Rinnai RE199i Tankless Water Heater User Manual

Rinnai RE199i Tankless Water Heater Manual

Introduction

The Rinnai RE199i Tankless Water Heater is an indoor, gas-fired water heating system designed to provide hot water on demand without storing heated water in a conventional tank. When a hot-water tap opens, the unit detects water flow and activates its electronic ignition system. The heat exchanger then transfers heat to the incoming water, helping deliver a continuous supply for showers, sinks, kitchens, and other household fixtures.

With a maximum input of 199,000 BTU per hour and a Uniform Energy Factor of 0.82, the RE199i is suited to larger homes and applications that require strong simultaneous-flow performance. Its compact wall-mounted design can help preserve floor space, while the indoor configuration allows installation in an appropriate utility room, mechanical room, garage, or similar protected location.

This model supports natural gas or propane and includes integrated temperature controls. It is intended for homeowners, contractors, property managers, and service professionals who need an efficient tankless water heater for everyday domestic hot-water use. Typical applications include replacing a storage-tank heater, supporting multiple bathrooms, and supplying hot water to homes with changing demand throughout the day.

Correct sizing, gas supply, venting, water connections, electrical service, and installation by a qualified professional are essential. Read the complete installation and operation manual before use, and follow all local plumbing, gas, electrical, and building codes.

Rinnai RE199i Specifications and Key Features

• Model: RE199i, indoor residential and commercial tankless water heater.
• Fuel: Natural gas or propane, depending on the exact factory model and configuration.
• Maximum input: 199,000 BTU per hour.
• Minimum input: 10,400 BTU per hour.
• Uniform Energy Factor: 0.82.
• Temperature setting range: 98°F to 140°F under standard operation.
• Dimensions: Approximately 14.05 inches wide, 27.3 inches high, and 11.2 inches deep.
• Electrical requirement: 120 volts AC, 60 Hz.
• Gas connection: 3/4-inch NPT.
• Water connections: 3/4-inch NPT cold-water inlet and hot-water outlet.
• Recommended water pressure: 30 to 80 PSI for strong performance; maximum allowable pressure is 150 PSI.
• Minimum water pressure: 20 PSI.
• Control system: Integrated controller with electronic water-flow and temperature management.
• Installation: Indoor installation with approved venting and adequate combustion-air provisions.

Detailed Description: How the RE199i Works

The Rinnai RE199i heats water only when demand occurs. Opening a hot-water fixture creates flow through the unit, and the flow sensor signals the control system to begin ignition. A modulating gas valve adjusts burner output according to flow rate, incoming-water temperature, and the selected outlet temperature. This process helps reduce standby energy loss associated with storing hot water in a tank.

The unit uses a wall-mounted cabinet, internal burner assembly, heat exchanger, electronic controls, water-flow sensing, and safety-monitoring components. Its compact shape is useful where floor space is limited, but installation still requires service clearance, approved vent materials, condensate or drainage provisions where applicable, and safe access for inspection.

For daily use, set the desired temperature at the controller and open a hot-water tap. Avoid repeatedly changing the setting to excessively high temperatures. Keep the cabinet and surrounding area clear, inspect for unusual sounds or odors, and never block the vent termination or combustion-air openings.

Routine care includes cleaning the inlet water filter, checking connections for signs of leakage, inspecting the vent system, and arranging periodic professional service. In areas with hard water, scheduled flushing of the heat exchanger can help limit mineral scale.

Rinnai RE199i Setup and Installation Guide

Gas, venting, electrical, and plumbing work should be completed by a qualified professional. Incorrect installation can create fire, explosion, carbon-monoxide, scalding, or equipment-damage hazards.

1. Confirm that the unit is the correct fuel version and that the planned location is approved for an indoor installation.
2. Mount the heater vertically on a suitable wall capable of supporting the appliance and connected piping.
3. Install the approved vent system according to the manufacturer’s clearances, termination requirements, and local code.
4. Connect the correctly sized gas line and verify that supply pressure remains within the required operating range.
5. Connect the cold-water inlet, hot-water outlet, isolation valves, pressure-relief equipment, and any required drainage components.
6. Connect the unit to a properly grounded 120-volt electrical supply. Do not use an extension cord.
7. Open the water isolation valves gradually, purge air from the plumbing, and inspect every connection for leaks.
8. Open the gas valve only after the installation has been checked, then test the appliance according to the official manual.
9. Set the controller temperature and verify stable hot-water operation at one or more fixtures.

Do not modify factory wiring, bypass safety switches, obstruct the vent, or attempt gas conversion without approved parts and qualified service. If the heater does not ignite, confirm power, gas supply, water flow, and error indications before contacting a technician.

Troubleshooting the Rinnai RE199i

No Hot Water

• Confirm that the controller has power and that the electrical disconnect or breaker is on.
• Check that the gas supply valve is open and that other gas appliances operate normally.
• Open the hot-water fixture fully enough to create the minimum flow required for activation.
• Verify that the cold-water inlet and hot-water outlet isolation valves are open.

Water Is Too Hot or Too Cold

• Check the controller temperature setting and allow time for the water temperature to stabilize.
• Clean the inlet water filter if reduced flow is suspected.
• Inspect for cross-connection from a mixing valve, single-lever faucet, recirculation system, or plumbing fault.
• Have a qualified technician check gas pressure, water flow, sensors, and the heat exchanger if the problem continues.

Error Codes and Preventive Maintenance

Error codes vary by operating condition and must be interpreted using the official RE-series installation and operation manual. Record the displayed code, turn off the appliance only as directed, and do not repeatedly reset a fault that returns. Never remove the cabinet or service gas components without proper training.

Preventive measures include annual inspection, inlet-filter cleaning, vent inspection, leak checks, and periodic heat-exchanger flushing where mineral buildup is likely. For warranty or technical assistance in the United States, contact Rinnai support at 800-621-9419. Warranty eligibility depends on correct installation, applicable registration requirements, and the terms in the current owner’s guide.

Pros and Cons of the Rinnai RE199i Tankless Water Heater

Advantages

• High heating capacity: The 199,000 BTU maximum input is appropriate for homes with substantial hot-water demand.
• Continuous on-demand operation: It can provide hot water without the finite storage capacity of a conventional tank.
• Space-saving design: The wall-mounted cabinet uses less floor area than many storage water heaters.
• Efficient operation: The 0.82 UEF rating reflects efficient performance for this non-condensing product category.
• Flexible fuel options: Applicable versions support natural gas or propane.
• Adjustable temperature control: The integrated controller allows users to select a practical outlet temperature for different household needs.

Limitations

• Professional installation required: Gas piping, venting, plumbing, and electrical work are more complex than replacing a basic electric tank.
• Indoor installation constraints: The unit needs approved venting, combustion-air provisions, service clearance, and freeze protection where necessary.
• Flow-dependent performance: Very low flow may not activate the heater, while simultaneous high demand can affect outlet temperature.
• Maintenance remains necessary: Hard-water areas may require regular flushing to reduce scale buildup.
• Not ideal for every property: Homes without adequate gas capacity, compatible venting, or sufficient service access may need another water-heating solution.

The RE199i is best suited to larger households and projects that value continuous hot water and compact installation. A storage tank, heat-pump water heater, or different tankless model may be more appropriate when fuel infrastructure, electrical capacity, installation space, or local climate conditions favor another technology.