1. Introduction
This manual provides essential information for the safe and efficient operation, installation, and maintenance of your Rheem Prestige RTGH-84XLN-2 Condensing Tankless Outdoor Natural Gas Water Heater. Please read this manual thoroughly before installation or use and retain it for future reference. Professional installation is required to ensure proper function and to maintain warranty validity.
2. Important Safety Information
WARNING: Improper installation, adjustment, alteration, service, or maintenance can cause property damage, injury, or death. Refer to this manual. For assistance or additional information, consult a qualified installer, service agency, or the gas supplier.
- Always ensure the unit is installed by a qualified professional.
- Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance.
- Ensure adequate clearances are maintained around the unit as specified in the installation instructions.
- This appliance is designed for outdoor installation only.
- In case of gas leak, do not try to light any appliance, do not touch any electrical switch, do not use any phone in your building. Immediately call your gas supplier from a neighbor's phone. Follow the gas supplier's instructions.
3. Product Overview
The Rheem Prestige RTGH-84XLN-2 is a high-efficiency condensing tankless water heater designed to provide continuous hot water for outdoor installations. Key features include:
- Continuous Hot Water: Provides hot water on demand, eliminating the need for a storage tank.
- High Efficiency: .93 UEF (.96 EF Canada) for reduced energy consumption.
- Outdoor Installation: Designed specifically for outdoor use, eliminating the need for indoor venting.
- Low Flow Activation: Activates with a minimum flow rate of .26 GPM and minimum activation flow rate of .40 GPM.
- Ultra Low NOx Burner: Meets SCAQMD rule requirements for low emissions.
- Safety Features: Guardian Overheat Film Wrap, Water & Gas Leak Detection with automatic shutdown and error code display.
- Smart Features: Maintenance notification settings, self-diagnostic system, and EcoNet enabled mobile app feature (additional kit available).
- Included Components: Built-in condensate neutralizer, digital remote control, and 10ft. of thermostat wire.
Figure 3.1: Front view of the Rheem Prestige RTGH-84XLN-2 Tankless Water Heater.
Figure 3.2: Internal view showing the heat exchanger, control board, and other components of the RTGH-84XLN-2.
4. Setup and Installation
Professional installation is mandatory for this appliance. Failure to comply will void the warranty and may result in unsafe operation.
4.1 Pre-Installation Checklist
Before installation, ensure the following:
- Verify inlet and exhaust connection sizes and required materials.
- Confirm the selected unit can deliver the required water temperature for your region.
- Ensure required installed unit clearances are met.
Figure 4.1: Tankless Gas Water Heater Purchase Checklist, highlighting key considerations before installation.
4.2 Replacing a Gas Tank with Tankless
If replacing an existing tank-style water heater, consider the following:
- Venting: Condensing tankless units use PVC and Non-Condensing stainless steel exhaust venting. Your old gas tank's venting may not be compatible.
- Main Gas Line: A 3/4-inch natural gas line is recommended for optimal performance compared to a 1/2-inch line.
- Electricity: Tankless gas water heaters require an electrical power connection, which your old tank may not have needed.
- Piping: Inlet and outlet piping may require alterations to connect the tankless gas water heater.
Figure 4.2: Checklist for considerations when replacing a traditional gas tank water heater with a tankless model.
4.3 Outdoor Installation
This unit is designed for outdoor installation. It includes freeze protection down to -30 degrees Fahrenheit. Ensure the installation location provides adequate space and protection from direct impact, while allowing for proper air circulation.
Figure 4.3: Example of an outdoor installation of a Rheem tankless water heater on a brick wall.
5. Operating Instructions
The Rheem RTGH-84XLN-2 operates automatically to provide hot water on demand. Once installed and connected to gas, water, and electricity, the unit will activate when a hot water faucet is opened.
5.1 Digital Remote Control
The included digital remote control allows you to set the desired hot water temperature. Refer to the separate remote control manual for detailed instructions on its use and programming.
5.2 Low Flow Activation
The unit is designed for industry-leading low flow activation, requiring only 0.26 GPM to sense water flow and 0.40 GPM to activate heating. This ensures hot water is supplied even in low demand situations.
