Rinnai RUC80i, RUC98i RU80e, RU98e User manual

Direct Vent Tankless Water Heater
Operaon Instrucons
Important Facts about your Water Heater
Thank you for purchasing a Rinnai Tankless Water Heater. For proper operaon and safety, it is
important to follow the instrucons and adhere to all safety precauons.
Read all of the instrucons and the warranty thoroughly before operang this water heater. Keep this
manual in a safe place.
NOTICE: Rinnai somemes shares customer contact informaon with businesses that we believe provide
products or services that may be useful to you. By providing this informaon, you agree that we can
share your contact informaon for this purpose. If you prefer not to have your informaon shared with
these businesses, please contact customer service and ask not to have your informaon shared. We
will however, connue to contact you with informaon relevant to the product(s) you registered and/or
you account with us.
—Do not store or use gasoline or other ammable vapors and liquids in the vicinity of this or any
other appliance.
—WHAT TO DO IF YOU SMELL GAS
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
instrucons.
If you cannot reach your gas supplier, call the re department.
—Installaon and service must be performed by a licensed professional.
If the informaon in these instrucons is not followed exactly, a re or
explosion may result causing property damage, personal injury, or death.
WARNING
FOR INDOOR APPLICATIONS ONLY
RUC80i .................. REU-KBD2530FFUD-US
RUC90i .................. REU-KBD2934FFUD-US
RUC98i .................. REU-KBD3237FFUD-US
FOR OUTDOOR APPLICATIONS ONLY
RU80e ................... REU-KB2530WD-US
RU90e ................... REU-KB2934WD-US
RU98e ................... REU-KB3237WD-US
1 of 17

Consumer Operaon Guidelines for the Safe Operaon of your Water Heater
FOR YOUR SAFETY READ BEFORE OPERATING
A. This appliance does not have a pilot. It is
equipped with an ignion device which
automacally lights the burner. Do not try to light
the burner by hand.
B. BEFORE OPERATING smell all around the appliance
area for gas. Be sure to smell next to the oor
because some gas is heavier than air and will
sele on the oor.
WHAT TO DO IF YOU SMELL GAS
Do not try to light any appliance.
Do not touch any electric switch; do not use any
phone in your building.
Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s
instrucons.
If you cannot reach your gas supplier, call the re
department.
C. Use only your hand to push in or turn the gas
control knob. Never use tools. If the knob will not
push in or turn by hand, do not try to repair it, call
a licensed professional. Force or aempted repair
may result in a re or explosion.
D. Do not use this appliance if any part has been
under water. Immediately call a licensed
professional to inspect the appliance and to
replace any part of the control system and any gas
control which has been under water.
TO TURN OFF GAS TO APPLIANCE
1. Turn o all electric power to the appliance using
the ON/OFF buon.
2. Set the thermostat to lowest seng.
3. Locate the manual gas valve on the side of the
heater. Turn the manual valve clockwise to the
full OFF posion.
OPERATING INSTRUCTIONS
1. STOP! Read the safety informaon above.
2. Set the thermostat to lowest seng.
3. Turn o all electric power to the appliance using
the ON/OFF buon.
4. This appliance is equipped with an ignion device
which automacally lights the burner. Do not try
to light the burner by hand.
5. Locate the manual gas valve on the side of the
heater. Turn the manual valve clockwise to the
full OFF posion.
6. Wait ve (5) minutes to clear out any gas. Then
smell for gas, including near the oor. If you smell
gas, STOP! Follow “B” in the safety informaon
above. If you don’t smell gas, go to the next step.
7. Turn the manual gas valve counterclockwise to the
full ON posion.
8. Turn on all electric power to the appliance using
the ON/OFF buon.
9. Set the thermostat to desired seng.
10. Open a hot water tap. If the appliance will not
operate, follow the instrucons “To Turn O Gas
To Appliance” and call your licensed professional
or gas supplier. See manual for addional
informaon.
CLOSE
Manual Valve
OPEN
WARNING If you do not follow these instrucons exactly, a re or explosion
may result causing property damage, personal injury, or loss of life.
2 of 17

