Rinnai RH180 Specification sheet

— Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other
appliance.
— WHAT TO DO IF YOU SMELL GAS
x Do not try to light any appliance.
x Do not touch any electrical switch; do not use any phone in your building.
x Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instrucons.
x If you cannot reach your gas supplier, call the fire department.
— Installaon and service must be performed by a licensed professional.
This enre manual must be lefor the consumer. The consumer must read and
refer to this manual for proper operaon and to maintain the water heater.
If the informaon in these instrucons is not followed exactly, a fire or explosion
may result causing property damage, personal injury or death.
WARNING
READ ALL OF THE INSTRUCTIONS THOROUGHLY BEFORE INSTALLING OR OPERATING THIS WATER HEATER.
This manual provides informaon on the installaon, operaon, and maintenance of the water heater. For proper operaon and
safety, it is important to follow the instrucons and adhere to the safety precauons.
A licensed professional must install the water heater according to the exact instrucons on pages 4-30.
The consumer must read the enre manual to properly operate the water heater and to have regular maintenance performed.
Operaon and Installaon Manual
RH180 (REU-VA1320WF-US)
Automac Circulang Tank Water Heater
(Chauffe-eau àcirculaƟon automaƟque )
FOR INDOOR APPLICATIONS ONLY
Hybrid Tank-Tankless Water Heater
ANSI Z21.10.3 ●CSA 4.3-(2011)
— Ne pas entreposer ni uliser d'essence ou ni d'autres vapeurs ou liquids inflammables à proximité de
cet appareil ou de tout autre appareil.
— QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE GAZ :
• Ne pas tenter d'allumer d'appareil.
• Ne touchez à aucun interrupteur ; ne pas vous servir des téléphones se trouvant dans le bâƟment.
• Appelez immédiatement votre fournisseur de gaz depuis un voisin. Suivez les instrucƟons du
fournisseur.
• Si vous ne pouvez rejoindre le fournisseur, appelez le service des incendies.
—L'installaon et l'entreen doivent être assurés par un installateur ou un service d'entreen qualifié ou
par le fournisseur
Assurez-vous de bien suivre les instrucons données dans cee
noce pour réduire au minimum le risque d'incendie ou d'explosion
ou pour éviter tout dommage matériel, toute blessure ou la mort.
AVERTISSEMENT

2 RH180 Manual
Table of Contents
This is the safety alert symbol. This symbol alerts you to potenal hazards that can kill or hurt you
and others.
Indicates an imminently hazardous situaon which, if not avoided, will result in death or
serious injury.
Indicates a potenally hazardous situaon which, if not avoided, could result in death or
serious injury.
Indicates a potenally hazardous situaon which, if not avoided, could result in minor or
moderate injury. It may also be used to alert against unsafe pracces.
DANGER
CAUTION
WARNING
Safety Definions
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/
oryouaccountwithus.
If you have any quesons or feel that the manual is incomplete contact Rinnai at 1-800-621-9419.
Safety Definions............................................. 2
Safety Behaviors and Pracces
for the Consumer and Installer ...................... 3-5
Installaon Instrucons
Installer Qualificaons .....................................6
General Instrucons.........................................6
Determine Installaon Locaon.......................8
Installaon Locaon.........................................9
Checklist to Determine Locaon....................10
Minimum Clearances .....................................11
Typical Installaon Illustraon.......................12
Combuson Air Requirements................. 13-15
Venng Requirements ............................. 16-19
Checklist for Combuson Air
and Venng ...................................................20
Installaon of Plumbing .................................21
Checklist for Plumbing ...................................22
Massachuses-Required Plumbing ...............23
Installaon of Gas Supply......................... 24-25
Connect Electricity .........................................26
Adjust for High Altude .................................26
Checklist for Gas and Electricity .................... 26
Final Checklist ................................................ 27
Technical Data
Specificaons ................................................. 28
Dimensions .................................................... 29
Wire Diagram................................................. 30
Parts Breakdown............................................ 31
Operaon
Consumer Operaon Guidelines
for the Safe Operaon of
your Water Heater ......................................... 32
How to use the Temperature Controller ....... 33
Diagnosc Codes and Remedies ...............35-36
Required Maintenance
Air Screen....................................................... 37
Water Filter.................................................... 38
Required Maintenance .............................. 39-40
Consumer Support
Warranty Registraon Informaon ............... 41
Limited Warranty......................................41-43

