Rinnai REU-KA3237FFUD-US User Manual

Key to Trade Names in this Manual:
RC & RU-Indicates condensing water heater
models.
Model with
valves in carton
Equivalent Model
RC80e RC80HPe
RC80i RC80HPi
RC98e RC98HPe
RC98i RC98HPi
Some of the trade names for models were changed
to indicate that their cartons included isolation valves
and a pressure relief valve. For service and repair
purposes the table below shows the equivalent
models.
RC80HPe
9 15 20 22 25 28 31
RC80HPi
9 15 20 22 25 28 34
RC98HPe
11 16 20 22 25 28 37
RC98HPi
11 16 20 22 25 28 40
RU80e
13 17 21 23 27 29 43
RU80i
13 17 21 23 27 29 43
RU98e
13 17 21 23 27 29 43
RU98i
13 17 21 23 27 29 43
DIAGNOSTICS
WIRE DIAGRAM
GAS CONTROL
FAN
PC BOARD
WATER FLOW
CONTROL
HEAT
EXCHANGER
MODELS
This manual provides service information for the models
below. This table cross references each model to the
applicable page number for internal component
replacement instructions.
Condensing Tankless Water Heater Service Manual
KA Condensing KB Condensing
100000354

Rinnai REU-KA3237FFUD-US Specifications

General

Brand	Rinnai
Model	REU-KA3237FFUD-US
Category	Water Heater
Language	English

Summary

General Information

Safety Definitions

Explains safety alert symbols and hazard classifications.

Using this Manual

Provides guidance on manual usage and references.

Technical Support

Information on contacting technical support.

Recommended Tools

Lists necessary tools for servicing.

Specifications

Diagnostic Codes

Explains how the unit displays error codes for diagnosis.

Accessing Operating Information

How to view error codes and operating data on the controller.

Diagnostic Codes

Operation

Details the sequence of water heater operation modes.

KA Series Electrical Diagnostic Points

Heat Exchanger and Outgoing Water Temperature Thermistors

Testing thermistors for heat exchanger and water outlet.

Frost Protection

Information on frost protection heaters.

Amp Fuses

Guidance on checking the inline fuse.

Flame Rod

Procedure for testing the flame rod.

KB Series Electrical Diagnostic Points

Heat Exchanger, Outgoing Water Temperature and Inlet Thermistors

Testing thermistors for heat exchanger and water/inlet.

Frost Protection

Information on frost protection heaters.

Amp Fuses

Guidance on checking the inline fuse.

Flame Rod

Procedure for testing the flame rod.

KA Series Wiring Diagram

KB Series Wiring Diagram

Flushing the Heat Exchanger

Manual Draining of the Water Heater

KA Series Component Replacement Instructions

Gas Control Assembly

Steps for replacing the gas control assembly.

Fan

Instructions for replacing the fan motor.

PC Board

Steps for replacing the main control board.

Water Flow Control Assembly

Instructions for replacing the water flow control assembly.

Heat Exchanger

Procedures for replacing the primary or secondary heat exchanger.

KB Series Component Replacement Instructions

Gas Control Assembly

Steps for replacing the gas control assembly.

Combustion Fan Motor

Instructions for replacing the combustion fan motor.

PC Board

Steps for replacing the main control board.

Water Flow Control Assembly & By-Pass Control Assembly

Procedures for replacing flow control and bypass assemblies.

Heat Exchanger

Steps for removing and replacing the heat exchanger.

KA Series Gas Pressure Setting Procedure

KB Series Gas Pressure Setting Procedure

KB Series Manifold Gas Pressure Settings

KA Series Dip Switch Settings

KB Series Dip Switch Settings