

0 December 2012 Initial release Denis Livchak

Hobart CL44E



Contents

Page

Executive Summary ....................................................................................................................................... 5

Introduction .................................................................................................................................................... 6

Background .................................................................................................................................................. 6

Objectives .................................................................................................................................................... 6

Appliance Description .................................................................................................................................. 7

Methods and Results ..................................................................................................................................... 8

Setup and Instrumentation ........................................................................................................................... 8

Measured Energy and Water Pressure Test ................................................................................................ 9

Preheat and Idle Tests ................................................................................................................................. 9

Washing Tests ............................................................................................................................................. 10

Energy Cost Model ...................................................................................................................................... 12

References ..................................................................................................................................................... 14

Appendix A: Glossary of Terms ................................................................................................................... 15

Appendix B: Appliance Specifications ........................................................................................................ 16

Appliance Summary Report .......................................................................................................................... 20

Report Certification ....................................................................................................................................... 22

Hobart CL44E



Figures

Page

1 Hobart CL44E Conveyor Dishwashing Machine ....................................................................................... 5

2 Hobart CL44E Dishwashing Machine Ventilation Setup in the Lab ........................................................... 8

3 Hobart CL44E Dishwashing Machine Wash Tank Temperature Test Profile ............................................ 11

Tables

Page

1 Summary of Hobart CL44E Conveyor Dishwashing Machine Performance.................................................. 5

2 Hobart CL44E Appliance Specifications ........................................................................................................... 7

3 Testing Equipment Inventory ............................................................................................................................ 8

4 Input, Preheat, and Idle Test Results for the Hobart CL44e Dishwashing Machine ......................................... 10

5 Hobart CL44E Dishwashing Machine Washing Energy Rate and Cycle Rate Test Results ............................. 11

6 Hobart CL44E Conveyor Dishwasher Estimated Energy Consumption and Cost ............................................ 13

Hobart CL44E



Executive Summary

Conveyor dishwashing machines have become common appliances in medium to large commercial kitchens.

As one of the biggest consumers of hot water and electricity, conveyor-type dishwashing machines have be-

come a major contributor to the total restaurant energy usage.

The Hobart CL44E shown in Figure 1 is a 44 inch conveyor electric dishwashing machine with an internal

booster heater using a hot water supply. To determine dishwashing machine performance, FSTC engineers

used ASTM F1920-11 Standard Test Method for

Performance of Rack Conveyor, Commercial Dish-

washing Machines.1 Dishwashing machine perfor-

mance is characterized by preheat and idle energy

consumption rate, washing energy and water rate per

rack and heavy load cycle rate. Washing energy rate

and cycle rate was determined by washing racks of

ten plates in succession while maintaining the re-

quired minimum wash tank temperature. The Hobart

CL44E dishwashing machine achieved a washing

energy rate of 331 wh/rack while washing 60.6 racks

per hour with incoming hot water; the idle energy

rate was 1.39 kW. A summary of the test results is

presented in Table 1.

Table 1: Summary of Hobart CL44E Conveyor Dishwashing Machine Performance

Rated Input (kW) 46.6

Measured Maximum Energy Rate (kW) 46.1

Fill and Preheat Time (min) 9.42

Preheat Energy Consumption (kWh) 2.36

Idle Energy Rate (kW) 1.39

Washing and Booster Energy Rate (kW) 20.6

Washing and Booster Energy Rate (Wh/rack) 331

1 American Society for Testing and Materials. 2011. Standard Test Method for Performance Rack Conveyor, Commercial Dishwash-

ing Machines. ASTM Designation F1920-11, in Annual Book of ASTM Standards, West Conshohocken, PA.

Figure 1: Hobart CL44E Conveyor Dishwashing Machine

Hobart CL44E



Washing Water Consumption (gal/rack) 0.70

Heavy-Load Cycle Rate (racks/hr) 60.6

Introduction

Background

Rack conveyor dishwashing machines have become a necessity in today’s non-quick service, high-production

commercial kitchens. These machines are able to wash and sanitize various types of wares and utensils, con-

sistently at a high volume, while having a small footprint relative to flight type dishwashing machines. Dish-

washing machine contribution to the total restaurant energy consumption is significant. A built –in electric

booster heater is often needed to preheat large volumes of water to help reach required sanitation temperatures.