RH180 Manual 3
Safety Behaviors and Pracces for the Consumer and Installer
x Before operang, smell all around the appliance area
for gas. Be sure to smell next to the floor because
some gas is heavier than air and will sele on the
floor.
x Keep the area around the appliance clear and free
from combusble materials, gasoline, and other
flammable vapors and liquids.
x Combusble construcon refers to adjacent walls and
ceiling and should not be confused with combusble
or flammable products and materials. Combusble
and/or flammable products and materials should
never be stored in the vicinity of this or any gas
appliance.
x Always check the water temperature before entering
a shower or bath.
x To protect yourself from harm, before performing
maintenance:
¡ Turn offthe electrical power supply by unplugging
the power cord or by turning offthe electricity at
the circuit breaker. (The temperature controller
does not control the electrical power.)
¡ Turn offthe gas at the manual gas valve, usually
located adjacent to the water heater.
¡ Turn offthe incoming water supply. This can be
done at the cold water supply valve immediately
below the water heater or by turning offthe
water supply to the building.
x Cauon: Label all wires prior to disconnecon when
servicing controls. Wiring errors can cause improper
and dangerous operaon.
(Aenon: Au moment de l’entreen des commandes,
équetez tous les fils avant de les débrancher. Des
erreurs de câblage peuvant entraîner un
fonconnement inadequate et dangereux.)
x Verify proper operaon aer servicing.
(S’assurer que l’appareil fonconne adequate une fois
l’entreen terminé.)
x 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 fire or explosion.
WARNING
x Do not use this appliance if any part has been under
water. Immediately call a qualified service technician
to inspect the appliance and to replace any part of the
control system and any gas control which has been
under water.
(N’ulisez cet appareil s’il alimentaon a été plunge
dans l’eau, meme parellement. Faites inspecter
l’appareil par un technician qualifié et remplacez toute
pare du système de contrôle et toute commande qui
ont été plongés dans l’eau.)
x Do not use substute parts that are not authorized for
this appliance.
x Should overheang occur or the gas supply fail to shut
off, turn offthe manual gas control valve to the
appliance.
(En cas de surchauffe ou si l’alimentaon en gaz ne
s’arrête pas, fermez manuellement le robinet d’arrêt
de l’admission de gaz.)
x Do not adjust the DIP switch unless specifically
instructed to do so.
x Do not use an extension cord or an adapter plug with
this appliance.
x Any alteraon to the appliance or its controls can be
dangerous and will void the warranty.
x Make sure the water heater and its water lines are
protected from freezing. Damage due to freezing is
not covered by the warranty.
x Suitable for combinaon water (potable) heang and
space heang and not suitable for space heang
applicaons only.
(Convient au chauffage combiné de l’eau (potable) et
des locaux, mais non au chauffage des locaux
seulement.)
x This appliance must be installed in accordance with
local codes, the Naonal Fuel Gas Code,
ANSI Z223.1 / NFPA 54 or the CSA B149.1, Natural Gas
and Propane Installaon Code.
(Cet appareil doit être installé selon les réglements
locaux, ou en l’absence de tells réglements, selon le
Naonal Fuel Gas Code, ANSI Z223.1/NFPA 54, ou les,
Code d’installaon du gaz natural et du propane, CSA-
B149.1.)
x WARNING—Follow instrucons for proper installaon.
(AVERTISSMENT—Suivre les instrucons pour une
installaon appropriée.)

4 RH180 Manual
FLAMMABLE
(INFLAMMABLE)
Flammable Vapors
(Les Vapeurs Inflammables)
WARNING
DANGER Hot water can be dangerous, especially for infants or children, the elderly,
or infirm. There is hot water scald potenal if the thermostat is set too
high.
Water temperatures over 125º F (51º C) can cause severe burns or
scalding resulng in death.
Hot water can cause first degree burns with exposure for as lile as:
3 seconds at 140º F (60º C)
20 seconds at 130º F (54º C)
8 minutes at 120º F (48º C)
Test the temperature of the water before placing a child in the bath or
shower.
Safety Behaviors and Pracces for the Consumer and Installer
CAUTION
x BURN HAZARD. Hot exhaust and vent may cause
serious burns. Keep away from water heater unit.
Keep small children and animals away from unit.
x Hot water outlet pipes leaving the unit can be hot
to touch. In residenal applicaons, insulaon
must be used for hot water pipes below 36” due to
burn risk to children.
California law requires this noce to be provided:
California Proposion 65 lists chemical substances known to the state to cause cancer, birth defects, death,
serious illness or other reproducve harm. This product may contain such substances, be their origin from fuel
combuson (gas, oil) or components of the product itself.
FOR YOUR SAFETY
Do not store or use gasoline or other
flammable vapors and liquids in the vicinity
of this or any other appliance
POUR VOTRE SECURITE
Ne pas entreposer ni ulizer d’essence ni
d’autres vapeurs ou liquids inflammables à
proximité de cet appareil ou de tout autre
appareil.
CAUTION
Hoer water increases the risk of scald injury. Before
changing temperature seng, see instrucon manual.
ATTENTION
De l’eau plus chaude augmente le risqué de brûlure.
Voir la noce d’instrucons avant de modifier le
réglage de la temperature.
AVERTISSEMENT

