Testing And Reports





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TESTING AND REPORTS

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We have included excerpts from performance studies and engineering / evaluation reports, and believe that they are consistent with the reports’ findings and conclusions. Full copies of these reports may be made available to requesting parties on a case by case basis.

1. Energy Comparison Study, February 2, 1998
Materials Performance, Inc. (formerly Bradley Consulting Group)

"Comparison of Tankless Water Heaters Instantaneous Water Heater
and a Standard Electric 40 Gallon Storage Tank

by Steven W. Bradley
Materials Performance, Inc.
(formerly Bradley Consulting Group)
1501 FM 2818 Suite 208
College Station, TX 77840

PREFACE

This report presents the results of a utility study conducted for Tankless Water Heaters by the laboratories of Bradley Consulting Group in College Station, Texas. According to national energy standards, the average household hot water usage is 64.3 gallons per day in six primary draws.

Households of 4 or more will commonly use more than this amount. These tests represent a high volume consumption comparison of two different hot water heating systems. Note that this testing is not designed to provide a calculation of actual or even average cost as this will vary based on usage, inlet water temperature, storage location of heater and periods between hot water draws.

The testing was initiated to compare the percent difference of power consumption under the same conditions for each heater system.

INTRODUCTION

This utility study was initiated to compare the performance of the 28 kW Tankless Water Heaters instantaneous water heater with a standard 40 gallon electric water heater. This type of information is important to consumers who seek to both increase the availability of continuous hot water with a reduction in cost. This report will cover tests that were performed over a period of three months under simulated real-world conditions

Testing Protocol

Our chosen test regimen was to simulate service in a real household where draws are both concentrated at certain times of the day and then intermittent during other periods. Two potential service conditions were considered. The first was a water heater setting of 120 °F for both systems as recommended by the service manuals. The second condition, which is often found in households where hot water supply is exhausted, is a raised temperature setting of the 40 gallon tank to 135 °F. It was unnecessary to raise the Tankless Water Heaters system to a higher temperature as it is able to provide continuous hot water

Table 6: Average Test Cycle Values for 40 Gallon Tank at 135 °F

Cycle	Average Energy Used kW	Average Outflow GPM	Average Flow in Cold GPM	Average Flow in Hot GPM	Average Outflow Temp °F
Shower Test	2.88	3.0	2.8	0.2	100.5
Dishwasher Test	1.73	1.5	0.0	1.5	133.2
Wash. Machine Test	4.523	4.0	0.0	4.0	124.65
Standby Usage	0.71	0.0	0.0	0.0	133.2
Total Usage	9.84 kW	125.5 Gal	67.20 Gal	58.3 Gal	130.4 Hot

Table 7: Average Test Cycle Values for Tankless Water Heater

Cycle	Average Energy Used kW	Average Outflow GPM	Average Flow in Cold GPM	Average Flow in Hot GPM	Average Outflow Temp °F
Shower Test	2.916	3.0	1.9	1.1	100.5
Dishwasher Test	0.961	1.5	0.0	1.5	119.3
Wash. Machine Test	2.828	4.0	0.0	4.0	119.8
Standby Usage	0.29	0.0	0.0	0.0	119.7
Total Usage	6.99 kW	122.5 Gal	45.6 Gal	76.9 Gal	-

The following observations may be made regarding the data. The first cycle of the 40 gallon tank requires the least power consumption, as the tank has had plenty of time to replenish and is near the set point temperature. As each cycle is run, the power consumption increases as the water temperature in the 40 gallon tank decreases. This is also seen by the increasing amount of hot water flow required from the 40 gallon tank to maintain the 100 °F outflow temperature on the shower test. The tank heater will continue to heat for several minutes after completion of testing as it brings the water back to set point.

The Tankless Water Heaters system requires a higher consumption during the first cycle as the unit body itself is being heated with the water. In subsequent cycles, a decreasing amount of heat is required because the initial temperature at the beginning of the cycle is higher. The overall consumption of hot water from the Tankless Water Heaters system is lower as the tankless heater maintains set point temperature and requires the same mixture of hot and cold water for the shower test…

It is commonly held that many homeowners operate their water heaters at a higher temperature setting than 120 °F. Consultation with consumers confirmed that they will often set water heaters at 130 – 140 °F. The continuous hot water is an advantage of the in line heating system. It does not tempt homeowners or builders to set water temperatures at a set point that could cause scalding. Table 8 shows even higher amount of energy savings possible if 40 gallon tank settings are higher.

Table 8: Monthly Usage Comparison at 135 °F

	Days in use	Tankless Water Heaters monthly kW usage	40 Gallon monthly kW usage
Showers	30	87.48	86.4
Dishwasher	30	28.82	51.96
Washing Machine	16	45.25	72.4
Standby	30	8.70	21.3
Total		170.24	232.06
Percent Savings		26.6

It appears from these tests that the Tankless Water Heaters System in-line heater offers considerable power consumption savings with the benefit of continuous hot water availability. Situations involving high amounts of standby would increase the savings of an in line heater over a standby heater. In addition, larger volume uses appear to be more efficient with the Tankless Water Heaters system. Further testing is being initiated to consider heat and water losses due to piping."

Bradley Consultation is located in College Station, Texas. It specializes in consulting and testing in the area of materials performance. [Bradley Consulting is now known as Material Performance, Inc.