The ASTM designation ASTM F1920-11 Standard Test Method for Performance of Rack Conveyor, Com-

mercial Dishwashing Machines characterizes dishwashing machine performance by evaluating its energy and

water consumption, heavy load washing cycle rate and idle energy rate. ASTM appliance performance can be

used to estimate an appliance’s contribution to the energy consumption of an end-user’s kitchen.

The glossary in Appendix A is provided so that the reader has a reference to the terms used in this report.

Objectives

The objective of this report is to examine the operation and performance of the Hobart CL44E conveyor-type

dishwashing machine under the controlled conditions of the ASTM designation F1920-11 Standard Test

Method for Performance of Rack Conveyor, Commercial Dishwashing Machines. The scope of this testing is

as follows:

1. Verify that the appliance is operating at the manufacturers’ rated energy input.

2. Verify that the appliance is operating at the NSF’s rated water consumption rate.

3. Determine the time and energy required to fill and preheat the dishwashing machine from 140F

water temperature to minimal operational wash tank temperature and until the tank heater ele-

ments cycle off.

4. Characterize the dishwashing machine’s idle energy use.

5. Determine the dishwashing machine’s washing energy rate under a specified ASTM dish loading

scenario.

6. Determine the dishwashing machine’s heavy load cycle rate for the ASTM dish loading scenario

while maintaining minimum wash tank temperature.

Hobart CL44E



Appliance Description

The Hobart CL44E is an electric 44 inch long conveyor dishwashing machine with a rated total input rate of

46.6 kW and a wash tank capacity of 23 gallons. The dishwashing machine features a built in electric booster

heater designed for a 70F rise rated at 30.0 kW and an electric resistance heating element inside the wash tank

rated at 15 kW. The dishwasher and the booster heater require separate 240 volt electrical wiring. The 2hp

motor circulates the water during the wash cycle through two nozzle sections located above and below the belt.

The conveyor belt operating at 5.6 feet per minute is powered by a 1/6 hp motor which is automatically trig-

gered the entrance of the dishrack into the wash cavity. The front panel of the dishwashing machine has digital

readout indicating the temperature of the wash tank and the rinse water. There is also a mechanical gauge in-

dicating the rinse water pressure.

Table 2: Hobart CL44E Appliance Specifications

Appliance Conveyor-type Dishwashing Machine

Manufacturer Hobart

Model CL44E

Serial Number 85-1070669

Generic Appliance Type Conveyor Dishwashing Machine

Total Rated Input

Booster Input

Minimum Rated Wash Pressure

Specified Wash Tank Volume

46.6 kW

30.0 kW

20 psi

23.0 gal

Operating Voltage

Minimum Rated Wash Temperature

Minimum Rinse Temperature

240 V

160 F

180 F

Controls On/Off; Start/Stop; Conveyor Dwell

Construction Stainless steel

Washing Cavity Dimensions (W x D x H) 22" x 44" x 20.5”

External Dimensions (W x D x H) 31.25" x 43.5" x 68.5"

Hobart CL44E



Methods and Results

Setup and Instrumentation

FSTC researchers installed the dishwashing machine into a large conditioned lab space. The dishwashing ma-

chine was placed on the floor with a two feet rear clearance to allow for electrical connections. The rack inlet

and outlet of the dishwashing machine were ducted and connected to a vent fan to exhaust the steam of the

machine outside the lab (Figure 2). The louvers for the inlet and outlet of the machine were balanced to ex-

haust 200 cfm on the entrance and 400cfm on the discharge

side. The floor-drain was connected to the machine by 1 –

½” PVC pipe. 3 foot end tables provided by the manufactur-

er were attached to both ends of the dishwashing machine to

load and unload the dishwasher.

The Hobart CL44E dishwashing machine was installed in

accordance with the manufacturer’s instructions in a condi-

tioned test space. The room was maintained at an ambient

condition of 75 ± 5°F during testing. Supply air was provid-

ed at very low velocity in order not to disturb the machine’s

airflow. Dishwashing machine energy and water consump-

tion was measured with equipment listed in Table 3.