RH180 Manual 5
Safety Behaviors and Pracces for the Consumer and Installer
FVIR (Flammable Vapor Ignion Resistant) Sensor
Flammable liquids such as cleaning solvents, aerosols, paint thinners, adhesives, gasoline and propane must be
handled and stored with extreme care. These flammable liquids emit flammable vapors and when exposed to an
ignion source can result in a fire hazard or explosion. Flammable liquids should not be used or stored in the vicinity
of this or any other appliance.
This water heater is equipped with a flammable vapor sensor and meets the requirements of ANSI Z21.10.1 If
flammable vapors are detected, the flammable vapor sensor will close the gas supply to the water heater, the ignion
source will be disabled and an “FE” error code will flash on the controller. If the controller is flashing an “FE” or if
flammable vapors are suspected:
x Leave the area immediately, leaving the exit point open to allow venlaon
x Do not touch any electric device (including phone or light switch)
x Call emergency personnel from a neighbors phone
x Do not try to reset the water heater or light the pilot to any other appliance
When safety personnel has idenfied the area as safe and all flammable vapors have been removed and eliminated
from the area, the units can be reset by unplugging the unit then plugging back in.
Do not spray or use chemicals containing bleach, cleaners, polish, silicone, phosphorous, or
lubricants near the water heater. These chemicals will damage the flammable vapor sensor.
Never clean or tamper with the flammable vapor sensor. Do not place cat lier near the
appliance as it can corrode or damage the sensor. If the sensor is corroded or damaged its
reacon me can be affected and it may not react as described.
WARNING
Install vent system per local and naonal codes.
Read and follow all instrucons in this secon.
Do not install this water heater above 5,400 (1646 m).
Do not obstruct water heater air intake.
Do not operate water heater if flood damaged.
Failure to properly vent this appliance can result in death, personal
injury and/or property damage.
Every home should have a carbon monoxide (CO) alarm in the hallway
near bedrooms in each sleeping area. Check baeries monthly and
replace them annually.
WARNING Carbon Monoxide Hazard
WARNING
x Do not use this appliance if any part has been under
water. Immediately call a qualified service technician
to inspect the appliance and to replace any part of the
control system and any gas control which has been
under water.
(N’ulisez cet appareil s’il alimentaon a été plunge
dans l’eau, meme parellement. Faites inspecter
l’appareil par un technician qualifié et remplacez
toute pare du système de contrôle et toute
commande qui ont été plongés dans l’eau.)
x Any alteraon to the appliance or its controls can be
dangerous and will void the warranty.
x This appliance is equipped with a three-prong plug for
your protecon against shock hazard and should be
plugged directly into a properly grounded three-prong
receptacle. Do not cut or remove the ground prong
from this plug.

6 RH180 Manual
A licensed professional must install the appliance,
inspect it, and leak test it before use. The warranty
will be voided due to improper installaon.
The installer should have skills such as:
x gas sizing
x connecng gas lines, water lines, valves, and
electricity
x knowledge of applicable naonal, state, and
local codes
x installing venng through a wall or roof
x Venng Category I, Fan Assist Appliances per
NFPA54 and local codes
If you lack these skills contact a licensed professional.
Installaon Instrucons
Installaon Steps
Determine Installaon Locaon ................ 8
Installaon Locaon .................................. 9
Checklist to Determine Locaon .............10
Minimum Clearances……….......................11
Typical Installaon Illustraon ................12
Combuson Air Requirements ...........13-15
Venng Requirements........................16-19
Checklist for Combuson Air
and Venng ............................................. 20
Installaon of Plumbing...........................21
Checklist for Plumbing .............................22
Massachuses-Required Plumbing .........23
Installaon of Gas Supply ...................24-25
Connect Electricity...................................26
Adjust for High Altude ........................... 26
Checklist for Gas and Electricity .............. 26
Final Checklist ..........................................27
General InstruconsInstaller Qualificaons
DO NOT
x Do not install the RH180 outdoors.
x Do not install the appliance in an area where water
leakage of the unit or connecons will result in
damage to the area adjacent to the appliance or to
lower floors of the structure. When such locaons
cannot be avoided, it is recommended that a
suitable drain pan, adequately drained, be installed
under the appliance. The pan must not restrict
combuson air flow.
x Do not obstruct the flow of combuson and
venlaon air.
x Do not use this appliance in an applicaon such as
a pool or spa heater that uses chemically treated
water . (This appliance is suitable for filling large or
whirlpool spa tubs with potable water.)
x Do not use substute parts that are not authorized
for this appliance.
MUST DO
x The installaon must conform with local codes or,
in the absence of local codes, with the Naonal
Fuel Gas Code, ANSI Z223.1/NFPA 54, or the
Natural Gas and Propane Installaon Code, CSA
B149.1.
x The appliance, when installed, must be electrically
grounded in accordance with local codes or, in the
absence of local codes, with the Naonal Electrical
Code, ANSI/NFPA 70, or the Canadian Electrical
Code, CSA C22.1.
x The appliance and its appliance main gas valve
must be disconnected from the gas supply piping
system during any pressure tesng of that system
at test pressures in excess of 1/2 psi (3.5 kPa)
(13.84 in W.C.).
x The appliance must be isolated from the gas supply
piping system by closing its individual manual
shutoffvalve during any pressure tesng of the gas
supply piping system at test pressures equal to or
less than 1/2 psi (3.5 kPa) (13.84 in W.C.).