How to use the Temperature Controller
The MC-91-2 controller is the standard temperature controller
that is supplied with the water heater. On indoor models it is
integrated into the front panel. The MCC-91-2 controller is for
commercial and hydronic applicaons requiring higher
temperatures. When the MCC-91-2 controller is connected,
these higher temperatures are available on all controller
models in the system. Refer to the secon on temperature
ranges.
DO NOT repeatedly operate the water heater and then use a
hot water tap while the controller is turned o. Operang the
water heater in this way to alternately produce hot water may
cause water to condense on the outside of internal parts and
accumulate in the water heater cabinet. Dimensions (inches): 3.5 W x 4.75 H x 0.75 D
Temperature
Display
Priority
Indicator
Priority
Button
ON/OFF
Button
In Use
Indicator
Temperature
Selection
MC-91-2US
Before operang, smell all around the appliance area for
gas. Be sure to smell next to the oor because some gas
is heavier than air and will sele on the oor.
Keep the area around the appliance clear and free from
combusble materials, gasoline, and other ammable
vapors and liquids.
Always check the water temperature before entering a
shower or bath.
Do not use this appliance if any part has been under
water. Immediately call a licensed professional to
inspect the appliance and to replace any part of the
control system and any gas control which has been
under water.
Should overheang occur or the gas supply fail to shut
o, turn o the manual gas control valve to the
appliance.
Do not adjust the DIP switch unless specically
instructed to do so.
Do not use an extension cord or an adapter plug with
this appliance.
Any alteraon to the appliance or its controls can be
dangerous and will void the warranty.
If you install this water heater in an area that is known
to have hard water or that causes scale build-up the
water must be treated and/or the heat exchanger
ushed regularly. Rinnai provides a “Scale Control
System” that oers superior lime scale prevenon and
corrosion control by feeding a blend of control
compounds into the water supply. Damage and repair
due to corrosive compounds in the air is not covered by
warranty.
Keep the air intake locaon free of chemicals, such as
chlorine or bleach, that produce fumes. These fumes
can damage components and reduce the life of your
appliance. Damage and repair due to scale in the heat
exchanger is not covered by warranty.
WARNING
The water must be potable, free of corrosive chemicals, sand, dirt, or other contaminates. It is up to the installer to
ensure the water does not contain corrosive chemicals, or elements that can aect or damage the heat exchanger. Water
that contains chemicals exceeding the levels below aect and damage the heat exchanger. Replacement of the heat
exchanger due to water quality damage is not covered by the warranty.
Maximum Level
Total Hardness Up to 200 mg / L
Aluminum * Up to 0.2 mg / L
Chlorides * Up to 250 mg / L
Copper * Up to 1.0 mg / L
Dissolved Carbon Dioxide (CO2) Up to 15.0 mg / L or PPM
Iron * Up to 0.3 mg / L
Manganese * Up to 0.05 mg / L
pH * 6.5 to 8.5
TDS (Total Dissolved Solids) * Up to 500 mg / L
Zinc * Up to 5 mg / L
* Source: Part 143 Naonal
Secondary Drinking Water
Regulaons
3 of 17

How to Set the Temperature
While any hot water is being provided,
the temperature seng can only be
adjusted between 98° F and 110° F.
NOTICE
Check local codes for the maximum water
temperature seng allowed when used
in nursing homes, schools, day care
centers, and all other public applicaons.
NOTICE
If a newly installed unit with a controller
has not been powered for at least 6 hours
then the temperature will return to the
default seng of 104° F (40° C) if power is
interrupted.
NOTICE
There may be a variaon between the
temperature displayed on the
temperature controller and the
temperature at the tap due to weather
condions or the length of pipe to the
water heater.
NOTICE
1. If the water heater is o, press
the Power buon to turn on.
2. If the Priority light is o, then
press the “Priority buon” on the
temperature controller. The
orange Priority light will glow
indicang that this controller is
controlling the temperature and
that the water heater is ready to
supply hot water. (The priority
can only be changed while no hot
water is running.)
3. Press the up or down buons to
obtain the desired temperature
seng.
All hot water sources are able to
provide water at this temperature
seng unl it is changed again at
this or another temperature
controller.
DANGER
Water temperatures over 125° F (52° C) can cause severe burns or scalding
resulng in death.
Hot water can cause rst degree burns with exposure for as lile as:
3 seconds at 140° F (60° C)
20 seconds at 130° F (54° C)
8 minutes at 120° F (49° C)
Children, disabled, or elderly are at highest risk of being scalded.
Feel water before bathing or showering.
This water heater requires a minimum ow rate to operate. This rate can be found on the specicaon page in
this manual. In some cases when you are not geng hot water or if the water alternates between hot and cold,
it is due to the water ow being below or close to the minimum ow rate. Increasing the ow rate should
resolve these problems in these cases.
If you are experiencing issues with higher temperature sengs, then reduce the temperature seng. Selecng a
temperature closer to that which is actually used at the faucet will increase the amount of hot water being
delivered to the faucet, due to less cold water mixing at the xture.
4 of 17

Temperatures Available with a Controller
The water heater can deliver water at only one temperature seng at a me. The available temperatures are
provided below. A temperature lower than 98° F (37° C) can be obtained at the tap by mixing with cold water.
To change the temperature scale from Celsius to Fahrenheit or vice versa, press and hold the “On/O” buon
for 5 seconds while the water heater is OFF.
These temperatures are suggesons only:
* Temperature sengs from 125-140 °F (52-60 °C) are available by seng SW6 in DIPSW 1 to ON. These
models have a default maximum temperature of 120° F (49° C) and an opon (SW6) to increase the
maximum temperature to 140 °F (60 °C).
DO NOT adjust the other switches unless specically instructed to do so.
WARNING
Kitchen 120 °F (49° C)
Shower 98 - 110 °F (37 - 43 °C)
Bath Fill 102 - 110 °F (39 - 43 °C)
Temperature Sengs Available
Fahrenheit °F 98 100 102 104 106 108 110 115 120 125
*
130
*
135
*
140
*
150
**
160
**
185
**
Celsius °C 37 38 39 40 41 42 43 46 49 52 54 57 60 66 71 85
** These sengs require the MCC-91-2 controller. When the MCC-91-2 controller is connected, these higher
temperatures are available on all controller models in the system. Use of an MCC-91-2 controller in a
residenal dwelling will reduce the warranty coverage to that of a commercial warranty applicaon.
Alternate Temperature Sengs
A dierent range of temperature sengs is available by seng SW2 and SW3 in the DIPSW 2 to ON. The table
below shows the sengs available with the MC-91-2 and MCC-91-2 controller.
Alternate Temperature Sengs Available
Fahrenheit °F 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185
Celsius °C 43 46 49 52 54 57 60 63 66 68 71 74 77 79 82 85
MC-91-2
MCC-91-2
MC-91-1, MCC-91-1, MC-100V-1, and BC-100V-1 controllers are not compable with
Alternate Temperature Sengs. Alternate Temperature Sengs are for commercial
applicaons only.
DO NOT use the MC-91-1, MCC-91-1, MC-100V-1, or BC-100V-1 controllers when SW2
and SW3 in DIPSW 2 are in the ON posion.
WARNING
5 of 17

