Shield SNR126-065 Supplement

Installation & Service
Manual
Models: SNR126-065, SNR151-100,
SNR201-100, SNA151-100, SNA201-100,
SNA286-125, SNA401-125, AND SNA501-125
This manual must only be used by
a qualified heating installer / service
technician. Read all instructions in
this manual before installing. Perform
steps in the order given. Failure to
comply could result in severe personal
injury, death, or substantial property
damage.
WARNING
Save this manual for future reference.
-- 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
• 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 near by 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.
WARNING: If the information in these instructions
is not followed exactly, a fire or explosion may result
causing property damage, personal injury or death.
SHW-I-S Rev B

2
Contents
PLEASE READ BEFORE PROCEEDING ...................... 3
Hazard Definitions ...................................................... 3
THE SHIELD -- HOW IT WORKS ............................... 4-6
RATINGS......................................................................... 7
1. DETERMINE WATER HEATER LOCATION
Closet and Alcove Installations........................................ 8
Provide Clearances.......................................................... 8
Flooring and Foundation................................................ 10
Remove Water Heater from Wood Pallet ...................... 10
Prevent Combustion Air Contamination......................... 10
Using an Existing Vent System to Install a New Water
Heater............................................................................. 11
Removing Water Heater From Existing Common Vent. 11
Combustion & Ventilation Air Requirements............ 12-14
2. GENERAL VENTING
Direct Venting Options................................................... 15
Install Vent and Combustion Air Piping ......................... 16
Requirements for Installation in Canada........................ 17
Sizing ............................................................................. 17
Min./Max. Combustion Air & Vent Piping Lengths..........17
Materials..........................................................................18
Optional Room Air.......................................................... 19
PVC/CPVC..................................................................... 20
Polypropylene................................................................. 21
Stainless Steel Vent....................................................... 22
3. SIDEWALL DIRECT VENTING.................... 23-29
4. VERTICAL DIRECT VENTING............................ 30-33
5. SYSTEM PIPING
General Piping ............................................................... 34
Scalding.................................................................... 34
Water Chemistry....................................................... 35
Piping Components........................................................ 35
Piping Diagrams .................................................. 36-38
6. GAS CONNECTIONS
Connecting Gas Supply Piping...................................... 39
Natural Gas.................................................................... 40
Pipe Sizing for Natural Gas...................................... 40
Natural Gas Supply Pressure Requirements ........... 40
Propane Gas.................................................................. 40
Pipe Sizing for Propane Gas.................................... 40
Propane Supply Pressure Requirements................. 40
Check Inlet Gas Supply ............................................ 41-42
Gas Pressure ................................................................. 42
Gas Valve Replacement ................................................ 42
7. FIELD WIRING
Low Voltage Connections .............................................. 43
Enable Switch ................................................................ 43
Louver Relay Output / Louver Proving Switch Input...... 43
Power Cord Connection ................................................ 43
Runtime Contacts .......................................................... 43
Alarm Contacts .............................................................. 43
8. CONDENSATE DISPOSAL
Condensate Drain............................................................ 46
9. START-UP
Check for Gas Leaks ....................................................... 47
Inspect/fill Condensate System........................................ 47
Final Checks Before Starting the Water Heater.......... 47-50
10. OPERATING INFORMATION
How the Water Heater Operates...................................... 51
Temperature Control........................................................ 51
Protection Features.......................................................... 51
Water Heater Temperature Regulation............................ 52
Adjustable Control Parameters................................... 52-53
The Shield Control Module .............................................. 54
11. MAINTENANCE
Maintenance and Annual Startup..................................... 55
Address Reported Problems ...................................... 56
Inspect Water Heater Interior ..................................... 56
Clean Condensate Trap ............................................. 56
Check All Piping for Leaks.......................................... 56
Flue Vent System and Air Piping................................ 56
Check Water System.................................................. 56
Check Expansion Tank............................................... 57
Check Water Heater Relief Valve............................... 57
Inspect Ignition & Flame Sense Electrodes................ 57
Check Ignition Ground Wiring..................................... 57
Check All Water Heating Wiring................................. 57
Check Control Settings............................................... 57
Perform Startup & Checks.......................................... 57
Check Burner Flames................................................. 58
Check Flame Signal ................................................... 58
Review with Owner..................................................... 58
Handling Ceramic Fiber Materials.............................. 58
Cleaning Heat Exchanger...................................... 58-59
Oiled Bearing Circulators............................................ 59
Magnesium Anode Rod Inspection............................. 59
Check Delta T............................................................. 59
12. TROUBLESHOOTING
Before Troubleshooting.................................................... 60
Troubleshooting Chart - No Display........................... 61
Checking Temperature Sensors................................. 62
Troubleshooting Chart - Noisy System....................... 63
Troubleshooting Chart - Fault Messages
Displayed............................................................... 64-69
Combustion Analysis Procedure...................................... 70
Gas Valve Adjustment Procedure.................................... 71
13. DIAGRAMS
Ladder Diagram ............................................................... 72
Wiring Diagram................................................................. 73

