Rinnai Circ-Logic RU98i User manual

1Rinnai CVent
Common Vent Installaon Manual
For the RU98i (REU-KB3237FFUD-US) Condensing Water Heater
This manual is a supplement to the appliance manual.
Addional informaon can be obtained from the Rinnai water heater manual.
The exhaust vent system, CVent, is supplied by Ubbink.
—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
Certified to ANS Z21.10.3 - CSA 4.3
Only for U.S. installations
100000287 Version B
12/2012
This enre manual must be le for the consumer. The consumer must read and
refer to this manual for proper operaon and maintenance of the common vent system.

2Rinnai CVent
Descripon
The CVent Common Venng system provides longer vent lengths and fewer wall or roof penetraons than
convenonal single-unit venng. For the exhaust ue, CVent ulizes a CSA-cered and tested polypropylene
venng material from Ubbink, the same supplier for Rinnai's innovave line of concentric venng. The various
secons are self locking and sealing and can be pushed together without use of cement or glue.
CVent is only for use in U.S. installaons and is not currently approved for use in Canada.
Model Applicability
The common vent system is CSA cered (ANSI Z21.10.3, Gas Water Heaters Standards) for use only with the
Rinnai tankless condensing water heater RU98i (REU-KB3237FFUD-US).
Installer Qualicaons .......................................... 2
Descripon............................................................ 2
Model Applicability............................................... 2
Safety Symbols...................................................... 3
Warranty and Liability Exclusions ......................... 3
Specicaons ........................................................ 3
Parts/Kits............................................................... 4
Sample Roof Installaon....................................... 8
Sample Horizontal Terminaon Installaon………. 9
Spare Parts List………………………………………………….10
Venng Guidelines.............................................. 11
Maximum Equivalent Vent Length...................... 12
CVent Terminaon Clearances............................13
Exhaust Vent Terminaon Clearances ................14
Maintenance Clearances.....................................16
Water Heater Clearances....................................16
Installaon Instrucons.......................................17
Common Header Check valve Maintenance....... 22
Final Checklist......................................................23
Appendix
Ubbink CVent Assembly Instrucons..................24
A licensed professional must install the common
venng.
The installer should have skills such as
 connecng gas lines, water lines, valves, and
electricity
 knowledge of applicable naonal, state, and local
codes
If you lack these skills, contact a licensed professional.
Installaon is cered for sea level (0-2000 feet) only.
For installaons above 2000 feet refer to the Rinnai
Installaon and Operaon Manual for other venng
opons.
Installer Qualicaons
Table of Contents
Improper installation of the vent system and components, or failure to follow all
installation instructions, can result in serious injury.
WARNING

3Rinnai CVent
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.
This is the safety alert symbol. This symbol alerts you to potenal hazards that can kill or hurt you
and others.
DANGER
CAUTION
WARNING
Specicaons
Number of
water
heaters*
Percent
De-rated Total Btu Rate
Manifold Pressure Btu at
Minimum Rate
(without MSB)
Btu at
Minimum Rate
(with MSB)
Maximum
Rate “W.C.
Minimum
Rate “W.C.
10% 199,000 3.0 0.42 15,200
15,200
21% 394,000 3.1 0.42 30,400
31.5% 588,000 3.1 0.42 45,600
42% 780,000 3.1 0.42 60,800
52.5% 970,000 3.2 0.45 76,000
63% 1,158,000 3.2 0.45 91,200
73.5% 1,344,000 3.2 0.45 106,400
84% 1,528,000 3.2 0.45 121,600
* RU98i (REU-KB3237FFUD-US)
Altude: 0-2000 feet
Natural and propane gas
Water heaters using CVent will automacally de-rate according to the table below. Use the table below for
calculang your total Btu for mulple water heaters using CVent.
Safety Symbols
NOTE: Installaon is cered for sea level (0-2000 )
only. For installaons above 2000  refer to the
Rinnai Operaon and Installaon Manual for
other venng opons.
Claims for personal and material damages are excluded, if they are due to any or several of the following rea-
sons:
•Use of the Cvent system not in accordance with the regulaons.
•Improper assembly and incorrect operaon.
•Faulty maintenance.
•Non-compliance with the assembly and operang instrucons.
•Non-approved structural changes to the unit or to the individual components.
•Installaon of components which are not part of the Cvent system .
•Subsequent damage, which occurred through further use of the Cvent system despite known defects.
•Intenonal damage.
•Acts of God.
Warranty and Liability Exclusions