RH180 Manual 7
Prepare for installaon
Parts included
Tools needed
Materials needed
x Make sure the water heater and its water lines are
protected from freezing. Damage due to freezing is
not covered by the warranty.
x You must follow the installaon instrucons and
those in Care and Maintenance for adequate
combuson air intake and exhaust.
x Install the vacuum relief valve per local codes.
x Massachuses 248 CMR Secon 10.14 (I) “All
potable water pressure tanks shall be provided
with a vacuum relief valve at the top of the tank
that will operate up to a maximum water pressure
of 200 P.S.I.G. and to a maximum water
temperature of 200ºF.”
INFORMATION
x If a water heater is installed in a closed water
supply system, such as one having a backflow
preventer in the cold water supply line, means
shall be provided to control thermal expansion.
Contact the water supplier or local plumbing
inspector on how to control thermal expansion.
x Should overheang occur or the gas supply fail to
shut off, turn offthe manual gas control valve to
the appliance.
x 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.
xWater heater
xTemperature-Pressure Relief (T&P) Valve
xGas Valve
xManometer
xPipe wrenches (2)
xAdjustable pliers
xScrewdrivers (2)
xWire cuers
xGloves
xSafety glasses
xLevel
Tools that might be needed
xSaw
xThreading machine with
heads and oiler
xTorch set
xCopper tubing cuer
xSteel pipe cuer
Materials that may be needed
xSoap soluon
xApproved venng
xTeflon tape
(recommended) or pipe
compound
xHeat tape
xPipe insulaon
xElectrical wire and
conduit per local code
xSingle gang electrical
box
xWire nuts
xUnions and drain valves
Vacuum Relief Valve
(Not Supplied)
If required, install per local code and
valve manufacturers instrucons

8 RH180 Manual
Environment
Air surrounding the water heater is used for
combuson and must be free of any compounds that
cause corrosion of internal components. These
include corrosive compounds that are found in
aerosol sprays, detergents, bleaches, cleaning
solvents, oil based paints/ varnishes, and refrigerants.
The air in beauty shops, dry cleaning stores, photo
processing labs, and storage areas for pool supplies
oen contains these compounds. Therefore it is
recommended that such locaons be avoided.
If it is necessary for a water heater to be located in
areas which may contain corrosive compounds, the
following instrucons are strongly recommended.
IMPORTANT CONSIDERATIONS FOR INSTALLATION:
x DO NOT Install in areas where air for combuson
can be contaminated with chemicals.
x Before installaon, consider where air has the
ability to travel within the building to the water
heater.
x Chemicals that are corrosive in nature should not
be stored or used near the water heater.
Damage and repair due to corrosive compounds in
the air is not covered by warranty.
Consideraon of care for your water heater should
include evaluaon of water quality.
Water that contains chemicals exceeding the levels
below affect 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
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
Determine Installaon Locaon
Water Quality
* Source: Part 143 Naonal Secondary Drinking Water
Regulaons
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 flushed regularly.
You must ensure that clearances will be met and that
the vent length will be within required limits.
Consider the installaon environment, water quality,
and need for freeze protecon. Requirements for the
gas line, water lines, and electrical connecon can be
found in their respecve installaon secons of this
manual.

