Rinnai RUC80i, RUC98i RU80e, RU98e Troubleshooting guide

15/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
Rinnai Condensing Tankless
Water Heater Training Program
Level III
Service Fundamentals

25/4/2018
© 2014 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
The following Rinnai Condensing
Tankless Water Heater Level III,
Service Fundamentals course is
approved for NATE continuing
education units in the following
specialties.
Efficiency Analyst Senior –6 units
Gas Heating (Air) Installation –6 units
Gas Heating (Air) Service –6 units
HVAC Performance Verifier –6 units
Hydronics Gas Installation –6 units
Hydronics Gas Service –6 units
Hydronics Oil Installation –6 units
Hydronics Oil Service –6 units
Oil Heating (Air) Installation –6 units
Oil Heating (Air) Service –6 units
If you require credit
for NATE, please
notify the instructor.

35/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
Rinnai SE+and Commercial Series Condensing
Water Heaters.
C199
Commercial
Series
RU/RUC/RUR
SE+Series.

45/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
Rinnai Service and Support (800-621-9419)
➢CRC –Consumer Response Center –general calls, consumer questions, etc.
Available from 8 a.m. to 8 p.m. EST, Monday –Friday.
➢Parts Department –parts orders.
Available from 8 a.m. to 8 p.m. EST, Monday –Friday.
➢Warranty Department –warranty claim issues.
Available from 8 a.m. to 5 p.m. EST, Monday- Friday.
➢Technical Support Department –technical issues related to the function and repair of Rinnai
products.
Available in the office from 8 a.m. to 8 p.m. EST, Monday –Friday AND 24/7/365 on call support for
technicians who are at the service location. Technicians only, call 1-888-RINNAIS ( 888-746-6247)
➢Engineering / Applications Department –calls related to product use and applications
including sizing.
Available from 8 a.m. to 5 p.m. EST, Monday - Friday.
Rinnai America also provides the following websites for support:
•www.rinnai.us –for installation manuals, product specifications and supporting documents. More technical information is
available in the “Partner Portal” section of the website. Registration is required for access.
•www.trainingevents.rinnai.us –to register for Rinnai product training live and online classes and videos. Service manuals,
installation manuals and other technical documents are available under the “Resources” section of the site.

55/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
Model
Designation Full Model Number Min
Btu’s
Max
Btu’s
Min
Activation
Flow Rate
(approx.)
Max Flow
Rate 35°
Rise
Max Flow
Rate 50°
Rise
Max Flow
Rate 70⁰
Rise
UEF
Rating
RUC80i REU-KBD2530FFUD-US 15.2K 152K 0.4 GPM 8.0 GPM 6.0 GPM 4.2 GPM .92
RU80e REU-KB2530WD-US
RUC90i REU-KBD2934FFUD-US 15.2K 180K 0.4 GPM 9.0 GPM 6.9 GPM 5.0 GPM .92
RU90e REU-KB2934WD-US
RUC98i REU-KBD3237FFUD-US 15.2K 199K 0.4 GPM 9.8 GPM 7.6 GPM 5.4 GPM .92
RU98e REU-KB3237WD-US
RUR98i REU-KBP3237FFUD-US 15.2K 199K 0.4 GPM 9.8 GPM 7.6 GPM 5.4 GPM .92
RUR98e REU-KBP3237WD-US
Specifications: SE+and Commercial series.
SE+and Commercial Series: Condensing models.
C199i REU-KBD3237FFUDC-US 15.2K 199K 0.4 GPM 9.8 GPM 7.6 GPM 5.4 GPM 96%
Thermal
Efficiency
C199e REU-KBD3237WDC-US

65/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
Before Performing Service:
•Disconnect the electrical power source.
•Shut off the gas supply.
•Shut off the water supply and drain down the system.
Note:
1. All components in Rinnai tankless water heaters are field replaceable.
2. All major replacement parts are accompanied with replacement procedures.
3. Rinnai will pay reasonable labor for warranty parts changed during the labor warranty
period. Normally one hour labor will be paid for most parts and two hours for the heat
exchanger.
General Service Instructions:

75/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
For service, troubleshooting, and component replacement, the following primary service
tools will be needed (other hand tools might be needed on occasion).
Long #2
Phillips Head
(magnetic)
Small
Phillips
Head U-
Tube Digital Multimeter
(Volt/Ohm Meter)
Screw Drivers Manometer
and or
If Rinnai technical support assistance is required please have these tools available in order to
speed up the troubleshooting process. Also, Rinnai needs to know the full model and serial
number of the product. Have the front cover removed from the product, record and provide any
relevant information such as gas pressures, set temperature, fault codes etc. The service
provider should utilize the tech sheet and/or service manual to troubleshoot the product as
much as possible prior to the call.
Primary Service Tools

85/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
Water Heater
DISASSEMBLY & REASSEMBLY
The following procedures are for KB series water heaters.
Other Rinnai models may vary slightly in design and service requirements.
Please refer to each model’s install guide and service documentation for
model specific information.
PLEASE STAY WITH THE PRESENTATION DURING DISASSEMBLY AND
REASSEMBLY.