4Rinnai CVent
CVent Starter Kit
790005
8-Inch For Back–2-Back or InLine
Combustion Air & Exhaust
1
2
34
5
CVent InLine Kit
790007
8-Inch Header Kit For InLine
Combustion Air & Exhaust
15
24
36
Qty. 1
Qty. 1
Qty. 1 Qty. 1
Qty. 2
Qty. 1
Qty. 1
Qty. 1
Qty. 1Qty. 1
Qty. 1
NO QTY DESCRIPTION
11CVENT ENDPIECE (EXHAUST) W/ CLEANOUT & CONDEN-
21CVENT COMB AIR ENDPIECE D8
31CVENT CONDENSATE TRAP (32mm Connection)
41CVENT DRAIN HOSE
52CVENT DRAIN HOSE CLAMP
61UBBINK INSTALLATION INSTRUCTION
71CENTROCERIN LUBRICANT
NO QTY DESCRIPTION
11CVENT COLLECTOR, 1 CONNECTION, D8 X L20 X D4 (Exhaust)
21CVENT ELBOW D4 X 87° WITH CLEANOUT
31CVENT EXTENTION, D4 X L18
41CVENT APPLIANCE ADAPTER, CHECK VALVE AND HOSE TRAP
51CVENT COMB. AIR COLLECTOR, 1 CONNECTION, D8 X L20 X D3
61CVENT COMB AIR FLEX FITTING, D3
71CENTROCERIN LUBRICANT
Ø4” Ø3”
7
7

5Rinnai CVent
CVent Back-2-Back Kit
790008
8-Inch Header Kit For Back-2-Back
Combustion Air & Exhaust
NO QTY DESCRIPTION
11CVENT COLLECTOR, 2 CONNECTION, D8 X L20
22CVENT ELBOW D4 X 87° WITH CLEANOUT
32CVENT EXTENSION, D4 X L18
42
CVENT APPLIANCE ADAPTER WITH CHECK
VALVE AND TRAP
51CVENT COMB. AIR COLLECTOR, 2 CONNECTION,
62CVENT COMB. AIR FLEX FITTING, D3
71CENTROCERIN LUBRICANT
15
24
36
Qty. 2
Qty. 2
Qty. 2
Qty. 2
Qty. 1
Qty. 1
Ø4” Ø3”
Ø4” Ø3”
7

6Rinnai CVent
Parts / Kits
CVent Common Venng Exhaust / Intake Components (PPtl, polypropylene translucent)
Part No. Descripon Part No. Descripon
790005 CVent 8-in Starter Kit 790024 CVent 8-in Brackets
790007 CVent 8-in InLine Kit 790025 Centrocerin lubricant
790008 CVent 8-in Back-2-Back Kit 790035 CVent Extension, D4 x L18
790001 CVent 8-in Roof Terminaon Kit 790028 CVent Extension, D4 x L39
790002 CVent 8-in Flat Roof Flashing 790029 CVent Elbow D8 x 90 degree Vercal Support
790003 CVent 8-in Pitched Roof Flashing 790030 CVent 8-in Chase Cover
790004 CVent 8-in Wall Terminaon Kit 790031 CVent 8-in Vent Distancer, stainless steel
790020 CVent Extension, D8 x L18 790034 CVent 8-in Vent Rain Cap
790021 CVent Extension, D8 x L39 790032 Inverter Coupling Kit with condensate trap
790022 CVent Elbow D8 x 45degree (2 in a box) 780037 Combuson Air PVC Adapter Kit
790023 CVent Elbow D8 x 90degree
Cvent 8-in Roof Termination Kit with PVC adapter
790001
31” Ø12.2”
Ø0.24” (Qty. 4)
Interior Slip
Fit Wall Plate
Ø7.89”
Termination Kits
Cvent 8-in Wall Termination Kit (Combustion Air & Exhaust)
790004
PP-PVC
Adapter
(For Combustion Air
PVC transition)
Centrocerin
Lubricant
CVent 8-in Roof Termination
(Outer shell: Stainless Steel)
Centrocerin lubricant
(Material: Stainless Steel)

7Rinnai CVent
8 INCH VENT COMPONENTS
CVent 8-in Chase Cover
#790030
CVent Pitched Roof Flashing (Including
Storm Collar) #790003
CVent Flat Roof Flashing
#790002
CVent 8in Vent Rain Cap
#790034
Inverter Coupeling Kit With Condensate Trap
#790032
CVent Elbow D8x45 degree
#790022 (Qty.2)
CVent Elbow D8x90 degree
#790023
CVent Extension D8xL18” #790020,
D8xL39” #790021
CVent Elbow D8x90 degree
Vertical Support #790029
CVent 8-in
Bracket #790024
CVent 8in Vent
Distancer #790031
Combustion Air PVC Adapter Kit
#780037