Seng Controller to Mute
On the MC-91-2 to eliminate the beeps when keys are pressed or to turn the beeps back on, press and hold both
the up and down buons unl a beep is heard (approximately 5 seconds).
Locking the Controller
The MC-91-2 controller can be locked by pressing the Priority buon and the up buon together for 5 seconds.
A beep will sound conrming that the controller is locked. The display will alternately show “LOC”, the
temperature seng, and a diagnosc code if one has been acvated. All of the controllers in the system are
also locked.
To unlock the controller press the Priority buon and the up buon together for 5 seconds.
To Display Diagnosc Informaon
To display the most recent diagnosc informaon code press and hold the “On/O” buon for 2 seconds on the
MC-91-2 controller. While holding the “On/O” buon press the up buon. The last 9 diagnosc codes will
ash one aer the other. To exit this mode press the “On/O” and up buon as before.
To enter or exit the maintenance monitor informaon mode, press and hold the down buon for 2 seconds and
without releasing it press the ON/OFF buon.
To obtain the water ow rate: press the up or down buons unl “01” displays. The water ow rate will then
appear. For example “58” means 5.8 gal/min.
To obtain the outgoing water temperature press the up or down buons unl “02” displays. The temperature
will appear in degrees Fahrenheit.
Diagnosc Codes
This water heater is designed to display diagnosc codes. If there is a potenal operaon concern refer to the
code and remedy on the next page.
Data UnitNo.
Water ow rate 0.1 gal/min01
Outgoing water temperature Degrees Fahrenheit02
Temperature Opons Without a Temperature Controller
The default temperature seng for this appliance installed without a temperature controller is 120° F (49° C). If
desired, the temperature seng can be changed to 140° F (60° C) by adjustment of a switch.
Set SW5 in DIPSW 1 to ON to obtain 140° F water temperature seng. Set SW5 to OFF (default) to obtain 120° F
water temperature seng. If a temperature controller is installed, then SW5 has no eect on temperature
sengs.
6 of 17

Diagnosc Codes and Remedies
Code Denion Remedy
03 Power interrupon during Bath
Fill (Water will not ow when
power returns).
Turn o all hot water taps. Press ON/OFF twice.
05 Bypass servo Contact a licensed professional.
10 Air Supply or Exhaust Blockage Check that nothing is blocking the ue inlet or exhaust.
Check all vent components for proper connecons.
licensed
professional
only
Ensure approved venng materials are being used.
Ensure vent length is within limits.
Verify DIP switches are set properly.
Check fan for blockage.
Burner Sensor (see code 31)
11 No Ignion
(heater not turning on)
Check that the gas is turned on at the water heater, gas meter, or cylinder.
If the system is propane, make sure that gas is in the tank.
Ensure appliance is properly grounded.
licensed
professional
only
Ensure gas type and pressure is correct.
Ensure gas line, meter, and/or regulator is sized properly.
Bleed all air from gas lines.
Verify DIP switches are set properly.
Ensure igniter is operaonal.
Check igniter wiring harness for damage.
Check gas solenoid valves for open or short circuits.
Remove burner cover and ensure all burners are properly seated.
Remove burner plate and inspect burner surface for condensaon or debris.
Check the ground wire for the PC board.
12 No Flame Check that the gas is turned on at the water heater, gas meter, or cylinder.
Check for obstrucons in the ue outlet.
If the system is propane, make sure that gas is in the tank.
licensed
professional
only
Ensure gas line, meter, and/or regulator is sized properly.
Ensure gas type and pressure is correct.
Bleed all air from gas lines.
Ensure proper venng material was installed.
Ensure condensaon collar was installed properly.
Ensure vent length is within limits.
Verify DIP switches are set properly.
Check power supply for loose connecons.
Check power supply for proper voltage and voltage drops.
Ensure ame rod wire is connected.
Check ame rod for carbon build-up.
Disconnect and reconnect all wiring harnesses on unit and PC board.
Check for DC shorts at components.
Check gas solenoid valves for open or short circuits.
Remove burner plate and inspect burner surface for condensaon or debris.
14 Thermal Fuse has acvated Check for restricons in air ow around unit and vent terminal.
licensed
professional
only
Ensure SW5 in DIPSW 2 is in the o posion.
Check gas type of unit and ensure it matches gas type being used.
Check for low water ow in a circulang system causing short-cycling.
Ensure dip switches are set to the proper posion.
Check for foreign materials in combuson chamber and/or exhaust piping.
Check heat exchanger for cracks and/or separaons.
Check heat exchanger surface for hot spots which indicate blockage due to scale
build-up. Refer to instrucons in manual for ushing heat exchanger. Hard water
must be treated to prevent scale build up or damage to the heat exchanger.
Measure resistance of safety circuit.
Ensure high re and low re manifold pressure is correct.
Check for improper conversion of product.
16 Over Temperature Warning
(safety shutdown because unit is
too hot)
Check for restricons in air ow around unit and vent terminal.
licensed
professional
only
Check for low water ow in a circulang system causing short-cycling.
Check for foreign materials in combuson chamber and/or exhaust piping.
Check for blockage in the heat exchanger.
Some of the checks below should be done by a licensed professional. Consumers
should never aempt any acon that they are not qualied to perform.
WARNING
7 of 17

