Bosch C950ES User manual

C 950 ES
INDOOR MODEL
Temperature Modulated with Electronic Ignition
Suitable for heating potable water and space heating
(Intended for variable flow applications)
C 950 ES - Natural Gas
C 950 ES - Liquefied Petroleum (LP) Gas
6 720 646 812 (2011/05) US
Warning: If the information in this manual is not
followed exactly, a fire or explosion may result
causing property damage, personal injury or death.
Do not store or use gasoline or other flammable
vapors and liquids in the vicinity of this or any other
appliance.
Improper installation, adjustment, alteration,
service or maintenance can cause injury or
property damage. Refer to this manual. For
assistance or additional information consult a
qualified installer, service agency or the gas
supplier.
In the Commonwealth of Massachusetts this
product must be installed by a licensed plumber or
gas fitter.
Upon completion of the installation, these
instructions should be handed to the user of the
appliance for future reference.
What to do if you smell gas
• Close gas valve. Open windows.
• 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 instructions.
• If you cannot reach your gas supplier, call the fire
department.
• Installation and service must be performed by a
qualified installer, service agency or the gas supplier.

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2
Index
Index
1 Warning 3
2 Appliance details 5
2.1 Features 5
2.2 Specifications (Technical data) 5
2.3 Unpacking the heater 6
2.4 General rules to follow for safe operation 8
2.5 Dimensions and minimum
installation clearances 9
3 Installation instructions 10
3.1 Specialized tools 10
3.2 Introduction 10
3.3 Venting 10
3.4 Combustion air requirements 24
3.5 Proper location for installing your heater 25
3.6 Heater placement and clearances 25
3.7 Mounting installation 25
3.8 Gas piping & connections 26
3.9 Water connections 29
3.10 Water quality 29
3.11 Filling the condensate trap 31
3.12 Domestic hot water recirculation 32
3.13 Space heating applications 33
3.14 Measuring gas pressure 35
4 Electrical connections 36
4.1 Electrical power supply 36
4.2 Position of the fuses in control unit 36
5 Operation instructions 37
5.1 Description LCD Display 37
5.2 For your safety read before operating
your water heater 38
5.3 Power 38
5.4 Temperature selection 38
5.5 Use of optional remote control accessory
(part no. TSTAT2) 39
5.6 Operation 39
5.7 Reset button 39
5.8 Program button 40
5.9 Locked condition 40
6 Maintenance and service 41
6.1 Annual maintenance 41
6.2 Winterizing for seasonal use 41
6.3 Mineral scale build-up 42
6.4 Condensing heat exchanger unit 42
6.5 Adjusting CO2 43
6.6 Program values 45
6.7 Control board diagnostics 46
7 Troubleshooting 47
7.1 Introduction 47
7.2 Burner does not ignite when hot
water is turned ON 47
7.3 Water is too hot 47
7.4 Water is not hot enough 47
7.5 Low water flow/pressure 48
7.6 Hot water temperature fluctuates at tap 48
7.7 Noisy burner/heater during operation 48
8 Problem solving 49
8.1 Error code diagnostics 49
9 Electrical diagram 53
10 Sensor resistance charts 54
11 Functional scheme 56
12 Interior components diagram
and parts list 57
12.1 Interior components 57
12.2 Components diagram 59
13 Protecting the environment 66
14 LIFETIME LIMITED WARRANTY
FOR BOSCH PRO TANKLESS
WATER HEATERS 67
15 Notes 69