95/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
Front Panel Removal
To remove front cover press on the
plastic strip roughly 3” down from the top
of the unit and 3” up from the bottom.
(See circles shown for approximate position).
Slide the plastic strips to the side to
remove from the unit. This will expose
the 4 screws securing the front cover.
Removing the four Phillips head screws
and remove the front cover.

10 5/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
Front Panel Information
Located inside the front cover panel of
all Rinnai Tankless water heaters you
will find a wiring diagram and technical
data sheet. The technical data sheet
contains operation, troubleshooting and
service information including:
•Error code information
•Dip switch/gas pressure settings
•Electrical component test values
•Temperature controller information
•Parts breakdown and part numbers
Technical data sheet
Wiring diagram

11 5/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
1. For internal models, with the front
panel removed, slide the temperature
controller upwards in the mounting
bracket. Pull the bottom of the
controller forward so that the lower tab
is clear. Slide the controller down to
remove. The integrated controller is
connected to the PCB with a 15 wire
harness. The controller can be placed
to the side if it does not need to
removed completely.
2. Any additional controllers or controllers
for external units will be connected to
the “terminals for controls” on the PC
board. DO NOT connect the 120 volts
AC power supply to these terminals.
3. Remove the controller mounting
bracket by removing the power wire
clamp and the ground wire then the
two screws at the bottom of the
bracket.
1
Temperature
controller for
Internal models
2
Temperature controller
3

12 5/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
Overheat Protection and Safeties
1. Heat exchanger outgoing hot water thermistor: Located at
the middle left side of the heat exchanger. This thermistor
monitors water temperature leaving the heat exchanger. This
will be the hottest water in the unit. If the water temperature
gets too hot (close to boiling point) the burners will be
turned Off.
1
2. Hot water outlet thermistor:
Located in the hot water outlet
fitting at the bottom of the
unit. If the outlet water
exceeds the set temperature
by 6⁰F -8⁰F the burners will be
turned Off.
2

13 5/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
Overheat bi-metal switch(es) are placed at various locations inside the
water heater to monitor for overheat conditions.
1. Overheat switch #1 is attach to a copper pipe on the right just above the
secondary heat exchanger. This switch opens at 207⁰F causing water
heater shut down with a code 14. The switch will close after the unit
cools. The unit must be reset by stopping water flow or turning the unit
OFF then ON a the controller.
2. Burner overheat switches #2 are located at the top, back side of the
burner assembly. There are two switches wired in series. These switches
open at 302⁰F causing water heater shut down with a code 57. These
switches will close after the unit cools but the water heater must be reset
by disconnecting and reapplying electrical power.
3. Secondary Heat Exchanger overheat switches #3 are located on the back
of the secondary heat exchanger on either side of the exhaust duct.
There are two switches wired in series. These switches open at 212⁰F
causing water heater shut down with a code 58. These switches will close
after the unit cools but the water heater must be reset by disconnecting
and reapplying electrical power.
Overheat Protection and Safeties
1
23
2
3

14 5/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
1. The thermal fuse wraps around the copper
portion of the heat exchanger assembly. This
device’s primary function is to monitor for high
temperatures in the water heater cabinet due to
physical damage to the heat exchanger that
would allow hot exhaust gasses to escape.
➢The thermal fuse will open at 264⁰F.
➢If the thermal fuse opens the water heater will
shut down with a code 14.
➢The thermal fuse is a “one-time-use” component
and must be replaced once open. It will not reset.
Replacement will require removal of the heat
exchanger. This allows the service provider to
inspect the entire heat exchanger assembly for
damage.
*The thermal fuse and overheat bimetal switch
are wired in series and are replaced as one
component.
Overheat Protection and Safeties
An open thermal fuse or bi-metal switch is a symptom of an underlying issue such as a failed/damaged heat
exchanger, scale buildup inside the copper tubing, dirty or clogged heat exchanger, improperly set gas
pressures, incorrect gas type or an improper gas type conversion. The cause of this symptom should be
investigated to prevent further problems.
1
*