RH180 Manual 9
Locaon
This water heater is not approved for use in manufactured (mobile) homes or outdoor installaons.
Ac:
Installaon of the water heater must be accomplished in such a manner that if the tank or any connecon should
leak, the flow of water will not cause damage to the structure. For this reason, it is not advisable to install the
water heater in an ac or upper floor. When such locaons cannot be avoided, a suitable drain pan should be
installed under the water heater. (See drain pan below)
Garage:
Although this water heater is equipped with a flammable vapor sensor, gasoline and other flammable substances
should not be stored or used in the same vicinity or area of the water heater or any other appliance that may
produce a spark or open flame.
It is not required to posion this water heater on a stand as this water heater complies with the FVIR
requirements and the burner and igniter are posioned greater than 18 inches from the base of the unit.
This water heater must be posioned or located as to not be subject to damage by a moving vehicle.
Refer to local code for installaon requirements in a garage.
Crawl Space:
When installing this water heater in a crawl space with a dirt floor, posion the water heater on a solid concrete
plaorm, or base to avoid damage to the unit. (Do not use wood)
Drain Pan: If the water heater is installed in a locaon that could result in damage to the home or structure
precauons must be taken to protect the property from water damage. In the event of a tank or component
failure, an appropriately sized pan must be installed under the water heater. The pan must drain with a
minimum diameter ¾” connecon and shall be drained per local code requirements.
Stand: Depending on local code, a stand may not be required due to the ignion source being over 18” from
the base of the appliance.
Alcove or closet:
See clearance requirements and combuson air requirements.
Insulaon Blanket:
This water heater meets or exceeds the Naonal Appliance Energy Conservaon Act standards with respect to
insulaon and standby losses. If an insulaon blanket is sll desired, the following procedure must be followed.
a. Maintain an adequate distance from the vent.
b. Do not cover the front door of the tankless engine or the lower enclosure of the assembly.
c. Do not cover the combuson air grill located on the front door of the tankless engine.
d. Do not obstruct the operaon of the pressure relief valve.
e. Obtain new warning labels from the manufacturer to place on the blanket, directly over the exisng
labels.
f. Frequently inspect the blanket to ensure the insulaon blanket has not been disturbed.

10 RH180 Manual
Checklist to Determine Installaon
Locaon
□The water heater is not exposed to corrosive
compounds in the air.
□The water heater locaon complies with the
clearances stated in the manual and on the label,
located on the side of the unit.
□The area surrounding the water heater does not
contain flammable vapors that could ignite.
□The water supply does not contain chemicals or
exceed total hardness that will damage the heat
exchanger.
□The water heater and its water lines are protected
from freezing.
□A standard 3 prong 120 VAC, 60 Hz properly
grounded wall outlet or other properly grounded
120 VAC, 60 Hz source is available.
□The installaon must conform with local codes or,
in the absence of local codes, with the Naonal
Fuel Gas Code, ANSI Z223.1/NFPA 54, or the
Natural Gas and Propane Installaon Code, CSA
B149.1.
□Leave the enre manual taped to the water
heater or give the enre manual directly to the
consumer.

RH180 Manual 11
Minimum Clearances
The minimum clearances from combusbles or non-combusbles construcon, 0 inches from the sides, 0 inches
from the back, and 12 inches from the top.
For closet installaon, 4 inches front, or for alcove installaon
(Dégagements minimaux à assurer entre les parois de l’appareil et les construcons incombusbles: 0 po (côtés),
0 po (arriè) et 12 po (dessus).)
(Installaon dans une garde-robe: assurer un dégagement de 4 po devant l’appareil. Pour installaon dans une
alcôve.)
0” Min 0” Min
0” Min
4” Min
12” Min
Clearance to be in accordance with local installaon codes and the requirements of the gas supplier.
(Dégagement conforme aux codes d’installaon locaux et aux exigencies due foumisseunde gaz.)

12 RH180 Manual
A Hot Water Outlet *
B Hot Water Outlet Valve *
C Temperature-Pressure Relief
Valve
D Cold and Hot Unions *
E Cold Water Supply Valve *
F Cold Water Supply *
G Thermal Expansion Tank *
H 4” B-Vent *
I Combuson Air Screen
J Operaon Unit / Temperature
Control
K Outlet Receptacle *
L Drain Pan *
M Temperature-Pressure Relief
Valve Discharge Pipe
(do not cap, plug, or reduce )
*
N Drip Leg (Sediment Trap) *
O Gas Union *
P Gas Control Valve
Q Thermostac Mixing Valve *
R Non-Tempered Return Line *
S Non-Tempered Supply Line *
Typical Installaons
*Field Supplied
A B D
C
E F
H
P
O
N
J
I
K
G
M
L
S
F
R
Q A
MIXING VALVE INSTALLATION
RETURN
SUPPLY
COLD WATER
SUPPLY
NON-TEMPERED
SUPPLY
COLD WATER
SUPPLY
HOT WATER
OUTLET