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Warning
3
1 Warning
For your safety
Do not store or use gasoline or other flammable,
combustible or corrosive vapors and liquids in the
vicinity of this or any other appliance.
Warning: Carefully plan where you
install the heater. Correct combustion
air supply and flue pipe installation are
very important. If a gas appliance is not
installed correctly, fatal accidents can
result such as carbon monoxide
poisoning or fire.
Warning: Exhaust gas must be vented
to outside using approved vent material
See table 2, page 10 (For Canada use
only ULCS636 approved material).
Vent and combustion air connector
piping must be sealed gas-tight to
prevent possibility of flue gas spillage,
carbon monoxide emissions and risk of
fire, resulting in severe personal injury
or death. Approved vent terminators
must be used when penetrating to the
outside.
Warning: Place the heater in a location
where water leaks will do NO DAMAGE
to adjacent areas or lower floors.
Warning: Field wiring connections and
electrical grounding must comply with
local codes, or in the absence of local
codes, with the latest edition of the
National Electric Code, ANSI/NFPA 70,
or in Canada, all electrical wiring must
comply with the local codes and the
Canadian Electrical Code, CSA C22.1
Part 1.
Warning: Shock hazard: line voltage is
present. Before servicing the water
heater, unplug power supply cord from
outlet. Failure to do so could result in
severe personal injury or death.
Warning: The heater must be
disconnected from the gas supply
piping system during any pressure
testing of that system at test pressures
equal to or more than 0.5 psig.
Warning: The appliance should be
located in an area where leakage of the
heater or connections will not result in
damage to the area adjacent to the
appliance or to lower floors of the
structure. When such locations cannot
be avoided, it is recommended that a
suitable drain pan, adequately drained,
be installed under the appliance. The
pan must not restrict combustion air
flow.
Warning: The maximum inlet gas
pressure must not exceed the value
specified by the manufacturer and the
minimum value listed is for the purpose
of input adjustment.
Warning: 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
this situation.
Warning: Keeping appliance area clear
and free from combustible materials,
gasoline and other flammable vapors
and liquids.
Warning: Do not obstruct the flow of
combustion and ventilation air.
Warning: Precautions must be taken
prior to manually operating the relief
valve to avoid contact with hot water
coming out of the relief valve and to
prevent water damage.
Caution: Label all wires prior to
disconnection when servicing controls.
Wiring errors can result in improper and
dangerous operation.
Verify proper operation after servicing.

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Warning
FCC:
This device complies with Part 15 of the FCC rules.
Operation is subject to the following two conditions: (1)
This device may not cause harmful interference, and (2)
this device must accept any interference received,
including interference that may cause undesired opera-
tion.
Fig. 1
Warning: If a relief valve discharges
periodically, this may be due to thermal
expansion in a closed water supply
system. Contact the water supplier or
local plumbing inspector on how to
correct this situation. Do not plug the
relief valve.
Warning: If the water heater is used in
a space heating application, all piping
and components connected to the
water heater must be suitable for use
with potable water.
Warning: Toxic chemicals, such such
as those used for boiler treatment, shall
not be introduced into the potable water
used for space heating.
Warning: A water heater which will be
used to supply potable water shall not
be connected to any heating system or
component(s) previously used with a
nonpotable water heating appliance.
HOT
BURN
D A N G E R
Water temperature over 125°F can
cause severe burns instantly or
death from scalds.
Children, disabled and elderly are
at highest risk of being scalded.
See instruction manual before
setting temperature at water
heater.
Feel water before bathing or
showering.
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Appliance details
5
2 Appliance details
2.1 Features
Parts
• Key Pad interface control
• High power pre-mix compact burner with low NOx
emissions
• Modulating Gas Valve with constant gas:air ratio
control
• Modulating water valve for improved comfort and
temperature control.
High quality materials for long working life
• Copper heat exchanger
• High efficiency Ceramat Burner
• Compact space saver: mounts on a wall with a
supplied bracket.
Features
• Easily removable one-piece cover
• On/Off and Temperature control switches
• Reset button
• Program button (Selectable temperature default)
• Failure codes for easy diagnostics and repair
• Real-time diagnostics for troubleshooting/informa-
tional purposes
• Built in freeze prevention.
Note: The freeze prevention kit is designed to provide
protection for the water heater down to approximately
5°F for short term conditions only. It will not protect the
appliance in areas where the temperature is routinely
expected to be below freezing.
- The freeze prevention kit will not protect plumbing out-
side the appliance from freezing. Precautions should be
taken.
Accessories (Bosch part #)
• Optional wireless remote control to operate with the
appliance (TSTAT2)
• Cascading kit (77090003962)
• Outdoor kit (BTOK)
• External water filter (part # 8 703 305 356)
• Concentric termination kit (196016)
• Exhaust/Intake bird screen (L2594)
• Condensate drain tee (196061) [included with Con-
centric termination kit]
• Pipe Cover (PTPCES)
• High temperature kit (7736500074)
• Recess box kit (7736500043)
• Pressure relief valve (FWL-2).
2.2 Specifications (Technical data)
Approved in US/Canada
Capacity
Maximum flow rate: 7.15 GPM (27 l/min) at a 45°F
(25°C) rise.
Maximum output
157,700 Btu/h (46.2 kW)
Maximum input
175,000 Btu/h (51.2 kW)
Efficiency in %
Thermal efficiency > 92%
Minimum Input
19,900 Btu/h (5.8 kW)
Temperature Control
Selection range: 100°F (38°C) - 140°F (60°C)
Default temperature: 122°F (50°C)
Stability: +/- 2°F (+/- 1°C)
Gas Requirement
Gas connection (inches) - ¾”
Inlet gas pressure under operation (with a high hot
water flow rate)*
• Propane: 8” - 13” water column
• Natural Gas: 3.5” - 10.5” water column.
* To measure Gas Pressure, see Measuring Gas
Pressure, chapter 3.14, page 35.
Water
• Hot water connection (inches) - ¾”
• Cold water connection (inches) - ¾”
• Water valve material: Polymer (PPS) (Polypropylene
Sulfid)
• Minimum water flow: 0.5 gallon/minute (1.9 l/m)
Note: Activation varies with inlet water temperatures
from 0.5 - 1.6 gallon/minute (1.9 - 6.1 l/m).
• Minimum recommended water pressure: 30 PSI
(2.07 bar)
• Minimum well pressure 40 psi, see page 29.
• Connections:
– Bottom of heater
Combustion
• NOx ≤14 Ng/J
(Nanograms of NOx (calculated as NO2) per
Joule of heat output).
i
BOSCH is constantly improving its
products, therefore specifications are
subject to change without prior notice.