Code Denion Remedy
19 Electrical Grounding
licensed
professional
only
Check all components for electrical short.
25 Condensate Trap is full Check condensate trap and drain line for blockage.
licensed
professional
only
Replace condensate trap.
31 Burner Sensor Measure resistance of sensor.
Replace sensor.
32 Outgoing Water
Temperature Sensor
Check sensor wiring for damage.
Measure resistance of sensor.
Clean sensor of scale build-up.
Replace sensor.
33 Heat Exchanger Outgoing
Temperature Sensor
41 Outside Temperature
Sensor
51 Inlet Water Temperature
Sensor
52 Modulang Solenoid Valve
Signal
Check modulang gas solenoid valve wiring harness for loose or damaged terminals.
Measure resistance of valve coil.
57 Burner Contact a licensed professional.
58 Secondary heat exchanger
There is scale build up in the secondary heat exchanger and it needs to be ushed to prevent
damage. Refer to the ushing instrucons in the manual. Hard water must be treated to
prevent scale build up or damage to the heat exchanger.
61 Combuson Fan
Ensure fan will turn freely.
Check wiring harness to motor for damaged and/or loose connecons.
Measure resistance of motor winding.
65 Water Flow Control
The water ow control valve has failed to close during the bath ll funcon. Immediately turn
o the water and disconnue the bath ll funcon. Contact a licensed professional to service
the appliance.
70 PC Board
Check PC board DIP switches for correct posion.
Check the connecon harness at the connecon on the PC board.
Replace PC board.
71 Solenoid Valve Circuit Replace the PC Board.
72 Flame Sensing Device Replace the PC Board.
73 Burner Sensor Circuit Check sensor wiring and PC board to be sure that they have not been damaged.
Replace sensor.
LC #
(LC0,
LC1,
LC2,…)
Scale Build-up in Heat
Exchanger (when checking
maintenance code history,
“00” is substuted for
“LC”)
LC0~LC9 indicates that there is scale build up in the heat exchanger and that the heat
exchanger needs to be ushed to prevent damage. Refer to the ushing instrucons in the
manual. Hard water must be treated to prevent scale build up or damage to the heat
exchanger.
To operate the water heater temporarily unl the heat exchanger can be ushed, push the On/
O buon on the temperature controller 5 mes. Repeated LC codes will eventually lockout
the water heater.
Please call Rinnai technical department.
FF Maintenance has been
performed Indicates a licensed professional performed maintenance or corrected an issue.
No
code
Nothing happens when
water ow is acvated.
Clean inlet water supply lter.
On new installaons ensure hot and cold water lines are not reversed.
Verify you have at least the minimum ow rate required to re unit.
licensed
professional
only
Check for cold to hot cross over. Isolate circulang system if present. Turn o cold water to the
unit, open pressure relief valve; if water connues to ow, there is bleed over in your plumbing.
Verify turbine spins freely.
Measure the resistance of the water ow control sensor.
If the display is blank and clicking is coming from the unit, disconnect the water ow servo
motor (GY, BR, O, W, P, BL, R). If the display comes on replace the water ow servo motor.
8 of 17