RH180 Manual 13
CombusonAirRequirements
This water heater requires adequate combuson air for venlaon and diluon of flue gases. Failure to provide
adequate combuson air can result in unit failure, fire, explosion, serious bodily injury or death. Use the
following methods to ensure adequate combuson air is available for correct and safe operaon of this water
heater.
Important: Combuson air must be free of corrosive chemicals. Do not provide combuson air from corrosive
environments. Appliance failure due to corrosive air is not covered by warranty.
Combuson air must be free of acid forming chemical such as sulfur, fluorine and chlorine. These chemicals have
been found to cause rapid damage and decay and can become toxic when used as combuson air in gas
appliances. Such chemicals can be found in, but not limited to bleach, ammonia, cat lier, aerosol sprays,
cleaning solvents, varnish, paint and air fresheners. Do not store these products or similar products in the
vicinity of this water heater.
Unconfined Space:
An unconfined space is defined in Naonal Fuel Gas Code, ANSI Z223.1/NFPA 54 as “a space whose volume is not
less than 50 cubic feet per 1000 Btu/hr (4.8 m3 per kW per hour) of the aggregate input rang of all appliances
installed in that space. Rooms communicang directly with the space in which the appliances are installed,
through openings not furnished with doors, are considered a part of the unconfined space.” If the “unconfined
space” containing the appliance(s) is in a building with ght construcon, addional outside air may be required
for proper operaon. Outside air openings should be sized the same as for a confined space.
Unconfined Space Unconfined Space
91,300 BTU Water Heater and a
100,000 BTU Furnace
(7.6m)
(7.6m)
(10.6m)

14 RH180 Manual
Combuson air provided to the appliance
should not be taken from any area of the
structure that may produce a negave pres-
sure (i.e. exhaust fans, powered venlaon
fans).
Confined Space:
(Small Room, Closet, Alcove, Ulity Room, Etc.)
A confined space is defined in the Naonal Fuel Gas
Code, ANSI Z223.1/NFPA 54 as "a space whose
volume is less than 50 cubic feet per 1000 Btu/hr (4.8
m3 per kW per hour) of the aggregate input rang of
all appliances installed in that space." A confined
space must have two combuson air openings. Size
the combuson air openings based on the BTU input
for all gas ulizaon equipment in the space and the
method by which combuson air is supplied:
Louvers and Grills
When sizing the permanent opening as illustrated in
Figure 1, consideraon must be taken for the design
of the louvers or grills to maintain the required free
area required for all gas ulizing equipment in the
space. If the free area of the louver or grill design is
not available, assume wood louvers will have 25%
free area and metal louvers or grills will have 75% free
area. Under no circumstance should the louver, grill
or screen have openings smaller than ¼”.
Example:
Wood: 10 in x 12 in x 0.25 = 30 in2
Metal: 10 in x 12 in x 0.75 = 90 in2
Locaon
To maintain proper circulaon of combuson air two
permanent openings (one upper, one lower) must be
posioned in confined spaces. The upper shall be
within 12 inches of the confined space and the lower
opening shall be within 12 inches of the boom of the
confined space. Openings must be posioned as to
never be obstructed.
Using Outdoor Air For Combuson
Outdoor air can be provided to a confined space
CombusonAirRequirements
Figure 1

RH180 Manual 15
When communicang indirectly with the outdoors
through vercal ducts, each opening shall have a
minimum free area of 1 in2/4000 Btu/hr (550 mm2/
kW) of total input rang of all appliances in the
confined space. Combuson air to the appliance can
be provided from a well venlated ac or crawl
space.
CombusonAirRequirements
through two permanent openings, one commencing within 12 in. (300mm) of the top and one commencing
within 12” (300mm) of the boom, of the confined space. The openings shall communicate to the outside by
one of two ways:
When communicang directly with the outdoors
through horizontal ducts, each opening shall have a
minimum free area of 1 in2/2000 Btu/hr (1100 mm2/
kW) of total input rang of all appliances in the
confined space.
Note: If ducts are used, the cross seconal area of
the duct must be greater than or equal to the
required free area of the openings to which they are
connected.
Using Indoor Air For Combuson
When using air from other room(s) in the building, the total volume of the room(s) must be of adequate volume
(Greater than 50 cubic feet per 1000 Btu/hr). Each Combuson air opening must have at least one square inch
of free area for each 1000 Btuh, but not less than 100 square inches each.
Directly through horizontal ducts Indirectly through vercal ducts