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6
Appliance details
• CO ≤290 ppm (measured)
• CO
2
level set from factory, see chapter 6.5, page 43.
Dimensions
• Depth (in): 11¼” (286 mm)
• Width (in): 17
7
/
8
” (452 mm)
• Height (in): 30½” (775 mm)
• Weight: 74 pounds (33.5 kg).
Gas types
Natural Gas.
LP Gas.
Voltage
120 V AC (60 Hz) nominal
Amperage
Idle - 40 mA
Operation - ≤2.5 A
Noise
45 - 65 db (A)
Safety devices
• Flame failure device (ionization flame rod sensor)
• Overheat prevention (temperature limiter)
• Inlet temperature sensor
• Outlet temperature sensor
• Back flow temperature sensor
• Exhaust gas temperature sensor.
Water protection
IP X4 (protection against water drops)
2.3 Unpacking the heater
Before installing the unit, be certain you have the
correct heater for your type of Gas - Propane or
Natural Gas. Identification labels are found on the
shipping box, and on the rating plate which is located on
the right side panel of the cover.
Fig. 2 Rating plate
ASerial number
BType of gas
The box includes:
• C 950 ES
• Bracket for wall hanging the heater
• Exhaust vent adaptor (with 4 screws and gasket
provided)
• Combustion air inlet adaptor (with 3 screws and gas-
ket provided)
• Installation manual (manual can be downloaded at
www.bosch-climate.us)
• Product registration card
• Energy Guide label.
Please complete and return the enclosed product
registration card.
The C 950 ES is not approved or designed for:
•Manufactured (mobile) homes, boats or any
mobile installation. (Modular homes are
acceptable for installation).
•Use above 8000 ft A.S.L. altitude (see page 21).
•Outdoor installation without installation of
Outdoor kit (BTOK).
• Applications where inlet water temperature is
higher than 140°F (60°C). A 3-way valve or
mixing valve must be installed before the
appliance if inlet water temperature exceeds
this limit.
i
If appliance is installed at elevations above
2000ft, refer to Section 3.3.7 Fan speed
adjustment.