Table 3: Testing Equipment Inventory

Description / ID Manufacturer Model Measurement

Range

Resolu-

tion

Calibration Date Next Cali-

bration

electric meter / ALB 201 Shark FTB4705 0.2 A – 50.0 A 7.50 Wh 11/12/10 11/12/11

electric meter / ALA 105 Shark FTB4705 0.4 A – 100.0 A 15.00 Wh 11/12/10 11/12/11

Water Meter / SN: 150606

Omega 4605 0 – 13 GPM 0.0066 gal (Verified Internally)

8/24/2011

NA

Submerged Type K thermocouples were used to measure the incoming water supply, wash tank and rinse wa-

ter temperatures on the Hobart CL44E dishwashing machine. Wash tank, pump energy and control electric

energy was measured using a three-phase current transducer meter. The booster heater energy was measured

using a separate three-phase current transducer meter. The dishwashing machine’s water consumption was

measured using a calibrated mechanical paddle wheel style water meter with a digital pulse output. The energy

Figure 2: Hobart CL44E Dishwashing Machine Ven-tilation Setup in the Lab

Hobart CL44E



transducers, water meter and thermocouple probes were connected to a computerized data acquisition unit that

recorded data at 5 second intervals.

Measured Energy and Water Pressure Test

Rated energy input rate is the maximum or peak rate at which the dishwashing machine consumes energy as

specified on the manufacturer’s nameplate. Measured energy input rate is the maximum or peak rate of energy

consumption, which is recorded during a period when the heating elements are fully energized in the booster

heater and the tank heater (i.e. the rinse cycle). Prior to testing, the energy input rate was determined by meas-

uring the energy consumed from the time the booster heater first began operating until the elements first cycled

off. This procedure ensured that the dishwashing machine was operating within its specified parameters. The

measured energy input rate of the dishwashing machine was 19.50 kW and the input rate of the booster heater

was 26.55 kW. This energy consumption was within 17% from the full nameplate rating of the dishwashing

machine and 12% from the booster heater nameplate rating. The rinse pressure of a rack conveyor dishwash-

ing machine was adjusted to 20 psi. Table 3 summarizes the results from the energy input test.

Preheat and Idle Tests

These tests show how the dishwashing machine uses energy when it is not washing dishes, but ready to wash.

The preheat test was conducted at the beginning of a test day after the dishwashing machine was stabilized at

room temperature overnight and filled with 140°F water. The preheat test also includes the time it takes for the

wash tank to fill with water. The tank heater elements do not turn on until fully submerged. The preheat test

recorded the time and energy required for the machine to reach minimum wash tank temperature of 160°F and

complete its cycle. The tank temperature was monitored next to the factory tank temperature probe.

Data recording began when the dishwashing machine was first turned on. The test results include any time de-

lay before the powering of the elements. The tank was filled with 20.5 gallons of 140°F hot water over a period

of 3.42 minutes and the tank heater elements energized 1.67 minutes into the fill after 9.4 gallons of water

were in the tank. The booster heater consumed 945 Wh of electrical energy between minute 1.67 and 3.92 of

the tank fill. During the preheat test, the dishwashing machine reached the minimum tank temperature of

160°F in 7.00 minutes, while consuming 2565 Wh of electrical energy. It took 9.42 minutes for the dishwasher

heater elements to cycle off when the tank temperature reached 174°F, consuming a total of 3300 Wh. Idle

energy rate represents the energy required to maintain the manufacturer’s set point temperature, which is

equivalent to the appliance’s standby losses. After the dishwashing machine was preheated, it was allowed to

stabilize for a minimum of 1 hour. Time and energy consumption were monitored for an additional three-hour

period while maintaining an operational average temperature of 169°F inside the wash tank. The idle energy

Hobart CL44E



rate while maintaining a ready-to-wash state was 1.23 kW for the tank heaters and 0.17 kW for the booster

heater.

Table 4: Input, Preheat, and Idle Test Results for the Hobart CL44E Dishwashing Machine

Rated Dishwasher Energy Input Rate (kW) 15+1.5+0.12

Measured Dishwasher Energy Input Rate (kW) 19.50

Percentage Difference (%) 17.3

Rated Booster Heater Energy Input Rate (kW) 30.0

Measured Booster Heater Energy Input Rate (kW) 26.6

Percentage Difference (%) 11.5

Preheat Duration (min) 9.42

Preheat Tank Heater Energy Consumption (Wh) 2,355

Preheat Booster Heater Energy Consumption (Wh) 945

Total Electric Preheat Energy Consumption (Wh) 3,300

Preheat Temperature at location (°F) 174

Idle Tank Heater Energy Rate (kW) 1.23

Idle Booster Heater Energy Rate (kW) 0.17

Total Electric Idle Energy Rate (kW) 1.39

Average Idle Temperature at location (°F) 169

Washing Tests

Standard dish racks weighing 4.1 lbs were used for this test and were loaded with 10 plates, evenly spaced,