5.3 Performance Guide
The following table provides an estimated performance guide for the RTGH-2 series, including the RTGH-84XLN-2 model, based on water flow and temperature rise. These estimates are for sizing purposes only.
Figure 5.1: Performance Guide for RTGH-2 Series, showing GPM at various temperature rises. Note the RTGH-84 row.
| Model Number | Temperature Rise (°F) | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| 35° | 45° | 50° | 60° | 67° | 70° | 80° | 90° | 100° | |
| RTGH-95 | 9.5 | 8.5 | 7.7 | 6.4 | 5.7 | 5.5 | 4.8 | 4.3 | 3.8 |
| RTGH-90 | 9.0 | 7.7 | 6.9 | 5.8 | 5.2 | 4.9 | 4.3 | 3.8 | 3.5 |
| RTGH-84 | 8.4 | 6.7 | 6.0 | 5.0 | 4.6 | 4.3 | 3.8 | 3.3 | 3.0 |
| RTGH-68 | 6.6 | 5.1 | 4.6 | 3.8 | 3.4 | 3.3 | 2.9 | 2.6 | 2.3 |
Note: Above estimates are for sizing purposes only. Actual performance may vary based on installation and environmental factors.
6. Maintenance
Regular maintenance is crucial for the longevity and efficient operation of your tankless water heater. The unit features maintenance notification settings to remind you when service is due.
- Annual Inspection: It is recommended to have the unit inspected annually by a qualified service technician.
- Condensate Neutralizer: The built-in condensate neutralizer requires periodic inspection and media replacement. Refer to the installation manual for specific intervals.
- Inlet Water Filter: Periodically check and clean the inlet water filter to prevent debris from entering the unit.
- Flushing: In areas with hard water, periodic flushing of the heat exchanger may be necessary to remove mineral buildup. Consult a professional for this procedure.
7. Troubleshooting
The Rheem RTGH-84XLN-2 includes a self-diagnostic system that displays error codes on the digital remote control. If an issue arises, consult the error code list in the full installation and operation manual for specific troubleshooting steps.
- No Hot Water: Check gas supply, electrical power, and water flow. Ensure the remote control is set to a desired temperature.
- Low Hot Water Temperature: Verify the temperature setting on the remote control. Check for excessive hot water demand exceeding the unit's capacity.
- Error Codes: If an error code is displayed, note the code and refer to the comprehensive manual or contact a qualified service technician.
- Water or Gas Leak Detection: The unit will shut down automatically if a leak is detected. Immediately contact a qualified professional for inspection and repair.
8. Specifications
| Feature | Detail |
|---|---|
| Brand | Rheem |
| Model Number | RTGH-84XLN-2 |
| Type | Condensing Tankless Outdoor Natural Gas Water Heater |
| Flow Rate | 8.4 GPM (Gallons Per Minute) |
| Efficiency (UEF) | 0.93 UEF (0.96 EF Canada) |
| BTU Input | 157,000 BTU |
| Voltage | 120 Volts |
| Installation Method | Wall Mount |
| Usage | Outside |
| Special Features | Detection (Water & Gas Leak), Ultra Low NOx, Freeze Protection (-30°F) |
| Product Dimensions (L x W x H) | 27.5 x 9.75 x 28.5 inches |
| Item Weight | 77 pounds |
| Maximum Operating Pressure | 150 PSI |
| UPC | 020352695143 |
Figure 8.1: Dimensions of the Rheem Prestige RTGH-84XLN-2 Tankless Water Heater: 27.5 inches high, 9.75 inches deep, and 18.5 inches wide.
9. Warranty Information
The Rheem Prestige RTGH-84XLN-2 comes with the following warranty:
- Heat Exchanger: 12 years
- Parts: 5 years
- Labor: 1 year
Important: Professional installation is required; otherwise, the warranty will be void.
10. Customer Support
For technical assistance, service, or to obtain a complete copy of the installation and operation manual, please contact Rheem customer support or visit the official Rheem website. Always provide your model number (RTGH-84XLN-2) when seeking support.
You can find more information and support resources on the Rheem Brand Store.