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Appliance details
7
To remove front cover
BLoosen the two Phillips head screws located on
bottom rear of cover (see Fig. 3).
Fig. 3 Loosen the two screws
BLift front cover panel upward and remove.
Fig. 4 Remove the front cover
To remove combustion cover (service only)
BOpen the four clips and remove the combustion
cover (see Fig. 5).
Fig. 5 Remove the combustion cover
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Appliance details
2.4 General rules to follow for safe
operation
B1. You must follow these instructions when you
install your heater. In the United States: The
installation must conform with local codes or, in the
absence of local codes, the National Fuel Gas Code
ANSI Z223.1/NFPA 54.
In Canada: The Installation must conform with CSA
B149.(1,2) INSTALLATION CODES and /or local
installation codes.
B2. Carefully plan where you install the heater. Correct
combustion air supply and vent pipe installation are
very important. If not installed correctly, fatal
accidents can occur, such as carbon monoxide
poisoning or fire.
B3. When the unit is installed indoors and ROOM
SEALED (twin pipe) it is permitted to be located in
bathrooms, bedrooms and occupied rooms that are
normally kept closed. See chapter 3.3 (page 10). If
the unit will be installed indoors and use indoor
combustion air, the place where you install the heater
must have enough ventilation. The National Fuel
Gas Codes do not allow UNSEALED gas fired
water heater installations in bathrooms,
bedrooms or any occupied rooms normally
kept closed. See chapter 3.4 (page 24).
B4. You must correctly vent your heater. See
chapter 3.3 (page 10) on VENTING.
B5. The appliance and its gas connection must be leak
tested before placing the appliance in operation.
The appliance must be isolated from the gas supply
piping system by closing its individual manual gas
shutoff valve (not supplied with heater) during any
pressure testing at pressures in excess of ½ Psig
(3.5 kPa).
B6. Keep water heater area clear and free from
combustibles and flammable liquids. Do not locate
the heater over any material which might burn.
B7. Correct gas pressure is critical for the proper
operation of this heater. Gas piping must be sized to
provide the required pressure at the maximum output
of the heater, while all the other gas appliances are in
operation. Check with your local gas supplier, and
see the section on connecting the gas supply. See
chapter 3.8 (page 26).
B8. Should overheating occur or the gas supply fail to
shut off, turn off the gas supply at the manual gas
shut off valve, on the gas line. Note: manual gas
shutoff valve is not supplied with the heater but must
be field installed.
B9. Do not use this appliance if any part has been
underwater. 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 underwater.
B10. Failure to install heater correctly may lead to
unsafe operation and void the warranty.

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Appliance details
9
2.5 Dimensions and minimum installation clearances
Fig. 6 Dimensions
1On/Off button
2Reset button
3Program key
4Power ON or stand-by LED
5LCD display
6Up button
7Down button
Fig. 7 Minimum clearances
Note: For servicing access, a 2ft clearance is
recommended to the front cover.
6720608000-03.2AL
6
4
Model C 950 ES
TOP (A) 12”
FRONT (B) 1”
BACK 0”
SIDES 1”
FLOOR (C) 12”
Table 1 Minimum clearances

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Installation instructions
3 Installation instructions
3.1 Specialized tools
The following specialized tools may be required for
installation:
• Manometer
• Multi-meter
• Combustion Gas Analyzer.
3.2 Introduction
Please follow these instructions. Failure to follow
instructions may result in:
BDamage or injury.
BImproper operation.
BLoss of warranty.
3.3 Venting
3.3.1 Vent material
All combustion air and vent pipe materials and fittings
must comply with the following:
For specific questions concerning vent material,
specifications, usage or installation, please
contact the vent manufacturer directly.
All vent connections must be glued, except for the
exhaust accessory (see section 3.3.4) which is
screwed into place on the top of the appliance. Slide
the vent pipe into the exhaust accessory. The exhaust
pipe must be properly supported and must be pitched
a minimum of a ¼ inch per foot back to the appliance.
This allows the condensate to drain properly.
An optional concentric vent/air intake termination can
be used for the installation of a vertical or horizontal
venting system. (see Fig. 8).
The concentric vent/air intake body can be ordered
from your local wholesaler. (Part# 196016).
The appliance can also be installed with separate air
intake and exhaust piping (see Fig. 11, Fig. 18 and Fig.
19, page 18).
Warning: The water heater must be
installed by a qualified installer in
accordance with these instructions. If
improperly installed, a hazardous condition
such as explosion or carbon monoxide
poisoning could result. Bosch
Thermotechnology Corp. is not
responsible for improperly installed
appliances.
i
Common installation practice is to
first determine the venting/
combustion air point of termination,
then design the piping layout back to
the heater.
Warning:
BDo not reduce the exhaust or
combustion air vent pipe sizes.
BDo not common vent with any other
vented appliance or stove.
BDo not use Type-B vent as the actual
exhaust vent system for the appliance.
Warning: Failure to vent the exhaust
gases to the outside (see Table 2 for
proper material) may result in
dangerous flue gases filling the
structure in which it is installed.
Warning: In areas where outside
temperatures routinely come close to
freezing, sealed combustion operation
is required. Concentric termination or
separate terminations for combustion
and vent, must be installed on the same
wall or roof surface; however, never
facing the direction of prevailing winds.
Failure to do so may result in heat
exchanger freezing and bursting. This
failure is not covered under the
manufacturer's warranty.
Warning: Protect the exhaust and inlet
from leaves and debris by installing a
screen on the end of the terminator.
¼" mesh minimum opening
recommended on screen.
Item Material United States Canada
Vent or
air pipe
and
fitting
PVC schedule 40 ANSI/ASTM D1785
CSA or ULC
certified only
(ULC-S636)
PVC-DWV ANSI/ASTM D2665
CPVC schedule 40 ANSI/ASTM F441
ABS-DWV schedule 40 ANSI/ASTM D2661
Pipe
cement /
primer
PVC ANSI/ASTM D2564
CPVC ANSI/ASTM F493
ABS ANSI/ASTM D2235
Table 2 Approved vent material
i
Do not use cellular foam core pipe.

