GFX Tested Performance

DOEs Uniform Test Method for Water Heaters: 10CFR Pt. 430, Subpt. B, App. E

 

Final Report: Virginia Power Water Heater Testing and Optimization Project 

Part 3: Virginia Powers Evaluation of a Drain Water Heat Recovery Device

Outperforms heat pump water heater" (EDU 12/96)

Gives an electric water heater the capacity of a gas heater (EDU 12/96)

 

Measured Performance of 5 Electric PFWHs

(Power Feedback Water Heaters) using a Model G3-60 GFX

WATER HEATER

(#1,2,3 all 50 gal)

ENERGY FACTOR (EF)

STANDING LOSS (Btu/hr)

FIRST HOUR RATING (gallons)

1. Standard

1.3 +/-0.125

220

108*

2. Plastic

(Hi-Eff.)

1.51 +/- 0.31

193

180*

3. Stone Lined (Hi-Eff.)

1.6 +/- 0.11

178

180*

4. Tankless (13.5 kW)

1.8 +/- 0.1

NIL

Continuous @

2.2 gpm

5. Point-of-Use (2.5 gal.)

N/A

N/A

2 to 3 gal. @ 2.2gpm

* Estimated because GFX prevented upper element energization during standard draw test.

HPWH Performance with E-Techs Add-on Heat Pump (HP)

WATER HEATER

EF**

STANDING LOSS

FIRST HOUR RATING

1. Standard

1.28 +/- 0.16

260

46

2. Plastic

1.365 +/- 0.155

165

58

3. Stone-Lined

1.45 +/- 0.12

127

60

** Outperforms heat pump water heater
The Old Dominion GFX study was part of a larger project to evaluate several electric water heating technologies, including heat pump water heaters. When the results for the GFX are compared to those for heat pump water heaters, the GFX looks better. For the three electric heaters tested, the measured energy factor was higher with the GFX than with an add-on heat pump water heater (see Figure 4). These results do not conclusively show that the GFX will outperform a heat pump water heater in the field, however, because of complexities like batch usage and water temperature. Nonetheless, given the much lower cost of the GFX, it appears to be a practical alternative to heat pump water heaters.@ (Quote from Extraordinary Water Heat Recovery Device, Energy Design Update, December 1996)


Performance of all 5 Electric Water Heaters without GFX or HP

WATER HEATER

EF

STANDING LOSS

FIRST HOUR RATING

1. Standard

0.845 +/- 0.015

339

46

2. Plastic

0.915 +/- 0.015

359

58

3. Stone Lined

0.92 +/- 0.01

134

60

4. Tankless

0.99 +/- 0.01

NIL

1.5 gpm

5. Point-of-Use

N/A

N/A

1.25 to 1.6

KEY CONCLUSIONS

"The GFX drain water recycling unit is an extremely effective heat exchanger. Its measured effectiveness (recycling efficiency) was very close to that specified by the manufacturer at 60 percent."

"When properly installed, the GFX reduces energy consumption at varying load patterns from 47 to 64 percent with the average being 55 percent."

"GFX can increase the energy factor from 57 to 73 percent over resistance water heaters alone."

"Resistance water heaters utilizing GFX as a pre-heater can produce Approximate First Hour Ratings of 108 to 180 gallons; about two to three times that of resistance water heaters alone."

"With a drain water temperature near 100 degrees F the GFX can increase the temperature of the water entering the water heater from 20 degrees F to 30 degrees F depending on inlet water temperatures."

"GFX provides enough energy to the inlet water to prevent the upper element energization (fast recovery cycle). This occurred in all tests with the three resistance water heaters."

"In typical 24-hour hot water draw profiles the" tankless water heater" combined with the GFX as a preheater consumed approximately 36 percent less energy than Water Heaters #1 and #2 combined with the GFX and 18 percent less than Water Heater #3 with the least standby losses."

 

  1. Reference: "Virginia Power Water Heater Testing and Optimization Project", Final Report (May 31, 1996) by Douglas Taylor and Prof. Gary Crossman, College of Engineering and Technology, Old Dominion University, Norfolk, VA 23529.
  2. Was estimated since so much energy was recycled the "First Hour Ratings could not be calculated for GFX because the upper element did not energize."
  3. Estimated from an average measured energy savings of 36% , 18% compared to #1 & #3, respectively.

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2002 Waterfilm Energy, Inc.