16 RH180 Manual
Venng
This water heater must be vented vercally to the
outside of the building or structure.
This water heater is not designed or cerfied for side
wall horizontal vent terminaons.
All installaons must be vented in accordance with
Naonal Fuel Gas Code, ANSI Z223.1/NFPA 54 - latest
edion and the requirements of state or local codes.
In Canada, the furnaces must be vented in accordance
with the Naonal Standard of Canada, CAN/CSA
B149.1 and CAN/CSA B149.2 - latest edions and
amendments and the codes of the local ulity or
other authority having jurisdicon.
NOTE: The vercal height of the Category I venng
system must be at least as great as the horizontal
length of the venng system.
VenngRequirements
Screw
Vent Pipe (4” diameter)
Screw Screw
WARNING
TO PREVENT POSSIBLE PERSONAL INJURY OR DEATH
DUE TO ASPHYXIATION,
COMMON VENTING WITH OTHER MANUFACTURER’S
INDUCED DRAFT APPLIANCES IS NOT ALLOWED.
WARNING
Devices aached to the vent system intended to
increase system efficiency by reducing the heat loss of
the vent system MUST not be used on this water
heater. Rinnai accepts no liability for damage or injury
if such devices are installed on the vent system with
this appliance.
WARNING
Vent Pipe Assembly: To avoid damage to the vent and
vent adapter, pre drill holes with a 1/8” drill bit.
Aach the vent to the vent adapter with #8 screws.
x All vent (Category I) passing through a concealed
space, an ac or floor, MUST be Type B double wall
vent and/or Type B double wall vent connectors. For
vent passing through an interior wall, use Type B vent
with venlated thimble ONLY.
x The RH180 CANNOT be vented into any chimney
serving an open fireplace or any other solid fuel
burning appliance.
x Use the same diameter Category I connector or vent as
permied by NFPA 54/ANSI Z223.1 venng tables.
x It is not permied to reduce vent diameter (4”).
x It is emphasized that vercal Category I vent or vent
connector runs be as short and direct as possible.
x Vercal outdoor runs of type B or ANY single wall vent
below the roof line are NOT permied.
x All horizontal vent runs to be sloped up away from the
RH180 a minimum of ¼” (6mm) per foot.
x All horizontal vent runs are to be supported, at a
minimum, every 6' (2m) using suitable clamps and/or
metal straps.
x Exisng gas vent or chimney is to be checked to ensure
they meet clearances and local codes.
The RH180 can ONLY be connected to a manufactured
chimney or vent that complies with a recognized
standard. Venng into a masonry or concrete chimney
is only permied as outlined in the NFPA 54/ANSI
Z223.1 Naonal Fuel Gas Code venng tables. It is
therefore a contractual obligaon on the part of the
installer to follow all safe venng requirements.
Poison carbon monoxide gas hazard.
If this appliance is replacing a previously common
vented water heater, it may be necessary to resize
the exisng chimney liner or vent to prevent over siz-
ing problems for the other remaining appliance
(s). See codes and/or standard having jurisdicon.
Failure to properly vent this water heang appliance
or other appliance(s) can result in death, personal
injury and/or property damage.
WARNING

RH180 Manual 17
VenngRequirements
Vent Dampers
Vent dampers must be cerfied in accordance with ANSI Z21.68
Before installing any flue damper, consult the local gas authority and damper manufacturer for proper
installaon.
Vent Inspecon
The enre vent system (Combuson air ducts, louvers etc., and exhaust vent) must be checked periodically for
signs of obstrucon or damage. If damaged components are observed they must be repaired or replaced
immediately.
Vent Size
This water heater is equipped with a 4” vent adapter and must never be aached to a vent smaller than 4”.
Certain applicaons may require vent diameters greater than 4” Consult your local gas supplier or authority to
aid in the proper vent diameter selecon per the requirements of the vent tables in the current edion of the
Naonal Fuel Gas Code ANSI Z223.1/NFPA 54.
Vent Connectors
Vent Connectors are relavely short runs of vent connecng the appliance to the chimney or vercal vent run.
Following is a list of appropriate vent connector material for use between the water heater and the chimney:
x Type B (B-Vent) Double wall, U.L. listed vent pipe
x Type B (B-Vent) Single wall, U.L. listed vent pipe
Note the following when installing a vent connector from the appliance to the chimney or vercal vent:
Length: A vent connector shall be as short as praccal and the appliance located as close as praccal to the
chimney or vent. The maximum horizontal length of the vent connector cannot exceed 75% of the
height of the chimney or vent. Unnecessary bends should be avoided as to not create excessive
resistance to flow of vent gases.
Prohibited locaons: Vent Connectors cannot pass through any ceiling, floor, firewall, or fire paron.
CHIMNEY
OR
LISTED VENT
MIN. ¼ inch rise
per foot
Vent Connector
Single wall vent connectors: A single wall vent
connector must not pass through any interior
walls, floors or ceilings. A single wall vent
connector must not be installed in acs, crawl
spaces or any other confined space or inaccessible
locaon. Maintain a minimum of 6” from
combusbles when using single walled vent
connectors.
Double Walled, B-Vent: It is acceptable to pass
through walls or parons with double walled, B-
Vent.
Slope: Vent connectors must pitch ¼ inch per foot
(21mm per meter) upward.
WARNING
Thermal Operated Vent Dampers: Should NOT be used with this appliance. This appliance has a thermal efficien-
cy greater than 80%. This higher efficiency will result in lower flue gas temperatures. Such temperatures may be
too low to acvate a thermal operated vent damper. Use of a thermal operated flue damper on this product may
result in spillage of exhaust gases and ulmately carbon monoxide poisoning.

