Rheem RTEX Series Tankless Electric Water Heaters Owner’s Manual

Rheem RTEX Series Tankless Electric Water Heaters

FAQ

• Q: Are electric service panel upgrades necessary when switching to an electric tankless water heater?
  • A: Yes, when converting from an electric tank to an electric tankless water heater, household electric service panel upgrades are often required. Please refer to the recommended specifications above.
• Q: What is the warranty on the tankless water heaters?
  • A: For complete warranty information, please see the Use and Care Manual provided with the product.
• Q: How are the tankless water heaters certified for compliance?
  • A: The products are tested and certified by the Water Quality Association against NSF/ANSI 372 for lead-free compliance.

WHOLE HOME

Provide Endless Hot Water in a Durable, Space-Saving Design

RTEX – 18, RTEX – 24, RTEX – 27, RTEX – 36 tankless electric water heaters are ideal for new construction builds and all applications in the home including point-of-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. All RTEX models include a lifetime limited warranty. To select a unit that meets electrical and hot water gallons per minute (GPM) requirements, please use the sizing guide.

PERFORMANCE FEATURES

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

WARRANTY

• Limited Warranty – 5 Years – Leaks, 1 Year – Parts See Use and Care Manual for complete information.

Specifications

Tankless Electric Specifications and Minimum Requirements

DESCRIPTION| FEATURES| | | DIMENSIONS (SHOWN IN INCHES)|
---|---|---|---|---|---

MODEL NUMBER

| ****

POWER (kW)

| ****

VOLTAGE

| TOTAL UNIT AMPERAGE (AMPS)| ****

RECOM’D BREAKER SIZE

| HOUSEHOLD ELECTRICAL SERVICE PANEL RECOM’D| ****

PHASE

| UNIFORM ENERGY FACTOR (UEF)| REQUIRED WIRE (75°C

INSULATION)

| ****

HEIGHT

| ****

WIDTH

| ****

DEPTH

| ****

WATER CONN.

| ****

# OF HEATING CHAMBERS

| ****

SHIP WEIGHT (LBS.)

| ****

HEAT EXCHANGER

| ****

OPERATING PRESSURE

| ****

FLOW ACTIVATION RATE (GPM)

RTEX – 18| 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
RTEX – 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
RTEX – 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
RTEX – 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

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)
   • 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.

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

Flow Rate Capacity Table

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
---|---|---|---|---|---|---|---|---|---
RTEX – 18| 1.8| 2.0| 2.1| 2.3| 2.6| 2.9| 3.2| 3.7| 4.4
RTEX – 24| 2.4| 2.6| 2.8| 3.1| 3.4| 3.8| 4.3| 5.0| 5.9
RTEX – 27| 2.7| 2.9| 3.2| 3.5| 3.8| 4.3| 4.9| 5.6| 6.6
RTEX – 36| 3.6| 3.9| 4.2| 4.6| 5.1| 5.7| 6.5| 7.5| 8.8

Flow rates are calculated to a set point of 105°F. Ground water temperature varies seasonally.

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.

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.

CONTACT

• Rheem.com
• 800.374.8806
• Manufacturers National Service Department
• 400 Captain Neville Drive, Waterbury, CT 06705

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