averaging 1.35 lbs each. The dishwasher was stabilized by running empty racks for a period of 5 minutes, and

then was allowed to recover until the elements cycled off at 174°F tank temperature. The washing test consist-

ed of washing five racks loaded with 10 dishes back to back allowing the dishwasher to recover after each set

of five racks and tank elements cycled off. The next set of 5 racks was loaded onto the machine as soon as the

tank heater elements cycled off. A total of 6 sets of 5 racks were washed and the first set was discarded for

stabilization resulting in 25 racks (5 sets of 5 racks) of dishes used for the washing test. The tank temperature

was maintained above 160±1°F throughout the entire test. Rinse temperature was held above 180°F during

each rinse cycle. Figure 3 shows the wash tank temperature profile during the entire test.

Hobart CL44E



Figure 3: Hobart CL44E Dishwashing Machine Wash Tank Temperature Test Profile

Total dishwasher energy, booster heater energy and water consumption was recorded for each test run. The

Hobart CL44E dishwashing machine demonstrated an average washing energy rate of 15.22 kW throughout

the entire test. The booster heater average energy rate was 14.61 kW due to the fact that it operated at full

power only during the rinse cycle of the machine, which took up a small fraction of the total test time. The

heavy load cycle rate for the machine was 60.6 racks per hour. The Hobart CL44E dishwashing machine re-

covered to 174°F before the elements cycled off. Gas water heating energy was calculated for hot water supply

machines to bring up the water volume used for the washing test from 60°F to 140°F at 65% water heater effi-

ciency. The wash test results are summarized in Table 6.

Table 6: Hobart CL44E Dishwashing Machine Washing Energy Rate and Cycle Rate Test Results

Rinse Pressure (psi) 20

Washing Energy Rate (kW) 15.22

Booster Energy Rate (kW) 14.61

Washing Tank Energy Rate (Wh/rack) 251

Booster Heater Energy Rate (Wh/rack) 80

Gas Water Heating Energy (Btu/rack) 715

Total Washing Energy Rate (Wh/rack) 331

Washing Water Consumption (gal/rack) 0.70

Average Supply Water Temperature (F) 143

Average Rinse Water Temperature (F) 189

Minimum Tank Temperature (F) 159

Heavy Load Cycle Rate (racks/hr) 60.6

155.0

160.0

165.0

170.0

175.0

180.0

0 5 10 15 20 25 30 35 40

Tan

k Te

mp

era

ture

(F)

Test Time (min)

5 minute stabilization First Stabilization Set 5 test run sets

Hobart CL44E



Energy Cost Model

The test results can be used to estimate the annual energy consumption for the Hobart CL44E conveyor type

dishwashing machine in a real-world operation. A simple cost model was developed to calculate the relation-

ship between the various cost components (e.g., preheat, idle, water heating and washing costs) and the annual

operating cost, using the ASTM test data (see Equations 1 and 2 below). Any chemical costs such as detergent

are not included in these calculations. Water heating costs are estimated assuming 65% gas water heater effi-

ciency and 80F temperature rise using Equation 3.

Eelec,daily = Eelec,h +Eelec, i +np ´Eelec, p (Equation 1)

helecq ,h elec,

PC

W =E

60PC

W =E , ielec,

pponielec

tntq

Eelec,daily = W

PC´ qelec, h + qelec, i ´ ton -

W

PC-

np ´ tp

60

æ

èç

ö

ø÷+np ´Eelec, p (Equation 2)

65.0/08*GPR*W*8.29 =E daily heating, water gas (Equation 3)

Where:

Eelec,daily = Daily energy consumption

W = Number of racks washed per day

PC = Heavy Load Cycle Rate

qelec,h = Washing energy rate

qelec,i = Idle energy rate

ton = Total time the appliance is on per day

np = Number of preheats per day

tp = Duration of preheat

Eelec,p = Preheat energy

Eelec,h = Heavy-load cooking energy

Eelec,i = Idle energy

GPR = Gallons Per Rack

The model is based on a large full service restaurant, washing 400 racks of dishes over a 14-hour day, one

preheat per day, 364 days per year (excluding one holiday per year). HVAC and ventilation costs are not in-

Hobart CL44E



cluded in this model. Table 7 summarizes the annual electric and gas water heating energy consumption and

associated energy cost for the dishwashing machine.

