PERFORMANCE

2024-11-22 — PERFORMANCE FEATURES. □ Saves Space – up to 93% smaller than a standard electric water heater. □ Saves Energy – zero standby heat loss when installed near ...

Specification Sheet

Rheem Tankless Electric Water Heaters - Performance Series Tankless Electric RETEX-24, RETEX-27 kW - RETEX-27 (derated 208V performance)* - Rheem Manufacturing Company

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PERFORMANCE®

Rheem® PERFORMANCE® RETEX Tankless Electric Water Heaters
Provide Continuous Hot Water in a Durable, Space-Saving Design
RETEX - 18, RETEX - 24, RETEX - 27, RETEX - 36 tankless electric water heaters are ideal for new construction builds and all applications in the home including pointof-use installation. The durable, compact design allows installation in tight spaces. In warmer climates, these models provide enough hot water to run multiple fixtures simultaneously. To select a unit that meets electrical and hot water gallons per minute (GPM) requirements, please use the sizing guide.

WHOLE HOME

PERFORMANCE FEATURES
n Saves Space ­ up to 93% smaller than a standard electric water heater
n Saves Energy ­ zero standby heat loss when installed near the point-of-use
n More Hot Water ­ up to 4 times the hot water delivery of a standard electric tank (per hour)
n High Efficiency ­ UEF up to .94 and advanced self-modulating technology only consumes the power needed to satisfy hot water demand
n C opper immersion heating elements fit into a multi-chamber design to improve the thermal performance providing better temperature control and faster recovery of hot water
n Copper heat exchanger transfers heat fast and resists corrosion
n Durable powder-coated shell with a galvanized steel backplate
n Brass 3/4" NPT fittings located on the bottom for the inlet and outlet water c onnections provide strength and durability
n Designed to be mounted in an upright position with the inlet and outlet water connections at the bottom of the unit for ease of installation
n Venting is not required to operate, simplifying the installation process compared to a gas tankless water heater
n Digital thermostatic temperature controls in 1-degree increments ranging from 80°F - 140°F (26°C - 60°C)

RETEX - 18 RETEX - 27

RETEX - 24 RETEX - 36

WARRANTY
n Limited Warranty ­ 5 Years - Leaks, 1 Year - Parts
See Use and Care Manual for complete information.

These products meet a stringent set of our company's internally defined sustainability standards.
®

Tested and certified by the Water Quality Association against NSF/ANSI 372 for lead free compliance.

PERFORMANCE® Tankless Electric Specifications and Minimum Requirements

DESCRIPTION

FEATURES

DIMENSIONS (SHOWN IN INCHES)

MODEL NUMBER
RETEX - 18

POWER (kW)

VOLTAGE

TOTAL UNIT AMPERAGE (AMPS)

RECOM'D BREAKER
SIZE

HOUSEHOLD

UNIFORM REQUIRED

ELECTRICAL

ENERGY WIRE

SERVICE PANEL

FACTOR (75°C

RECOM'D PHASE (UEF) INSULATION)

HEIGHT

WIDTH

DEPTH

WATER CONN.

# OF

SHIP

HEATING WEIGHT HEAT

OPERATING

CHAMBERS (LBS.) EXCHANGER PRESSURE

FLOW ACTIVATION RATE (GPM)

18

240

75

2 x 40 A Double Pole

150 AMPS

1

0.94 2 x 8 AWG* 17 14 3.635 3/4" NPT

2

14.78

Copper

Min: 25 PSI Max: 150 PSI

0.3 GPM

RETEX - 24 24

240

100

3 x 40 A Double Pole

200 AMPS

1

0.93 3 x 8 AWG* 17 17 3.625 3/4" NPT

3

17.8

Copper

Min: 25 PSI Max: 150 PSI

0.3 GPM

RETEX - 27 27

240

113

3 x 40 A Double Pole

200 AMPS

1

0.93 3 x 8 AWG* 17 17 3.625 3/4" NPT

3

17.8

Copper

Min: 25 PSI Max: 150 PSI

0.3 GPM

RETEX - 36 36

240

150

4 x 40 A Double Pole

300 AMPS

1

0.94 4 x 8 AWG* 17 21 3.625 3/4" NPT

4

22.7

Copper

Min: 25 PSI Max: 150 PSI

0.3 GPM

NOTE: When converting from an electric tank to an electric tankless water heater, household electric service panel upgrades are often required. Please see the electric service panel recommendations above.