8Rinnai CVent
CVent Extension
D4xL18 #790035
D4xL39 #790028
4 INCH VENT COMPONENTS
Sample Roof Assembly
Field Supplied
PVC Components
Field Supplied 8”
PVC Flashing
CVent 8-in Roof Termination
Kit with PVC Adapter
#790001
Cvent pitched roof moldable
flashing #790003
CVent 8-in Rain Cap
#790034
OPTIONAL
NOTE: Use PVC
adapter (illustrate
above) at the
combustion air
header when
transitioning to
PVC

9Rinnai CVent
Part Number: 790008
CVent Back-2-Back Kit (QTY. 4)
Part Number:790020 / 790021
CVent Extension (Qty. 5)
Part Number:780037
Combustion Air PVC Adapter
Kit (Qty. 1)
Part Number:790027
CVent Elbow D4 x 90
(Qty. 2)
Part Number: 790005
CVent Starter Kit (Qty. 1)
Part Number:790004
Wall Termination Kit
Combustion Air & Exhaust (Qty 2)
Field Supplied
PVC Components
Field Supplied
PVC Components
Sample Horizontal Termination Assembly

10 Rinnai CVent
Included
With Kit
No.
Part
No. Description Image
Exhaust Vent Components
790005 790042 CVent Endpiece
790005 790048 Condensate Trap (32mm Connection)
790005 790049 Hose + 2 Clamps
790007 790040 Exhaust Collector, 1 connection, D8 x L20, D4 connection
790008 790041 Exhaust Collector, 2 connections, D8 x L20, D4 connection
790007
790008 790035 CVent Extension, D4 x L18
790007
790008 790039 CVent Elbow D4 x 87degree with cleanout
Combustion Air Vent Components
790005 780046 Intake/Combustion Air Endpiece
790007 780044 Combustion Air Collector, 1 connection, D8 x L20, D3 connection
790008 780045 Combustion Air Collector, 2 connection, D8 x L20, D3 connection
790007
790008 780050 CVent flex Line D3
Appliance Adapter
790007,
790008 790038 CVent Appliance and Check Valve & hose (new!)
Spare Parts List
Ø8
Ø8
Ø8
Ø4
Ø8
Ø4
Ø4
Ø4
Ø4
Ø4
Ø3
Ø3
Ø3
Ø8
Ø3
Ø3
Ø8
Ø3

11 Rinnai CVent
Venng Guidelines
DO NOT
 Do not install in separate distribuon systems. All
water heaters common vented must be in the
same hot and cold plumbing manifolds and must
not exceed 8 units.
 Do not use PVC, CPVC, ABS or galvanized material
for the exhaust vent. CVent must be used on the
exhaust.
 Do not combine vent components from dierent
manufacturers.
 Vent diameter must not be reduced.
 Do not connect the venng system with an
exisng vent or chimney.
 Do not common vent with the vent pipe of any
other type of water heater or appliance.
 Do not install the water heater in an area of
negave pressure.
 Do not install the water heater, venng, and vent
terminaon(s) in any areas where the air may
contain corrosive compounds.
MUST DO
•The water heater dip switch seng must always
be set to long vent (#1 in set of tan switches set to
OFF).
 This water heater is a direct vent water heater and
therefore is cered and listed with the vent
system. You must use vent components that are
cered and listed with the water heater model.
 The vent system must vent directly to the outside
of the building and use outside air for combuson.
 Avoid dips or sags in horizontal vent runs by
installing supports per the vent manufacturer’s
instrucons.
 Support horizontal vent runs a minimum of every
four feet and all vercal vent runs a minimum of
every six feet.
 Venng should be as direct as possible with a
minimum number of pipe ngs.
 Vent connecons must be rmly pressed together
so that the gaskets form an air ght seal.
 Install an appliance adapter which contains a
check valve onto each water heater. Use only the
check valve specied in this manual. Do not
aempt to build your own system.
 The air intake appliance adapter connected to the
water heater must be secured with one self-
tapping screw.
 Check and clean the header check valve every 12
months according to the maintenance instrucons
in this manual.
 Set the temperature seng on all water heaters
being common vented to the same temperature.
INFORMATION
 Unless recovering a tank, Rinnai recommends
installing an MSB controller when common
venng and where water heaters are in a manifold
system.
 For assembly details, refer to the Ubbink
Installaon and Assembly Instrucons located in
the appendix of this manual.
 Rinnai recommends replacing the check valve
when replacing the water heater.
The Ubbink Polypropylene CVent can be used on both the combustion air and exhaust.
Field supplied PVC material can only be used on the combustion air side and MUST NOT
be used for the exhaust.
WARNING