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Installation instructions
11
Fig. 8 Concentric vent kit example
3.3.2 Vent specifications
Establish vent clearances that comply with the vent
manufacturer's specifications and all applicable
national/local codes.
Venting specifications
*ULC S636-95, UL1738 certified
Condensate drain requirements
An external condensate drain (not supplied with the
heater) must be installed under the following
conditions:
• All vertical terminating vent installations.
• Horizontal terminating vent installations where the
total linear vent length is greater than 6 feet (1.8 m).
• Vent installations where any section of the exhaust
vent pipe passes through an unconditioned space.
Minimum combustion air and exhaust pipe
length
The minimum exhaust pipe length is 1 foot (0.3m) of
straight vent pipe. The minimum combustion air pipe
length is one 90° elbow.
Description Length
Kit part no.
and quantity
196016
3- In. Rain Cap N/A 1
4- In. Diameter SDR-26
Pipe 24 In. long 1
3- In. Y
Concentric Fitting N/A 1
2- ½ In. Diameter SDR-
26 Pipe
37-1/8 in.
long 1
3- In. Condensate drain
Tee N/A 1
1.5- In. Condensate drain
bushing N/A 1
Table 3 Concentric vent part breakdown
6720608836-27.2V
3 (76mm)"
3 (76mm)"
INTAKE
EXHAUST
COMBUSTION
AIR
MAINTAIN 12 IN. (18 IN. FOR CANADA)
MINIMUM CLEARANCE ABOVE
HIGHEST ANTICIPATED SNOW LEVEL.
MAXIMUM OF 24 IN. ABOVE ROOF.
EXHAUST
ROOF BOOT/
FLASHING (FIELD
SUPPLIED
DRAIN TEE
(196278)
CONCENTRIC
VENT KIT
(196016)
Diam. Aproved terminals
E
x
h
a
u
s
t
3 or 4 inches
“T” terminal
90° elbow
PVC Flue Cap*
(ECAP321)
Vertical terminations only
3" diameter only
Concentric
(196016)
I
n
t
a
k
e
3 or 4 inches
“T” terminal
90° elbow
PVC Flue Cap*
(ECAP321)
Vertical & horizontal terminations approved
3" diameter only
Concentric
(196016)
Table 4 Venting specifications for intake and exhaust