*AWG - American Wire Gauge

11/24 FORM NO. THD-PTE 18-36 REV. 1

RETEX - 18

®
Tankless Electric Water Heaters

RETEX - 24

RETEX - 27

RETEX - 36

13.9"

3.6"

12.9"

17.0"

15.1"

3.6" 17.0"

17.0" 16.0"
15.1"

3.6" 17.0"

17.0" 16.0"
15.1"

3.6" 17.0"

20.8" 19.8"
15.1"

5.9"

5.9"

5.9"

9.8"

SIZING A TANKLESS ELECTRIC WATER HEATER IMPORTANT ­ Verify that your home meets the electrical requirements. See specifications and minimum requirements. (front side)

1 Estimate your total household gallons per minute (GPM) needs by adding up the average flow rates by fixture (showers, faucets, dishwasher, washing machine) that run at the same time.
Ex. 1 shower and 1 kitchen faucet running at the same time adds up to 3.5 GPM (2 + 1.5 = 3.5 GPM)

2 Locate your zone on the map. U.S. Average Ground Water Temperature Zone Map

Average Flow Rates (GPM) by Fixture

Low Flow Faucet

0.5

Bathroom Faucet

1

Kitchen Faucet

1.5

Shower

2

Dishwasher

2

Washing Machine

3

Flow rates may vary.

CAN

AK

HI

PR

Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Zone 8 Zone 9

3 Select the model that can supply you with the estimated total household gallons per minute (Step 1) with the ground water temperature in your zone.

37°F 42°F 47°F 52°F 57°F 62°F 67°F 72°F 77°F
Flow Rate Capacity Table by Zone (Gallons Per Minute - GPM)

Model #

Zone 1 37OF/ 3°C

Zone 2 42OF/ 5°C

Zone 3 47OF/ 8°C

Zone 4 52OF/ 11°C

Zone 5 57OF/ 14°C

Zone 6 62OF/ 17°C

Zone 7 67OF/ 20°C

Zone 8 72OF/ 22°C

Zone 9 77°F/ 28°C

RETEX - 18

1.5

1.6

1.7

1.8

1.9

2.1

2.3

2.6

2.9

RETEX - 24

2.0

2.1

2.2

2.4

2.6

2.8

3.1

3.4

3.8

RETEX - 27

2.2

2.4

2.5

2.7

2.9

3.2

3.5

3.8

4.3

RETEX - 36

3.0

3.1

3.4

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Flow

rates

are

calculated

to

a

set

point

of

120°F.

Ground

water

temperature

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table below. Select the appropriate an optional part to ensure accurate

GPM insert for your model temperature output. To

order, please call customer support 1-800-543-6163

OPTIONAL ­ Flow Regulator Sizing Table by Zone (Gallons Per Minute ­ GPM) The flow regulator fitting threads onto the outlet water connection and limits the outlet flow to the GPM specified in the table. Select the appropriate GPM insert for your model based on your zone. This is an optional part to ensure accurate temperature output.

Model #

Connection kW Size Part #

RETEX - 18 18 RETEX - 24 24 RETEX - 27 27 RETEX - 36 36

¾" NPT ¾" NPT ¾" NPT ¾" NPT

IFR 3-4 IFR 3-4 IFR 3-4 IFR 3-4

Zone 1
37°F/ 3°C
­ 2.0 2.0 3.0

Zone 2/3

Zone 4/5

Zone 6/7

Zone 8/9

42-47°F/ 52-57°F/ 62-67°F/ 72-77°F/

5-8°C 11-14°C 17-20°C 22-28°C

2.0

2.0

2.0

3.0

2.0

3.0

3.0

4.0

2.0

3.0

4.0

5.0

4.0

4.0

5.0

­

NOTE: (­) indicates flow regulator insert is not recommended in this zone.

In keeping with its policy of continuous progress and product improvement, Rheem reserves the right to make changes without notice.

Rheem.com | 800.374.8806

Manufacturers National Service Department

400 Captain Neville Drive, Waterbury, CT 06705

2

11/24 FORM NO. THD-PTE 18-36 REV. 1


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