The appliance must be inspected annually by a
licensed professional. Repairs and maintenance shall
be performed by a licensed professional. The
licensed professional must verify proper operaon
aer servicing.
Cleaning
It is imperave that control compartments, burners,
and circulang air passageways of the appliance be
kept clean.
Clean as follows:
1. Turn o and disconnect electrical power. Allow to
cool.
2. Close the water shut o valves. Remove and clean
the water inlet lter.
3. Remove the front panel by removing 4 screws.
4. Use pressurized air to remove dust from the main
burner, heat exchanger, and fan blades. Do not
use a wet cloth or spray cleaners on the burner.
Do not use volale substances such as benzene
and thinners. They may ignite or fade the paint.
5. Use so dry cloth to wipe cabinet.
Vent System
The vent system should be inspected at least annually
for blockages or damage. If the vent is blocked
contact a licensed professional.
Motors
Motors are permanently lubricated and do not need
periodic lubricaon. However you must keep fan and
motor free of dust and dirt by cleaning annually.
Temperature Controller
Use a so damp cloth to clean the temperature
controller. Do not use solvents.
Lime / Scale Build-up
If you receive diagnosc code “LC#” (LC1, LC2,…),
refer to the procedure, Flushing the Heat Exchanger.
Refer to the secon on Water Quality to see if your
water needs to be treated or condioned. (When
checking maintenance code history, “00” is
substuted for “LC#”.)
Snow Accumulaon
Keep the area around ue terminal free of snow and
ice. The appliance will not funcon properly if the
intake air or exhaust is impeded (blocked or parally
blocked) by obstrucons.
Coastal Installaons
Installaons located in or near coastal areas may
require addional maintenance due to corrosive
airborne ocean salt.
Clean the water lter
Clean the inlet water lter by closing the cold and hot
water inlet isolaon (shut-o) valves. Put a bucket
under the lter at the boom of the water heater to
catch any water that is contained inside the unit.
Unscrew the water lter. Rinse the lter to remove
any debris. Install the lter and open the isolaon
valves.
Required Maintenance
To protect yourself from harm, before performing maintenance:
Turn o the electrical power supply by unplugging the power cord or by turning o the electricity at the
circuit breaker. (The temperature controller does not control the electrical power.)
Turn o the gas at the manual gas valve, usually located immediately below the water heater.
Turn o the incoming water supply. This can be done at the isolaon valve immediately below the water
heater or by turning o the water supply to the building.
WARNING
Keep the appliance area clear and free from combusble materials, gasoline, and other
ammable vapors and liquids.
WARNING
The appliance must be inspected annually by a licensed professional. Repairs and maintenance shall be performed
by a licensed professional. The licensed professional must verify proper operaon aer servicing.
The following maintenance items are required for the proper operaon of your water heater.
9 of 17

Pressure Relief Valve (PRV):
Operate the PRV manually once a year. In doing so, it
will be necessary to take precauons with regard to
the discharge of potenally scalding hot water under
pressure. Ensure discharge has a safe place to ow.
Contact with your body or other property may cause
damage or harm.
Visual Inspecon of Flame
Verify proper operaon aer servicing. The burner
must ame evenly over the enre surface when
operang correctly. The ame must burn with a clear,
blue, stable ame. See the parts breakdown of the
burner for the locaon of the view ports.
The ame paern should be as shown in the gures
below:
Freeze Protecon
Make sure in case of freezing weather that the water
heater and its water lines are adequately protected to
prevent freezing. Damage due to freezing is not
covered by the warranty. Refer to the secon on
Freeze Protecon. The unit may be drained manually.
However, it is highly recommended that:
drain down solenoid valves be purchased and
installed that will automacally drain the unit if
power is lost. These are available in a kit,
104000059. (The condensate trap drain plug and
water drain plug are not aected by the auto
drain down solenoid valves and will have to be
manually opened.)
a surge protector with terminals be purchased
and installed which allows the solenoid valves to
operate if the unit is disabled due to a diagnosc
code. This is available as 104000057.
Winterizaon
These recommendaons are intended to suggest
pracces that are eecve for winterizing the water
heater. They should be used as a guide only. No
liability is assumed for any issues resulng from the
use of this informaon.
GAS
Shut o the gas to the water heater. It is generally
preferable to shut o the gas service to the enre
locaon if gas is not going to be used.
WATER
Shut o the cold water supply to the water heater. It
is generally preferable to shut o the water to the
enre locaon if water is not going to be used.
Drain the water heater by opening the drain valves on
the cold water line and hot water line.
Open several hot water taps and remove the lter
assembly at the water inlet in order to allow room for
expansion in case there is water in the lines that
freeze.
ELECTRIC
Disconnect the power supply by either unplugging the
electrical cord or by turning o the circuit breaker to
the water heater to prevent potenal damage from
irregular power surges or interrupons.
VENT TERMINATION
Place a cover over the vent terminaon (intake and
exhaust) if it can be safely accessed. The cover should
be easy to apply and remove. This will prevent
debris, leaves, and small animals from entering the
venng and water heater which could cause air ow
issues upon return to service.
SATISFACTORY
UNSATISFACTORY
FRONT VIEW
YELLOW
FLAME ROD
FRONT VIEW
BLUE
FLAME ROD
Tesng the pressure relief valve should only be
performed by a licensed professional. Water
discharged from the pressure relief valve could cause
severe burns instantly or death from scalds.
WARNING
10 of 17