12 Rinnai CVent
Vercal Terminaon
Maximum Equivalent Vent Length
Number of water
heaters
Minimum Equivalent Vent Length Maximum Equivalent Vent Length
Exhaust* Intake* Exhaust* Intake*
1 to 7 5  15  100  100 
85  15  41  41 
In the table below you nd the maximum equivalent pipe
length of the exhaust and intake venng.
When determining equivalent exhaust and intake vent
lengths add:
•6 feet for each 90° elbow
•3 feet for each 45° elbow
There should be a minimum of 36 inches between
exhaust terminaons in mulple common vent
installaons.
CVent Terminaon Clearances
•Add any vent extension lengths which are
added within the header due to increased
spacing of the water heaters
•Header kits have already been counted and
do not need to be added.
Clearances of Brackets
All supports such as wall brackets on the
external façade or spacer blocks in a
shaft must be assembled in a maximum
distance of 78 in (2 m). Where there is a
bend, additional spacer blocks or wall
brackets can be planned before and after
the bend, depending on the local
situation.
Freestanding Components
Components, which are assembled
freestanding vertical (roof termination)
with a length of more than 59 in (1.5 m),
must, depending on the amount of wind
and snow level expected, be additionally
secured to the building with guys or
braces.
*Approved exhaust and intake diameter is 8 inches.
12” OVER MAX.
SNOW LEVEL OR
24” WHICHEVER
IS GREATER
INTAKE - PVC
EXHAUST - CVent
36” MINIMUM INSIDE
EDGE TO INSIDE EDGE

13 Rinnai CVent
CVent Terminaon Clearances
This appliance along with the CVent Common Vent System is cered with the Cvent 8-in Wall Terminaon Kit,
(790004) mounted in the orientaon shown below.
Horizontal Terminaon
The exhaust and combustion air terminations must
follow these clearances:
[1] 12 inch minimum vertically from bottom of exhaust
termination to top of intake termination.
[2] 12 inch minimum vertically from bottom of
combustion air termination to ground or anticipated
snow line.
[3] From edge of exhaust termination to edge of
combustion air termination:
Minimum of 36 inches
Maximum of 20 feet
[4] 36 inch minimum from multiple exhaust CVents
There should be a minimum of 36 inches between
exhaust terminations in multiple common vent
installations.
The vent (exhaust & combustion air) terminations must
be in the same pressure zone and face the same
direction.
NOTE: During colder weather when the exhaust tem-
perature is much hotter than the outside air, the
exhaust fumes condense producing water va-
por. As a result a plume of water vapor may be
seen leaving the exhaust.
Vertically
Vertically
MAXIMUM 20’
MINIMUM 36”
EXHAUST
VENT
COMBUSTION
AIR
VENT
Combustion
Air Vent
Combustion
Air Vent

14 Rinnai CVent
Exhaust Vent Terminaon Clearances
INSIDE
CORNERDETAIL
FIXED
CLOSED
OPERABLE
FIXED
CLOSED
OPERABLE
B
B
B
A
J
BM
C
F
B
B
E
D
L
G
A
H
K
I
[1] A vent shall not terminate directly above a sidewalk or paved
driveway that is located between two single family dwellings and
serves both dwellings.
[2] Permitted only if veranda, porch, deck, or balcony is fully open on
a minimum of two sides beneath the floor.
 For clearances not specified in ANSI Z223.1/NFPA 54, clearances
are in accordance with local installation codes and the requirements
of the gas supplier.
Clearance to opposite wall is 24 inches (60 cm).
X
V
AIR SUPPLY INLET
VENT TERMINAL
AREA WHERE
TERMINAL IS NOT
PERMITTTED
For indoor models, you must install terminaons to bring in combuson air and expel exhaust.
Ref Description US Installations
AClearance above grade, veranda, porch, deck, or balcony 12 inches (30 cm)
BClearance to window or door that may be opened 12 inches (30 cm)
CClearance to permanently closed window *
D
Vertical clearance to ventilated soffit, located above the terminal
within a horizontal distance of 2 feet (61 cm) from the center line
of the terminal
*
EClearance to unventilated soffit *
FClearance to outside corner *
GClearance to inside corner *
HClearance to each side of center line extended above meter/
regulator assembly *
IClearance to service regulator vent outlet *
JClearance to nonmechanical air supply inlet to building or the
combustion air inlet to any other appliance 12 inches (30 cm)
KClearance to a mechanical air supply inlet 3 feet (91 cm) above if within 10
feet (3 m) horizontally
LClearance above paved sidewalk or paved driveway located on
public property
Refer to local code for horizontal
termination above a public
walkway, driveway, or area where
condensate or vapor could create
a nuisance or hazard.
MClearance under veranda, porch, deck, or balcony *
SNOW
TERMINATION
Clearance in
Ref. A also
applies to
anticipated
snow line