15 5/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
The Rinnai Safety “Line of Defense”
Multiple layers of technology ensure safe operation
If the heat exchanger
thermistor detects
unusually slow heat
dissipation after the
flame stops…
If the outlet
thermistor detects
6-8⁰F over the
temperature set
point…
If the overheat
bimetal detects
207⁰F, 212⁰F, or
302⁰F (depending on
which bi-metal opens)…
If the heat exchanger
thermistor detects a
boiling condition
(approx. 210⁰F)…
If the thermal
fuse detects
264⁰F…
An LC warning code will
post on the temperature
controller (unit will shut
down but can be reset,
see procedure in the
fault code section)
The flame will
turn off until the
temperature
decreases (no
code is posted)
The safety circuit is
broken and a code 14,
57 or 58 will post on
the controller and the
unit will shut down
The flame will
turn off until the
temperature
decreases (no
code is posted)
The safety circuit
is broken and a
code 14 will post
on the controller
and the unit will
shut down.
Overheat Protection and Safeties

16 5/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
The freeze protection system on the RU/RUC and C199
model water heaters consists of electrically powered
ceramic heater elements installed on several pipes and
fittings inside the water heater cabinet.
➢Heater activation is triggered by the outside air
temperature thermistor (thermistor #1) and/or the
intake air temperature thermistor (thermistor #2).
❖Thermistor #1 (indoor and outdoor models) measures
the air temperature outside of the water heater
cabinet.
❖Thermistor #2 (indoor models only) measures the air
temperature coming into the cabinet through the vent
system.
➢Heaters are turned on when thermistor #1 or #2
detects air temperatures below 39⁰˚F.
❖The main circuit board will cycle the heaters On and Off
on a specific cycle based on the air temperature.
NOTE: Adequate incoming power is required for the
freeze protection system to operate correctly!
Freeze Protection Operation
Thermistor #2
Thermistor #1
Ceramic Heater examples

17 5/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
NOTE: It is important the water heater is
disconnected from the electrical power supply prior
to removing the fan assembly otherwise damage to
the fan control circuit could occur.
1. Disconnect the fan electrical connector.
2. Remove the screw or plastic rivet securing the fan air
inlet tube. Remove the tube.
3. Remove the two screws securing the fan assembly
to the burner assembly. Slide the fan forward and out
of the cabinet.
3
1
2
Combustion Fan

18 5/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
The burner assembly is located at the top of the Heat Exchanger assembly. Attached to
this assembly are the…..
1. Gas Manifold.
a. Solenoid valves.
b. Gas pressure test port.
c. Gas supply tube.
2. Sight Glass Plate.
a. Flame rod.
b. Thermocouple.
c. Igniter electrode.
d. Sight glass.
Gas Manifold Assembly / Sight Glass Assembly
1
1a 1a 1a
1b 1c
2
2a 2b 2c 2d

19 5/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
3
2
1
Sight Glass Assembly Removal
1. Disconnect the flame rod wire (yellow) by pulling up.
2. Remove the burner thermocouple by removing the single attachment screw and pulling the
assembly out of the burner assembly. If the thermocouple needs to be completely removed
from the unit, follow the red and white wire harness until you come to a connector. Disconnect
the connector.
3. Disconnect the igniter electrode by pulling straight up on the heavy black wire. Remove the
silicon insulator boot by pulling out to the front.
4. Remove the sight glass
plate by removing the 5
screws securing it to the
burner assembly and
pulling the plate out away
from the unit.
NOTE: The gasket
underneath must be
replaced prior to
reassembly.

20 5/4/2018
© 2016 Rinnai America Corporation
PROPRIETARY and CONFIDENTIAL
Enhancing Lives By Changing The Way Water Is Heated
SV2 SV1 SV3
Gas supply
pipe
Manifold Assembly Removal
1. Disconnect the wiring and remove the thermocouple as outlined on the previous slide (the sight
glass plate can stay in place).
2. Disconnect the wiring harnesses from the solenoid valves: SV1 (black & blue), SV2 (black &
yellow), SV3 (black & red).
3. Disconnect the gas supply pipe by removing the single screw holding the retaining clip.
Remove the clip and pull the gas line to the right until is clears the manifold. Ensure the o-ring
is intact. (for reassembly, ensure the o-ring is on the supply pipe and not inside the manifold
opening. This will reduce the possibility of the o-ring being cut upon reassembly.
4. Remove the 10 screws
securing the manifold to
the burner assembly.
5. Pull the manifold forward
away from the unit.
6. Inspect the gasket
underneath for any
damage.