2. Evaluation of Tankless Water Heaters, Executive Summary
TVA (Tennessee Valley Authority)

Tankless Water Heaters Instantaneous Water Heater Monitoring Evaluation

Project Background and Executive Summary

Residential water heating represents a significant portion of TVA’s total electric sales. Historically, electricity has been the choice for water heating. However, where available, natural gas has been gaining market share and replacing conventional water heating systems. New residential water heating technologies are being continually evaluated to support TVA in defining more competitive positions against natural gas regarding operating costs the customer. The Residential and Small Commercial Marketing (RSCM) staff requested that Technology Advancements conduct an evaluation of the tankless water heating system.

Overall project results indicate that the Tankless Water Heaters system operates as the manufacturer claims. It maintained water temperatures under all operational flow conditions excepts when the flow rate exceeded the design capacity for the unit. The system power input emulates the instantaneous hot water demand for the residence. This will simplify modeling for the systems for overall power system impact as typical residential hot water demand profiles for the valley can be used.

Last July, preliminary results of the system operation were presented in a seminar at the American Society of Heating, Refrigeration and Air-Conditioning Engineers annual meeting in Boston. A copy of the slides for this presentation are included in Attachment 4. The full project report was delayed waiting for the manufacturer to develop and test the new solid state controller. This was delivered, installed, and tested and found to be satisfactory in September.

Project Description

Microtherm Incorporated of Conroe [now of Houston], Texas, is the manufacturer of the Tankless water heater. They installed one of their systems, Model RA-28, at a residence in Chattanooga, Tennessee.

The tankless water heater is an instantaneous electric water heater with the following features claimed by the manufacturer. Additional information is included as Attachment 1 to this document.

Molded nylon water heating chambers.
Solid state controls for uniform supply water temperatures.
Dual safety backup controls.
Power ratings from 11kW to 28 kW (a 28 kW unit was monitored).

Table 1 identifies the different Tankless Water Heaters models, their ratings, and power requirements.

Tankless Water Heaters Instantaneous Water Heater Monitoring Evaluation

Table 1. Tankless Water Heater Models and Capacities

UNIT	kW	Amperage	Btu's	Temp Rise @ 2.0 gpm	Temp Rise @ 3.0 gpm	Breakers Required
RA-11	30	87.48	86.4	86.4	86.4	86.4
RA-14	30	28.82	51.96	51.96	51.96	51.96
RA-22	16	45.25	72.4	72.4	72.4	72.4
RA-28	30	8.70	21.3	21.3	21.3	21.3

* All two-pole 240volts AC w/Grounded Neutral

** Above ambient temperature

Other claims by Tankless Water Heaters when compared to conventional water heaters include:

Increased Reliability – Solid state controls avoid overheating (provide longer element life), eliminate flow switch failures, eliminate minimum flow & pressure requirements, and the unit has a nylon resin molded tank.
Uniform water temperature – the system controls maintain water temperature across all flow rates.
Energy Savings – elimination of standby tank losses (0.350 kWh per day).
Unlimited hot water supply.
Smaller Tankless Water Heater Installation space required.
Unit Meets UL and other standards for system contact with potable hot water.
Less peak demand contribution than "storage type" electric water heaters (element controls are energized only for short periods while tank elements are energized during use and recovery).

Power Quality, April 22, 1997
Delmarva Power (now Conectiv)

Tankless Water Heater Test Report

by David B. Vannoy
Manager, Power Quality Services

Delmarva Power

"…test consisted of the following: starting with cold pipes, the tub hot water faucet was turned to the full open position. Water was run for about four minutes. Voltage and current were monitored using an RPM Omega power monitoring system…"

Voltage:

"…The fluctuation between the voltage minimum and maximum resulting from current modulation as the RMS current dropped from its initial peak to the succeeding minimum is approximately 1.8 volts or 0.7%…"

Current:

"…the initial current of approximately 117 amperes fell off to 20 amperes and returned to a peak of approximately 90 amperes. It then oscillated between 60 and 90 amperes during the remainder of the test. The period of this oscillation is such that it does not seem to produce noticeable flicker. …there is no appreciable current waveform distortion,,,"

Voltage Harmonic Distortion:

"…the maximum voltage harmonic distortion to be a maximum of 1.4%."

Flicker:

"Flicker appears to be substantially reduced from earlier models…"

4. Comparative Study, Executive Summary, December 1987
Southern California Edison, SDSU

Comparative study between the Aqua Systems electric instantaneous water heaters, a conventional, residential Title-24 electric storage-type water heater, and a conventional, residential Title-24 natural gas storage-type water heater.

by Sandra Ellis
submitted to:
SDSU Energy Engineering Institute,
Department of Mechanical Engineering,
San Diego State University
San Diego, CA 92182

EXECUTIVE SUMMARY

"The objective of this project was to perform a comparative study between electric storage-type, gas storage-type, and electric instantaneous water heaters for residential energy customers in the Southern California Edison service territory."

"In new construction and in retrofit applications, it was determined that all three models of the Aqua Systems electric instantaneous water heaters, Models R22, R25, and R28, were not only more energy efficient but were also more cost-effective than the electric storage-type water heater tested, even with an additional insulation blanket installed…"