15 Rinnai CVent
Check on whether local codes supersede these clearances.
 Avoid terminaon locaons near a dryer vent.
 Avoid terminaon locaons near commercial
cooking exhaust.
 You must install a vent terminaon at least 12
inches above grade or snow line.
60"
V
V
(0.91 m)
between
terminals at
dierent levels
24"
V
(0.61 m) to wall or parapet
(0.91 m) between
terminals at same
level
Addional clearances
36"
24"
INS ID E
CO RNER
V V
(0.61 m ) to an inside corner
(0.91 m) between
terminals at same
level
The vent for this appliance shall not terminate
•Over public walkways; or
•Near sot vents or crawl space vents or other
area where condensate or vapor could create a
nuisance or hazard or cause property damage; or
•Where condensate or vapor could cause damage
or could be detrimental to the operaon of
regulators, relief valves, or other equipment.
Important consideraons for locang vent
terminaon under a sot (venlated or unvenlated
or eave vent; or to a deck or porch)
 Do not install vent terminaon under a sot vent
such that exhaust can enter the sot vent
 Install vent terminaon such that exhaust and
rising moisture will not collect under
eaves. Discoloraon to the exterior of the
building could occur if installed too close.
 Do not install the vent terminaon too close
under the sot where it could present
recirculaon of exhaust gases back into the
combuson air intake part of the terminaon.
VRepresents the exhaust vent of CVent
common venng.
36”
36”

16 Rinnai CVent
Water Heater Clearances
Indoor
model
RU98i
to
Combustibles
inches (mm)
to Non-
Combustibles
inches (mm)
Top of Heater 6 * (152) 2 *(51)
Back of Heater 0 (zero) 0 (zero)
Front of Heater 6 (152) 6 (152)
Sides of Heater 2 (51) 1/2 (13)
Ground/Bottom 12 (305) 12 (305)
Vent 0 (zero) 0 (zero)
* 0 inches from vent components and condensate drain line.
The clearance for servicing is 24 inches in front of the water
heater.
to side
to front
to top
to floor/ground
Maintenance Clearances
Back to Back Conguraon In Line Conguraon
Follow the recommended minimum service clearances below for maintenance access to the header above the
water heater.
If the vent system is to be enclosed, it is suggested that the design of the enclosure shall permit inspection of the
vent system. The design of such enclosure shall be deemed acceptable by the installer or the local inspector.
Follow the minimum clearances from the water heater.
5.15”
42”
36”
30”
42”

17 Rinnai CVent
Installaon Instrucons
Exhaust Vent Installaon Procedures:
•Aer ensuring the water heaters are mounted securely and
spaced 20.5” apart, install the appliance adapter on top of
the water heaters.
•Exhaust Venng is designed for a 3° rise. When the water
heaters are mounted at 20.5” spacing, the height increase is
1” per water heater. A 4” diameter extension pipe is
included with the kit that must be cut to length to account
for the rise from unit to unit. Aer cung, always deburr and
bevel the end of the vent piece so the sealing gaskets are not
damaged and operaon of the vent system is not
compromised.
•Install the elbows with hand cleanout cap to the 4” diameter
extension pipe. Do not cut or modify the elbow. Cleanout cap
should remain accessible for periodic inspecon and access
for service when needed.
•Aer combuson air and exhaust vent components are
appropriately posioned, securely fasten the “CVent
Appliance Adapter with Check Valve and Trap” to the top of
the water heater with a self tapping screw.
•Connect the combuson air opening of the appliance adapter
to one end of the ex connector and the other end of the ex
connector to the Combuson Air Collector.
•Connect the open end of the elbow to the exhaust header.
Securing Screw
Elbow
hand cleanout cap
4” Extension
Appliance
Adapter
Combustion Air Collector
Flex Connector
Elbow
Exhaust Collector

