1

Tankless Water Heaters – Deemed Savings Issues

May 7, 2002

2

Savings Depend Upon “Going Completely Tankless”

• Savings from “tankless” water heater result from the elimination of “standby losses”

• Tankless water heaters must be provide for “whole-house” hot water needs to eliminate the need for standard storage tank

3

Maximum Potential Average Energy Savings from Tankless Electric Water Heaters

• If ALL Standby losses are eliminated on a 50 gallon tank located annual savings = – 461 kWh/yr (for tanks located outside heated space)– 368 kWh/yr (for tanks located inside heated space)*

• Post-January 2004 savings =– 293 kWh/yr (Outside)– 229 kWh/yr (Inside)

*Weighted for saturation of electric water heating in non-electrically heated homes

4

“Whole-House” & “Point-of-Use”Similar kWh, Different KW

• Multiple “point-of-use” tankless waters and single “high-capacity” tankless water heaters can produce roughly equivalent savings

• Multiple “point-of-use” water heaters will produce lower “peak-load” impacts than single “high-capacity water heaters.

5

“Point-of-Use” Tankless Water Heater Capacities

Capacity (KW) Maximum Flow @ 115 F (gpm)

12.0 0.92

9.0 0.72

6.0 0.52

1.3 0.11

6

Whole-House Tankless Water Heater Capacities

Capacity (KW) Maximum Flow @ 115 F (gpm)

Maximum Flow @ 105 F (gpm)

28 3.2 3.8

22 2.1 2.6

18 1.8 2.4

16 1.6 2.2

14 1.4 2.0

7

Standard Tank Daily Load Profile

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24Time of Day

KW

/HR

Average Weekday

Average Weekend

8

“Whole-House” Tankless Water Heater Daily Load Profile

• To Be Developed