Please read before proceeding
Installer – Read all instructions, in this
manual before installing. Perform steps in
the order given.
Have this water heater serviced/inspected by a
qualified service technician, at least annually.
Failure to comply with the above could result
in severe personal injury, death or substantial
property damage.
Failure to adhere to the guidelines on this
page can result in severe personal injury,
death, or substantial property damage.
Water heater operation –
• Do not block flow of combustion or ventilation air to
the water heater.
• Should overheating occur or gas supply fail to shut off,
do not turn off or disconnect electrical supply to
circulator. Instead, shut off the gas supply at a location
external to the appliance.
• Do not use this water heater if any part has been under
water. The possible damage to a flooded appliance can
be extensive and present numerous safety hazards. Any
appliance that has been under water must be replaced.
When calling or writing about the water
heater – Please have the water heater model
and serial number from the water heater
rating plate.
Consider piping and installation when
determining water heater location.
Any claims for damage or shortage in
shipment must be filed immediately against
the transportation company by the consignee.
Factory warranty (shipped with unit) does
not apply to units improperly installed or
improperly operated.
3
If the information in these instructions 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.
-- 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 near by 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.
WARNING
NOTICE
WARNING
WARNING
Hazard definitions
The following defined terms are used throughout this manual to bring attention to the presence of hazards of various risk levels
or to important information concerning the life of the product.
DANGER
WARNING
CAUTION
CAUTION
NOTICE
DANGER indicates an imminently hazardous situation which, if not avoided, will result in death or serious
injury.
WARNING indicates a potentially hazardous situation which, if not avoided, could result in death or serious
injury.
CAUTION indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate
injury.
CAUTION used without the safety alert symbol indicates a potentially hazardous situation which, if not
avoided, may result in property damage.
NOTICE indicates special instructions on installation, operation, or maintenance that are important but not
related to personal injury or property damage.
When servicing the water heater –
• To avoid electric shock, disconnect electrical supply
before performing maintenance.
• To avoid severe burns, allow the water heater to cool
before performing maintenance.
Installation & Service Manual

4
The Shield - How it works...
1. Access cover - front
Provides access to the gas train, heat exchanger and controls.
2. Air intake adapter
Allows for the connection of the PVC air intake pipe to the
water heater.
3. Air pressure switch
The air pressure switch detects blocked inlet conditions.
4. Air shroud (501-125 Model Only_Not Shown)
The air shroud directs air and gas flow into the blower.
5. Blower
The blower pulls in air and gas through the venturi
(item 32). Air and gas mix inside the blower and are pushed into
the burner, where they burn inside the combustion chamber.
6. Burner (not shown)
Made with metal fiber and stainless steel construction, the
burner uses pre-mixed air and gas and provides a 5 to 1 firing
rate.
7. Condensate drain connection
Connects the condensate drain line to 1/2" PVC.
8. Electronic Control Module
The electronic control responds to internal and external signals
and controls the blower, gas valve, and pump to meet the
demand.
9. Electronic display
The electronic display consists of 4 buttons, and a liquid crystal
display. The display is used to make adjustments and read
water heater status.
10. Flame inspection window (not shown)
The quartz glass window provides a view of the burner
surface and flame.
11. Flame sensor
Used by the control module to detect the presence of burner
flame.
12. Flue gas sensor (not shown)
This sensor monitors the flue gas exit temperature. The control
module will modulate and shut down the water heater if the
flue gas temperature gets too hot. This protects the flue pipe
from overheating.
13. Gas connection pipe
Threaded pipe connection, either 1/2", 3/4", or 1",
depending on the model. This pipe should be connected
to the incoming gas supply for the purpose of delivering
gas to the water heater.
14. Gas shutoff switch (151-100 - - 286-125 Models Only)
An electrical switch designed to cut power from the gas valve to
prevent gas flow to the burner.
15. Gas shutoff valve (401-125 -- 501-125 Models Only)
Manual valve used to isolate the gas valve from the gas supply.
16. Gas valve
The gas valve senses the negative pressure created by the
blower, allowing gas to flow only if the gas valve is powered and
combustion air is flowing.
17. Heat exchanger access cover
Allows access to the combustion side of the heat exchanger
coils.
18. Heat exchanger inlet temperature sensor
This sensor monitors the inlet water temperature to the heat
exchanger.
19. Heat exchanger outlet temperature sensor
This sensor monitors heat exchanger outlet water temperature.
20. Ignition electrode
Provides direct spark for igniting the burner.
21. Line voltage junction box
The junction box contains the connection points for the line
voltage power.
22. Low voltage connection board
The connection board is used to connect external low voltage
devices.
23. Low voltage wiring connections (knockouts)
Conduit entryway for the low voltage connection board.
24. Power cord
The power cord allows for quick connection to 120V supply.
25. Pump
Circulates water between the tank and the heat exchanger.
26. Pump relay
Switches power to the pump.
27. Relief valve
Protects the heat exchanger from over pressure and
temperature conditions. The relief valve is set at 150 PSI.
28. Stainless steel heat exchanger
Allows water to flow through specially designed coils for
maximum heat transfer, while providing protection against
flue gas corrosion. The coils are encased in a jacket that
contains the combustion process.
29. Tank sensor
Used by the control to monitor the temperature of the tank.
30. Pump access panel
Panel used to gain access to the pump and condensate trap;
also used to gain access to the outlet water sensor on Models
286-125 -- 501-125 only.
31. Vent pipe connection
Allows for the connection of the vent pipe system to the water
heater.
32. Venturi
The venturi controls air and gas flow into the burner.
33. Water heater drain valve
Location from which the water heater can be drained.
34. Water inlet
Copper sweat connection for cold water supply that returns
water from the system to the heat exchanger, either 1-1/2" or 2",
depending on the model.
35. Water outlet
Copper sweat connection that supplies hot water to the
system, either 1-1/2" or 2", depending on the model.
36. Over-temp switch (286-125 --501-125 Models Only)
An electrical switch designed to shut down water heater
operation in the event the outer back of the heat exchanger,
directly above the flue connection exceeds 604°F (318°C).
This is a one time switch and could warrant a heat exchanger
replacement. Check the integrity of the rear refractory at the
back of the upper coil if the switch opens.
Installation & Service Manual