Table 7: Hobart CL44E Conveyor Dishwasher Estimated Energy Consumption and Cost

Preheat Energy (kWh/day) 3.30

Idle Energy (kWh/day) 10.07

Washing Energy (kWh/day) 132.4

Water Heating Energy (kBtu/day) 285.7

Annual Electric Energy (kWh/year) 53,060

Annual Gas Energy (therms/year) 1,040

Annual Cost ($/year)a 8,999

a Dishwashing energy costs are based on $0.15/kWh and $1.00/therm

Hobart CL44E



References

1. American Society for Testing and Materials, 2011. Standard Test Method for Performance of Rack Con-

veyor, Commercial Dishwashing Machines. ASTM Designation F1920-11, in Annual Book of ASTM

Standards, West Conshohocken, PA.

Hobart CL44E



Appendix A: Glossary of Terms

CFM

Volumetric flow rate - Cubic Feet per Minute

Convection (kW or Btu/h)

The rate of thermal energy transfer between air in motion and a

bounding surface when the two are at different temperatures.

Cooking Energy (Btu, kWh)

The total energy consumed by an appliance as it is used to

cook a food product under specified test conditions.

Cooking Energy Rate (kW, Btu/h, or kBtu/h)

Average rate of energy consumption, in hours, during a cook-

ing test.

Cycle Rate (racks/h)

Maximum rate, racks per hour, at which a dishwasher can

wash and sanitize in groups of 5 racks while maintaining a

minimum tank temperature above 160F.

FPM

Velocity – Feet Per Minute

HVAC

Heating Ventilation and Air Conditioning.

Set Point (°F)

Targeted temperature set by appliance controls.

Test Method

A definitive procedure for the identification, measurement and

evaluation of one or more qualities, characteristics, or proper-

ties of a material, product system, or service that produces a

test result.

Typical Day

A sample day of average appliance usage based on observa-

tions and/or operator interviews. Used to develop an energy

cost model for an appliance.

Uncertainty

Measure of systematic and precision errors in specified instru-

mentation, or measure of repeatability of a reported test result.

Idle Temperature (°F)

The temperature of the tank (either selected by the appliance

operator or specified for a controlled test) that is maintained by

the appliance under an idle condition.

Idle Energy Rate (kW or Btu/h)

The rate of energy consumption by an appliance per hour

while it is “holding” or maintaining a stabilized operating

condition or temperature.

Measured Energy Input Rate (kW, Btu/h, or kBtu/h)

The peak rate at which an appliance will consume energy,

typically measured during preheat (i.e. the period of operation

when all burners or elements are “on”). Does not include

energy used for appliance controls.

Plug Load

The power requirement of an appliance, usually measured at

the plug.

Preheat Energy (kWh, Wh or Btu)

The total amount of energy consumed by an appliance during

the preheat period (from ambient temperature to the specified

thermostat set point).

Preheat Energy Rate (°F/min)

The rate, in degrees Fahrenheit per minute, at which the ap-

pliance increases temperature during preheat.

Preheat Time (min)

The time required for an appliance to heat from the ambient

room temperature (75 ± 5°F) to a specified (and calibrated)

operating temperature or thermostat set point.

Production Capacity (lb/h)

Maximum rate, in pounds per hour, at which an appliance can

bring a specified product to a specified “washed” condition.

Radiation (kW or Btu/h)

The rate of thermal energy emitted by a surface dependent on

its temperature and emissivity.

Rated Energy Input Rate (kW, W or Btu/h)

Maximum or peak rate at which an appliance consumes ener-

gy, as rated by manufacturer and specified on the nameplate.

.

Hobart CL44E



Appendix B: Appliance Specifications

Hobart CL44E




Hobart CL44E




Hobart CL44E




Hobart CL44E



Appliance Summary Report:

Hobart CL44E



Appliance Summary Report:

Food Service Technology Center Report # 501300938-R0

22

Documents

Food Service Technology Center · Performance of Rack Conveyor, Commercial Dish-washing Machines.1 Dishwashing machine perfor-mance is characterized by preheat and idle energy consumption