18 Rinnai CVent
Opons for Combuson Air Vent:
•For extended Intake pipe runs, PVC can be used between the Intake Header and Terminaon.
•Use the PVC adapter (described below) when transioning from the PP intake header to the stainless steel
Combuson Air Terminaon.
•Combuson Air PVC Adapter Kit (Part #: 780037) includes both a transion from the 8” (200mm) PP header
to 8” PVC and an 8”PVC to 8” (200mm) terminaon
•Fasten, secure, and support all vent materials using manufacturer and industry standards to avoid potenal
intake air leaks or blockage. Support horizontal vent runs a minimum of every 4 feet and all vercal vent
runs a minimum of every 6 feet.
The materials described below can only be used on the combustion air vent. The Ubbink
Polypropylene CVent can be used on both the combustion air and exhaust. Field supplied
PVC material can only be used on the combustion air side and MUST NOT be used for
the exhaust.
WARNING
Approval Codes for In-
stallaon
Item Descripon Flue Material United States
Plasc Vent and/or
combuson air
components
PVC Schedule 40 ANSI/ASTM D1785
PVC - DWV ANSI/ASTM D2665
CPVC Schedule 40 ANSI/ASTM F441
Plasc pipe cement
and primer
PVC ANSI/ASTM D2564
CPVC ANSI/ASTM F493
FIELD
SUPPLIED
PVC PIPE
Plasc pipe
cement and
primer
PVC to TERMINATION ADAPTER:
8”PVC to 8” (200mm) terminaon
PP to PVC ADAPTER:
8” (200mm) PP header to 8” PVC

19 Rinnai CVent
Installaon Instrucons
Back to back Conguraon (2 to 8 water heaters)
In Line Conguraon (2 to 8 water heaters)
Refer to the Ubbink appendix of this manual for the vent system assembly instrucons.
Follow these Rinnai installaon instrucons in this manual in addion to the Ubbink vent system assembly
instrucons.
Install the venng according to one of the 2 conguraons below. Do not locate the common vent remotely
from the water heaters.
The installaon area should be measured to make sure that adequate space is available to install the water
heaters and venng system.
NOTE: Dimensions above
are used in all back to back
configurations
Note: If water heaters are mounted directly on a wall, air intake piping will need to be in front of the appliance
adapters. The intake header in the drawing above has been removed for illustraon purposes.
TYPICAL
20.5” (520)
3°
1”
(25mm)
2”
(51mm)
3”
(76mm)
EXHAUST
AIR
INTAKE
7”
(178mm)
6.25”
(159mm)
1”
(25mm)
2”
(51mm)
3”
(76mm)
3°
4”
(101mm)
5”
(127mm)
6”
(152mm)
7”
(178mm)
TYPICAL
20.5” (520)
AIR
INTAKE
EXHAUST

20 Rinnai CVent
Installaon Instrucons
Recommended Spacing of Water Heaters
Spacing of the water heaters is crical for the common vent
system to mounng easily and securely. The collectors are
made for 20.5” spacing (center line to center line) between
water heaters. If a dierent spacing is needed, please
contact Rinnai concerning your applicaon. Rinnai
recommends using our Tankless Rack System (TRS) which is
designed for 20.5” spacing. Our engineered system is
designed to make installaon simple which greatly reduces
labor me and the chance of miscalculaons.
Custom Water Heater Spacing
If common venng with LESS than 20.5” between water heaters:
•The installer assumes all responsibility of following local codes. Inspectors can reject the installaon if the
rang plate cannot be seen for all water heaters.
•D4 Extension Pieces must be cut appropriately to maintain the required 3° slope.
If common venng with GREATER than 20.5” between water heaters:
•The installer must purchase a vent extension cut to the appropriate length between the collectors.
•The length of each addional vent extension must be considered in the maximum allowable vent length.
•D4 Extension Pieces must be cut appropriately to maintain the required 3° slope.
NOTE: Never attempt to cut or modify the
collectors.
To maintain a 3° slope, use the following
formula to calculate D4 Extension Piece
length (L):
(L) = (water heater spacing) X 0.05
Example: if the adjacent water heater is
20.5” away
Length (L) = 20.5” x 0.05 = 1.02”
Example: if the adjacent water heater is
26” away
Length (L) = 26.0” x 0.05 = 1.30”
20.5 in
Vent extension -
cut to size
Air Intake -
extension
D4 Extension
Piece