Water Heater
Pressure Relief Valve
3/4" Ball Valve
3/4" Union
Check Valve
S
Pressure Regulator
Circulating Pump
Solenoid Valve
Boiler Drain Valve
KEY
G a s
Sup
p ly
V1
V3
V2
V4
H1
H2
H3
Circulating Pump
Cold
Water
Line
Hot
Water
Lin
e
n
-line
Filter
I
Rinnai
An LC0~LC9 or “00” or 58 diagnosc code indicates the unit is beginning to lime up and must be ushed. Failure
to ush the appliance will cause damage to the heat exchanger. Damage caused by lime build-up is not covered
by the unit’s warranty. Rinnai strongly recommends installaon of isolaon valves to allow for ushing of the
heat exchanger.
1. Disconnect electrical power to the water heater.
2. Close the shuto valves on both the hot water and
cold water lines (V3 and V4).
3. Connect pump outlet hose (H1) to the cold water
line at service valve (V2).
4. Connect drain hose (H3) to service valve (V1).
5. Pour 4 gallons of undiluted virgin, food grade, white
vinegar into pail.
6. Place the drain hose (H3) and the hose (H2) to the
pump inlet into the cleaning soluon.
7. Open both service valves (V1 and V2) on the hot
water and cold water lines.
8. Operate the pump and allow the vinegar to circulate
through the water heater for at least 1 hour at a rate
of 4 gallons per minute (15.1 liters per minute).
9. Turn o the pump.
10. Rinse the vinegar from the water heater as follows:
a. Remove the free end of the drain hose (H3) from
the pail. Place in sink or outside to drain.
b. Close service valve, (V2), and open shuto valve,
(V4). Do not open shuto valve, (V3).
c. Allow water to ow through the water heater for
5 minutes.
d. Close shuto valve (V4). When unit has nished
draining remove the in-line lter at the cold water
inlet and clean out any residue. Place lter back
into unit and open valve (V4).
e. Close service valve, (V1), and open shuto valve,
(V3).
Flushing the Heat Exchanger
11. Disconnect all hose
12. Restore electrical power to the
water heater.
Following ush procedure call
technical assistance (1-800-621-
9419) for PCB reset informaon.
11 of 17

If the water heater is not going to be used during a period of possible freezing weather, it is recommended that
the water inside the water heater be drained.
Manual Draining of the Water Heater
Running a low volume of water through the water heater to prevent freezing
If the temperature exceeds the ability of the water heater to freeze protect
itself, or if power is lost, the following steps may prevent the water heater
and external piping from freezing. (Units connected with EZ Connect (2
unit link) should be drained to prevent freezing if not in use.)
1. Turn the water heater o.
2. Close the gas supply valve.
3. Turn on a hot water tap to ow water about 0.1 gal/min or where the
stream is about 0.2 inches thick.
When the water heater or external piping has frozen
1. Do not operate the water heater if it or the external piping is frozen.
2. Close the gas and water valves and turn o the power.
3. Wait unl the water thaws. Check by opening the water supply valve.
4. Check the water heater and the piping for leaks.
HOT
COLD
ON!
0.1 gal/min or
about 0.2 inch
thick
To avoid burns, wait unl the equipment cools down before draining the water. The
water in the appliance will remain hot aer it is turned o.
WARNING
To manually drain the water:
1. Shut o cold water supply and gas supply.
2. Turn o the temperature controller.
3. Disconnect the power to the water heater.
4. Place a container to catch the water. Open hot water tap or
open hot water drain plug at the hot water outlet.
5. Remove water lter to drain the cold water.
6. Unscrew the water drain plug from the drain line next to the hot
water outlet.
7. Remove the condensate trap drain plug and allow to drain.
To resume normal operaon:
1. Conrm that all water drain plugs are removed, that the gas
supply is turned o, and that all taps are closed.
2. Insert the condensate trap drain plug.
3. Screw in the water drain plugs. (Avoid over ghtening)
4. Screw in the water lter in the cold water inlet.
5. Open the cold water supply.
6. Open a tap and conrm that water ows, and then close.
7. Turn on the power.
8. Aer conrming that the temperature controller is o, turn on the gas supply.
9. Turn on the temperature controller.
Water
drain plug
Condensate
trap drain plug
Condensate
drain line
Gas
connecon
Cold water
inlet
Hot water
outlet
12 of 17

State Regulaons
NOTICE BEFORE INSTALLATION This direct-vent appliance must be installed by a licensed professional. If you are not
properly trained, you must not install this unit.
IMPORTANT: In the State of Massachuses (248 CMR 4.00 & 5.00)
For all side wall horizontally vented gas fueled equipment installed in every dwelling, building or structure used in
whole or in part for residenal purposes, including those owned or operated by the Commonwealth and where the side wall
exhaust vent terminaon is less than seven (7) feet above nished grade in the area of the venng, including but not limited
to decks and porches, the following requirements shall be sased:
1. INSTALLATION OF CARBON MONOXIDE DETECTORS. At the me of installaon of the side wall horizontal vented gas
fueled equipment, the installing plumber or gaser shall observe that a hard wired carbon monoxide detector with an
alarm and baery back-up is installed on the oor level where the gas equipment is to be installed. In addion, the
installing plumber or gaser shall observe that a baery operated or hard wired carbon monoxide detector with an
alarm is installed on each addional level of the dwelling, building or structure served by the side wall horizontal vented
gas fueled equipment. It shall be the responsibility of the property owner to secure the services of qualied licensed
professionals for the installaon of hard wired carbon monoxide detectors
a. In the event that the side wall horizontally vented gas fueled equipment is installed in a crawl space or an ac, the
hard wired carbon monoxide detector with alarm and baery back-up may be installed on the next adjacent oor
level.
b. In the event that the requirements of this subdivision can not be met at the me of compleon of installaon, the
owner shall have a period of thirty (30) days to comply with the above requirements; provided, however, that during
said thirty (30) day period, a baery operated carbon monoxide detector with an alarm shall be installed.
2. APPROVED CARBON MONOXIDE DETECTORS. Each carbon monoxide detector as required in accordance with the above
provisions shall comply with NFPA 720 and be ANSI/UL 2034 listed and IAS cered.
3. SIGNAGE. A metal or plasc idencaon plate shall be permanently mounted to the exterior of the building at a
minimum height of eight (8) feet above grade directly in line with the exhaust vent terminal for the horizontally vented
gas fueled heang appliance or equipment. The sign shall read, in print size no less than one-half (1/2) inch in size, "GAS
VENT DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS".
4. INSPECTION. The state or local gas inspector of the side wall horizontally vented gas fueled equipment shall not
approve the installaon unless, upon inspecon, the inspector observes carbon monoxide detectors and signage
installed in accordance with the provisions of 248 CMR 5.08(2)(a)1 through 4.
13 of 17