18 RH180 Manual
Vent Terminaon
All flue (Vent) gases must be directed to the outdoors of the building or structure and must not terminate
horizontally.
VenngRequirements
Lowest discharge opening
Listed
Listed
Roof pitch is x/12
H (minimum) –
Minimum height from
Figure 2
x
12
Roof Slope H (minimum)
m
Flat to 6/12 1.0 0.30
Over 6/12 to 7/12 1.25 0.38
Over 7/12 to 8/12 1.5 0.46
Over 8/12 to 9/12 2.0 0.61
Over 9/12 to 10/12 2.5 0.76
Over 10/12 to 11/12 3.25 0.99
Over 11/12 to 12/12 4.0 1.22
Over 12/12 to 14/12 5.0 1.52
Over 14/12 to 16/12 6.0 1.83
Over 16/12 to 18/12 7.0 2.13
Over 18/12 to 20/12 7.5 2.27
Over 20/12 to 21/12 8.0 2.44
The vent terminaon shall comply with the following requirements:
If the gas vent is 12 inches (300mm) or less in diameter and located not less than 8 (2.4m) from a vercal
wall or similar obstrucon, the terminaon must comply with the requirements stated in Table 1 and Figure
2. If the gas vent is greater than 12 inches in diameter or located less than 8 (2.4m) from a vercal wall or
similar obstrucon, the terminaon must end not less than 2 (0.6m) above any poron of a building within
10(3.0m) horizontally.
B-Vent type gas vent shall terminate at least 5 (1.5m) in vercal height above the highest connected
appliance drahood or flue collar.
Decorave shrouds or coverings shall not be installed over the gas vent terminaon unless listed for use with
the specific gas vent and are installed in accordance with the manufacturer’s installaon instrucons.
All gas vents shall extend through the roof flashing, roof jack, or roof thimble and terminate with a listed cap
or listed roof assembly.
The gas vent shall terminate at least 3 (0.9m) above any forced air inlet located within 10 (3.0m)
Table 1
Inspecon: The enre length of the vent connector shall be readily accessible for inspecon, cleaning and
replacement.
Joints: Must be fastened by sheet metal screws or other approved methods.
Support: Vent connectors must be supported per the vent manufacturer’s installaon instrucons to avoid
dips or sags in the vent and maintain the required clearances.

RH180 Manual 19
VenngRequirements
Masonry Vercal Venng
Masonry Chimneys shall be built and installed in accordance with NFPA 211, Standard for Chimneys, fireplaces,
Vents and Solid Fuel-Burning Appliances.
Before assembling the vent connector to a chimney, the chimney must be inspected for signs of obstrucon or
damage. If previously used for solid or liquid fuel burning appliances or fireplaces, the chimney must be cleaned.
Do not connect the vent of this water heater to a chimney servicing a separate solid fuel burning appliance.
Do not connect the vent of this water heater to a le lined masonry chimney. The chimney must be lined with
either B-Vent or a listed chimney lining system.
Connecon to a chimney must be firmly aached, sealed and must be located above the extreme boom of the
chimney.
B-Vent Vercal Venng
Vercal gas vent must be installed with U.L. listed type B-vent material in accordance with the manufacturer’s
installaon instrucons and the requirements stated in the “Naonal Fuel Gas Code”, NFPA 54, ANSI Z223.1-
latest edion and the requirements of local codes.
Vent should extend in a generally vercal direcon. Any vent angle less than 45 degrees is considered horizontal.
The total horizontal distance of the vent system plus the horizontal length of the vent connector must not
exceed 75 percent of the vercal height of the vent.
An unused chimney or masonry enclosure may be used as a chase for the installaon of listed B-vent material.
Common Venng
As a Category I appliance, this water heater can be vented vercally with type B-1 vent systems and lined
masonry chimneys. Follow the Naonal Fuel Gas Code, ANSI Z223.1 and or the Naonal Gas Installaon code,
CSA-B149.1 & .2 for proper installaon pracces. If you are unsure or need assistance in correct applicaon of a
common vent installaon consult the local gas authority for assistance in the vent system design.

20 RH180 Manual
Checklist for Combuson Air and
Venng Requirements
□Verify proper clearances around the vents .
□Ensure that the Combuson Air Requirements are
followed that will provide sufficient combuson
air for the appliance.
□Ensure you have used the correct venng
products for Category 1 and that you have
completely followed the venng manufacturer’s
installaon instrucons and these installaon
instrucons. All installaons must be vented in
accordance with Naonal Fuel Gas Code NFPA
54/ANSI Z223.1 - latest edion and the
requirements of state or local codes. In Canada,
the furnaces must be vented in accordance with
the Naonal Standard of Canada, CAN/CSA
B149.1 and CAN/CSA B149.2 - latest edions and
amendments and the codes of the local ulity or
other authority having jurisdicon.
□All horizontal vent runs must be sloped up away
from the water heater a minimum of 1/4 “ (6 mm)
per foot.
□Verify that the vent terminaon clearances are
followed.
□Verify that there is adequate combuson air.