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12
Installation instructions
Maximum combustion air and exhaust pipe
length
The following tables display the maximum allowable
straight pipe lengths for combustion air and exhaust
piping with consideration to the number of elbows
used. Reduce the equivalent length for each elbow
used from the maximum allowable length depending on
the system used. Refer to table 5 if using 3" diameter
venting. Refer to table 6 if using 4" diameter venting.
Use of elbows
It is recommended to limit the amount of elbows used in
the exhaust and combustion air piping to reduce friction
in the air flow. The following lists the maximum amount
of 90° elbows allowed in either the exhaust or combus-
tion air piping:
3"
Venting Maximum
allowable
Exhaust
pipe length
Maximum
allowable
Combustion
air pipe
length
Elbow
Equivalency
90° 45°
Twin pipe
system
31ft 31ft 5 ft 3 ft
Concen-
tric system
23ft 23ft 5 ft 3 ft
Table 5 Maximum Allowable Exhaust and Combustion
Air Lengths for 3" venting
4"
Venting Maximum
allowable
Exhaust
pipe length
Maximum
allowable
Combustion
air pipe
length
Elbow
Equivalency
90° 45°
Twin pipe
system
63ft 63ft
2.5ft 1.5ft
Concen-
tric system
43ft 43ft
2.5ft 1.5ft
Table 6 Maximum Allowable Exhaust and Combustion
Air Lengths for 4" venting
Max. number of 90°
elbows
3"
venting
4"
venting
Twin pipe system 5 7
Concentric system 4 7
Table 7
i
Two 45° elbows are equal to one 90°
elbow. Any combination of 45° and
90° elbows may be used in the vent
system as long as the combination
does not exceed the maximum listed
in table 7 above.

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Installation instructions
13
Calculation example for 3" venting:
Exhaust
Combustion air
Calculation example for 4" venting:
Exhaust
Combustion air
System used Concentric
Number of 90° elbows needed: 1
Number of 45° elbows needed: 2
Table 8
Calculation of example
Max. length 23’
90° elbow reduction - 5’
sub-total = 18’
45° elbow reduction - 6’
Total = 12’
Table 9
i
For this example, the maximum allowable
exhaust pipe length is 12 feet.
System used Concentric
Number of 90° elbows needed: 2
Number of 45° elbows needed: 1
Table 10
Calculation of example
Max. length 23’
90° elbow reduction - 10’
sub-total = 13’
45° elbow reduction - 3’
Total = 10’
Table 11
i
For this example, the maximum allowable
combustion air pipe length is 10 feet.
System used Twin pipe
Number of 90° elbows needed: 1
Number of 45° elbows needed: 2
Table 12
Calculation of example
Max. length 63’
90° elbow reduction - 2.5’
sub-total = 61.5’
45° elbow reduction - 3’
Total = 58.5’
Table 13
i
For this example, the maximum allowable
exhaust pipe length is 58.5 feet.
System used Twin pipe
Number of 90° elbows needed: 2
Number of 45° elbows needed: 2
Table 14
Calculation of example
Max. length 63’
90° elbow reduction - 5’
sub-total = 58’
45° elbow reduction - 3’
Total = 55’
Table 15
i
For this example, the maximum allowable
combustion air pipe length is 55 feet.

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14
Installation instructions
Required direct vent terminal clearances (twin pipe / concentric penetration)
Fig. 9
*For clearances not specified in ANSI Z223.1 / NFPA 54 or CSA-B149.1, one of the following shall be indicated:
a) A minimum clearance value determined by testing in accordance with section 2.20, or;
b) A reference to the following footnote:
“Clearance in accordance with local installation codes and the requirements of the gas supplier.”
6720608836-23.1Av
Canadian installations
1)
U.S. installations
2)
AClearance above grade, veranda, porch, deck or balcony 12 in. 12 in.
BClearance to window or door that may be opened 36 in. 12 in.
CClearance to permanently closed window * *
DVertical clearance to ventilated soffit located above the vent
terminator within a horizontal distance of 2 feet (61cm) from the
center line of the terminator
* *
EClearance to unventilated soffit * *
FClearance to outside corner * *
GClearance to inside corner * *
HClearance to each side of center line extended above meter/
regulator assembly
36 in. within a height 15 feet above
meter/ regulator assembly
*
IClearance to service regulator vent outlet 36 in. *
JClearance to non-mechanical air supply inlet to building or the
combustion air inlet to any other application
36 in. 12 in.
KClearance to mechanical air supply inlet 72 in. 36 in. above if within 10 feet
horizontally
LClearance above paved sidewalk or paved driveway located on
public property
84 in.
3)
*
MClearance under veranda, porch deck or balcony 12 in.
4)
*
Table 16
1) In accordance with the current CSA B149.1 Natural Gas and Propane Installation Code
2) In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Gas Code
3) A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.
4) Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor.