Replacement Parts
Tech Sheet
Item No.
Gas Control Assembly 100
Electrode / Flame Rod Kit 116, 117
Fan Assembly / Motor 125
Heat Exchanger 143
Secondary Heat Exchanger 160
Water Flow Servo & Sensor 401
Bypass-Servo Assembly 403
Water Filter Assy 412
PC Board 700
An Frost Unit 701
Ignitor 706
Thermal Fuse Harness 725
Ignitor Thermal Fuse Harness
Bypass-Servo Assembly Water Filter Assy
PC Board An Frost Unit
Water Flow Servo &
Sensor
Heat Exchanger
Fan Assembly / Motor
Gas Control Assembly Electrode / Flame Rod
The Technical Sheet that is located inside the front
cover of the water heater contains a complete
illustrated parts list.
Secondary Heat
Exchanger
14 of 17

Limited Warranty for Ultra Series RUC80i, RUC90i, RUC98i, RU80e,
RU90e, RU98e
What is covered?
The Rinnai Standard Limited Warranty covers any defects in materials or workmanship when the product is
installed and operated according to Rinnai wrien installaon instrucons, subject to the terms within this Limited
Warranty document. This Limited Warranty applies only to products that are installed correctly. Improper
installaon may void this Limited Warranty. In order for this warranty to apply, it is required that you use a licensed
professional who has aended a Rinnai installaon training class before installing this water heater. This Limited
Warranty coverage as set out in the table below extends to the original purchaser and subsequent owners, but only
while the product remains at the site of the original installaon. This Limited Warranty only extends to the rst /
original installaon of the product and terminates if the product is moved or reinstalled at a new locaon.
How long does warranty coverage last?
[1] Period of coverage is reduced to 3 years from date of purchase when used as a recirculang water heater within a
hot water recirculaon loop, where the water heater is in series with a recirculaon system and all recirculang
water ows through the water heater, and where an aquastat / thermostat, mer, or an on-demand recirculaon
system is not incorporated.
[2] The Rinnai Limited Warranty for a heat exchanger used in a recirculaon system which is controlled through an
aquastat / thermostat, or mer, or an on-demand system is 12 years for residenal applicaons and 5 years for
commercial applicaons.
[3] Period of coverage is reduced to 5 years from date of purchase if the Rinnai water heater temperature seng
exceeds 160° F (71° C).
[4] Labor coverage is extended to 5 years in residenal applicaons and to 2 years in commercial applicaons if the
product is registered within 30 days (except registraon is not required in California and Quebec) and/or if the
other condions above in the Residenal Applicaons and Commercial Applicaons secons are sased.
NOTE: The integrated controller on indoor models has a 1 year warranty on parts.
What will Rinnai do?
Rinnai will repair or replace the covered product or any part or component that is defecve in materials or
workmanship as set forth in the above table. Rinnai will pay reasonable labor charges associated with the repair or
replacement of any such part or component during the term of the labor warranty period. All repair parts must be
genuine Rinnai parts. All repairs or replacements must be performed by a licensed professional that is properly
trained, state qualified or licensed to do the type of repair.
Replacement of the product may be authorized by Rinnai only at its sole discretion. Rinnai does not authorize any
person or company to assume for it any obligation or liability in connection with the replacement of the product. If
Rinnai determines that repair of a product is not possible, Rinnai may replace the product with a comparable
product at Rinnai’s sole discretion. The warranty claim for product parts and labor may be denied if a component or
product returned to Rinnai is found to be free of defects in material or workmanship; damaged by improper
installation, use or operation; or damaged during return shipping.
Item
Period of Coverage (from date of purchase)
Residenal Applicaons If used for both residenal water
heang and space heang purposes Commercial Applicaons
Heat Exchanger 12 years [1] [2] [3] 10 years [1] [3] 5 years [1] [2]
All Other Parts and Components 5 years [1] 5 years [1] 5 years [1]
Reasonable Labor 1 year [4] 1 year [4] 1 year [4]
15 of 17

How do I get service?
You must contact a licensed professional for the repair of a product under this Limited Warranty. For the name of a
licensed professional please contact your place of purchase, visit the Rinnai website (www.rinnai.us), call Rinnai at
1-800-621-9419 or write to Rinnai at 103 Internaonal Drive, Peachtree City, Georgia 30269.
Proof of purchase is required to obtain warranty service. You may show proof of purchase with a dated sales receipt,
or by registering within 30 days of purchasing the product. To register your tankless water heater, please visit
www.rinnai.us. For those without internet access, please call 1-866-RINNAI1 (746-6241). Receipt of Registraon by
Rinnai will constute proof-of-purchase for this product. Registraon of product installed in new home construcon
may be veried with a copy of the closing papers provided by the inial home buyer. However, Registraon is not
necessary in order to validate this Limited Warranty.
What is not covered?
This Limited Warranty does not cover any failures or
operang dicules due to the following:
accident, abuse, or misuse
alteraon of the product or any component part
misapplicaon of this product
improper installaon (such as but not limited to)
product being installed in a corrosive environment
condensate damage
improper venng
incorrect gas type
incorrect gas or water pressure
absence of a drain pan under the appliance
water quality
improper maintenance (such as but not limited to scale
build-up, freeze damage, or vent blockage)
incorrect sizing
any other cause not due to defects in materials or
workmanship
problems or damage due to res, ooding, electrical
surges, freezing or any acts of God.
force majeure
There is no warranty coverage on product installed in a
closed loop applicaon, commonly associated with space
heang only applicaons.
Use of an MCC-91-2 controller in a residenal dwelling will reduce the warranty coverage to that of a commercial
warranty applicaon except when an MCC-91-2 is used with a hydronic air handler for temperatures no higher than
160°F (71°C).
This Limited Warranty does not apply to any product whose serial number or manufacture date has been defaced.
This Limited Warranty does not cover any product used in an applicaon that uses chemically treated water such as a
pool or spa heater.
Limitaon on Warranes
No one is authorized to make any other warranes on behalf of Rinnai America Corporaon. Except as expressly
provided herein, there are no other warranes, expressed or implied, including, but not limited to warranes of
merchantability or tness for a parcular purpose, which extend beyond the descripon of the warranty herein.
Any implied warranes of merchantability and tness arising under state law are limited in duraon to the period of
coverage provided by this Limited Warranty, unless the period provided by state law is less. Some states do not allow
limitaons on how long an implied Limited Warranty lasts, so the above limitaon may not apply to you.
Rinnai shall not be liable for indirect, incidental, special, consequenal or other similar damages that may arise,
including lost prots, damage to person or property, loss of use, inconvenience, or liability arising from improper
installaon, service or use. Some states do not allow the exclusion or limitaon of incidental or consequenal
damages, so the above limitaon may not apply to you.
This Limited Warranty gives you specic legal rights, and you may also have other rights which vary from state to state.
www.rinnai.us/warranty
16 of 17

EXTEND THE LABOR COVERAGE UNDER YOUR LIMITED WARRANTY*
Ultra Series RUC80i, RUC90i, RUC98i, RU80e, RU90e, RU98e
REGISTRATION REQUIRED*
Rinnai is providing the opportunity to extend your Rinnai Standard Limited Warranty on labor only on Ultra Series models
RU80, RU90, RU98, RUC80, RUC90, and RUC98 if you register within 30 days of purchase of your unit. Products not registered
will sll be covered under the Rinnai standard product limited warranty as provided in the Installaon and Operaon
Instrucon manual which comes with this product. Warranty informaon is also available on Rinnai's web site at
www.rinnai.us.
RESIDENTIAL APPLICATIONS:
The limited warranty period on the labor coverage for models RUC80i, RUC90i, RUC98i, RU80e, RU90e and RU98e
Tankless Water Heaters installed in a residenal applicaon is extended for an addional 48 months (a total of 60 months
labor coverage from date of purchase), when used in a residenal hot water applicaon, if the product is registered within
30 days of purchase at www.rinnai.us/product-registraon or by calling 1-866-RINNAI-1 (746-6241), except registraon is
not required in California and Quebec.
ADDITIONAL CONDITIONS OF EXTENDING THE LABOR COVERAGE UNDER THE LIMITED WARRANTY:
1. The labor coverage does NOT extend if the RUC80i, RUC90i, RUC98i, RU80e, RU90e, and RU98e Tankless Water Heater is used
for structure heang or in a closed loop applicaon.
2. If the product is installed on a circulaon system, the circulaon system must be controlled through an aquastat / thermostat,
or mer, or an on-demand system, or the limited warranty will not be extended.
COMMERCIAL APPLICATIONS:
The limited warranty period on the labor coverage for models RUC80i, RUC90i, RUC98i, RU80e, RU90e, and
RU98e Tankless Water Heaters installed in a commercial applicaon is extended for an addional 12 months (a
total of 24 months labor coverage from date of purchase), when used in a commercial hot water applicaon, if
the product is registered within 30 days of purchase at www.rinnai.us/product-registraon or by calling 1-866-
RINNAI-1 (746-6241), except registraon is not required in California and Quebec.
ADDITIONAL CONDITIONS OF EXTENDING THE LABOR COVERAGE UNDER THE LIMITED WARRANTY:
1. The labor coverage does NOT extend if the RU80, RU90, RU98, RUC80, RUC90, and RUC98 Tankless Water Heater is used for
structure heang or in a closed loop applicaon.
2. If the product is installed on a circulaon system, the circulaon system must be controlled through an aquastat / thermostat,
or mer, or an on-demand system, or the limited warranty will not be extended.
*Only applicable if product is registered within 30 days of purchase and the other condions are met. Note
to California and Quebec Residents, and residents of other jurisdicons that prohibit warranty benets
condioned on registraon, registraon is not required to obtain longer warranty periods and failure to
register does not diminish your warranty rights. www.rinnai.us/warranty
17 of 17
Rev. 08/2014