6 720 646 812
Installation instructions
15
Required other than direct vent terminal clearances (single pipe penetration)
Fig. 10
*For clearances not specified in ANSI Z223.1 / NFPA 54 or CSA-B149.1, one of the following shall be indicated:
a) A minimum clearance value determined by testing in accordance with section 2.20, or;
b) A reference to the following footnote:
“Clearance in accordance with local installation codes and the requirements of the gas supplier.”
6720608836-23.1Av
Canadian installations
1)
U.S. installations
2)
AClearance above grade, veranda, porch, deck or balcony 12 in. 12 in.
BClearance to window or door that may be opened 36 in. 4 feet below or to side of opening;
1 foot above opening
CClearance to permanently closed window * *
DVertical clearance to ventilated soffit located above the vent
terminator within a horizontal distance of 2 feet (61cm) from the
center line of the terminator
* *
EClearance to unventilated soffit * *
FClearance to outside corner * *
GClearance to inside corner * *
HClearance to each side of center line extended above meter/
regulator assembly
36 in. within a height 15 feet above
meter/ regulator assembly
*
IClearance to service regulator vent outlet 36 in. *
JClearance to non-mechanical air supply inlet to building or the
combustion air inlet to any other application
36 in. 4 feet below or to side of opening;
1 foot above opening
KClearance to mechanical air supply inlet 72 in. 36 in. above if within 10 feet
horizontally
LClearance above paved sidewalk or paved driveway located on
public property
84 in.
3)
84 in.
MClearance under veranda, porch deck or balcony 12 in.
4)
*
Table 17
1) In accordance with the current CSA B149.1 Natural Gas and Propane Installation Code
2) In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Gas Code
3) A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.
4) Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor.

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16
Installation instructions
3.3.3 Vent configuration examples
Below are approved examples of vertical and horizontal
venting installations.
Fig. 11 Vertical venting system (single pipe penetra-
tion)
Fig. 12 Horizontal venting installation (combustion air
piping not shown)
Warning: Single pipe penetration should be used in
non-freezing climates only!
Fig. 13 Horizontal venting system (concentric vent)
Fig. 14 Horizontal parallel venting system (twin pipe
direct vent)
6720608836-24.2V
3" (80mm)
INTAKE
EXHAUST
MAINTAIN 12 IN. (18 IN. FOR CANADA)
MINIMUM CLEARANCE ABOVE
HIGHEST ANTICIPATED SNOW LEVEL.
MAXIMUM OF 24 IN. ABOVE ROOF.
DRAIN TEE
4"
HORIZONTAL RUN
DOWN TO
TERMINATOR.
SIDE
OF
WATER
HEATER
NOTE:
MINIMUM 1FT OF
STRAIGHT VENT PIPE
REQUIRED
6720608542-10.1V
6720608643-11.2V
3" (80mm)
3" (80mm)
INTAKE
EXHAUST
MINIMUM
1”
EXHAUST
COMBUSTION
AIR
DRAIN TEE
6720608836-25.1Av

6 720 646 812
Installation instructions
17
Fig. 15 Horizontal venting system (single pipe pene-
tration)
*Warning: Single pipe penetration should be
used in non-freezing climates only!
3.3.4 Vent connections
Attaching the exhaust and air inlet connection
adaptors to the top of the heater
BAttach the flue gas exhaust accessory to the top of
the unit Fig. 16 (position 1) using the 4 screws and
gasket provided, and fully insert vent pipe into the
accessory. If using 4" venting, a 3" to 4" increaser
should be installed directly after this accessory.
Fig. 16 Exhaust connection
BAttach the combustion air inlet accessory to the top
of the unit Fig. 17 (position 2) using the 3 screws and
gasket provided, and install 3" air intake pipe over the
accessory.
Fig. 17 Inlet connection
3.3.5 Connecting the condensate water drain
i
NOTE: Vent pipe must be completely
vertical when inserting or blue gasket
inside exhaust accessory can become
displaced. Exhaust accessory can be
removed with vent pipe attached to check
gasket position.
6720608643-12.2V
3" (80mm)
INTAKE
EXHAUST
4” Min.
DRAIN TEE
i
NOTE: The combustion air accessory can
be installed on the top right or on the top
left side of the heater. The combustion air
inlet that is not used must be kept sealed.
Warning:
BFailure to properly install condensate
drain can damage the appliance and will
void the warranty.
Warning:
BDo not install condensate drain tubing in
areas where it may freeze.

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Installation instructions
Appliance condensate drain installation
The appliance comes equipped with an internal
condensate drain and siphon. This drains condensation
formed in the secondary heat exchanger. Piping must
be installed under the condensate drain outlet on the
water heater and piped for disposal in accordance with
local codes.
Fig. 18 Appliance drain installation
External condensate drain installation
If an external condensate drain (installer supplied) must
be installed (Section 3.3.2), the following is
recommended:
• 1. Install condensate drain on a horizontal section of
the exhaust pipe as close to the heater as possible.
• 2. The condensate must be disposed of according to
local codes.
• 3. To install condensate drain in vent system, use
PVC 3" X 3" X 1.5" tee (part# 196278) and reduce
for drain connection.
Fig. 19 External condensate drain installation
3.3.6 Freeze prevention
In cold climates, components of a tankless water heater
can freeze and burst from negative draft. A leading
cause of negative draft is combustion appliances in the
building not being supplied with sufficient combustion
air. A wood stove or furnace can pull its combustion air
from the water heater‘s vent pipe, allowing the cold
incoming air to freeze the cold water in the heat
exchanger. Supplying more combustion air for all com-
bustion appliances is the solution. A HVAC specialist
should be consulted to design solutions for providing
more combustion air.
Listed below is an additional measure designed to fur-
ther limit backdraft in extreme conditions assuming all
other possible causes have been addressed.
i
The condensate must be disposed of in
accordance with local codes.
See chapter 3.11 “Filling the condensate
trap”.
i
Use materials approved by the authority
having jurisdiction. In the absence of other
authority, PVC, and CPVC pipe must
comply with ASTM D1785, F441 or
D2665. Cement and primer must comply
with ASTM D2564 or F493. For Canada,
use CSA or ULC certified PVC or CPVC
pipe, fittings and cement, see table 2.
Leave min. ¼" air gap
1 ½" x ½" PVC Reducer
Trap required
6720608643-17.2V
Dispose of condensate in
accordance with local codes
4” Min.
Condensate drain

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Installation instructions
19
Backdraft reducer
The Heat Fab backdraft reducer (9301BFP) is the pre-
ferred option for limiting backdraft (see Fig. 20).
Note: The following solution is available only for
3" diameter venting.
Fig. 20 Part nr 9301BFP
Installation
For this solution to be effective, the internal flapper must
be 100% closed when the water heater is not running.
Refer to Figures 22 and 23 for preferred installation
positions in the vent system.
Installation considerations:
• Install damper per the supplied manufacturer‘s
instructions.
• The damper is only to be used in the exhaust vent
piping.
• Ensure directional arrow on damper label faces in the
same direction as exhaust flow.
• If installed horizontally, the axis must be horizontal or
slightly pitched up towards termination to ensure
damper closes 100% when heater is not running.
• To allow accessibility, damper must not be installed
in an enclosed section of vent pipe.
• Do not install damper in unconditioned spaces (e.g.
attics) Condensation can build up while the heater is
running which can later freeze and potentially block
the flapper.
Fig. 21 Blackflow reducer (9301BFP) installed
Fig. 22
Fig. 23
6720608643-18.1V
6720608643-19.1V
6720608542-06.2V
Preferred damper position for vertical terminations
Unconditioned
space. Do not
install damper.
Enclosed vent
pipe. Do not
install damper.
6720608836-30.2V

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20
Installation instructions
3.3.7 Fan speed adjustment
! IMPORTANT INFORMATION:
Natural gas heaters with installation altitudes
below 2,000 ft above sea level disregard this
section.
Installation adjustment:
After installing the tankless water heater, the fan speed
values for minimum power (P2) and maximum power
(P1) may need adjustment due to variations in altitude
and vent pipe length. Failure to make necessary
adjustments to fan speed values may result in improper
operation of the appliance.
First calculate the total equivalent vent length. This is
the straight pipe length of both exhaust and combustion
air plus the number of elbows used. To determine the
length equivalency of each elbow refer to tables 5 and
6.
Use the equivalent vent length value to determine the
appropriate fan speed values found in table 18 and 19.
Refer to page 22 on how to adjust the fan speeds if an
adjustment is necessary. After changing fan speed val-
ues, proceed to section 6.5 to confirm CO2 values are
within specified ranges.