1
24
9
34
29
IMG00461
Front View - Models 126-065 -- 201-100
28
21 2
16
32
13
5
35
24
9
3
14
20
11
8
22
IMG00461
Left Side (inside unit) -- Models 126-065 -- 201-100
18
19
25
3
26
7
33
9
21
17
IMG00461
Right Side (inside unit) -- Models 126-065 -- 201-100
The Shield - How it works... (continued)
34
2
23
31
27
35
7
13
30
IMG00461
Rear View - Models 126-065 -- 201-100
5
Models 126-065 -- 201-100
Installation & Service Manual

6
The Shield - How it works...
31
34
18
25
15
19
28
36
27
7
2
35
IMG00461
Rear View - Models 286-125 -- 401-125
31
34
18
25
15
19
28
36
27
7
2
35
IMG00461
Rear View - Model 501-125 Right Side (inside unit) - Model 501-125
Right Side (inside unit) - Models 286-125 -- 401-125
Models 286-125 -- 401-125
Model 501-125
5
22
26
33
29
32
24
23
1
21
17
9
16
3
13
35
14
20
11
8
IMG00461
IMG00461
5
22
26
33
29
32
24
23
1
21
17
9
16
3
13
35
14
20
11
8
Installation & Service Manual

Ratings
Notes:
1. Shield water heaters require special gas venting. Use
only the vent materials and methods specified in the
Shield Installation and Service Manual.
2. Standard Shield water heaters are equipped to operate
from sea level to 4,500 feet only with no adjustments.
The water heater will de-rate by 4% for each 1,000 feet
above sea level up to 4,500 feet.
3. High altitude Shield water heaters are equipped to
operate from 3,000 to 12,000 feet only with no field
adjustments. The water heater will de-rate by 2% for
each 1,000 feet above 3,000 feet. High altitude models
are manufactured with a different control module
for altitude operation, but the operation given in this
manual remains the same as the standard models. A
high altitude label (as shown in FIG. A) is also affixed
to the unit.
7
Maximum allowed working pressure is located on the rating plate.
Model Number
Note: Change “N”
to “L” for L.P. gas
models.
CSA
Input Modulation Btu/hr
(Note 2)
Water Content
Gallons Water Connections Gas Connections Vent/Air Size
Min Max (Note 1)
SNR126-065 25,000 - 125,000 TBD 1-1/2" 1/2" 3"
SNR151-100 30,000 - 150,000 TBD 1-1/2" 1/2" 3"
SNA151-100 30,000 - 150,000 TBD 1-1/2" 1/2" 3"
SNR201-100 40,000 - 200,000 TBD 1-1/2" 1/2" 3"
SNA201-100 40,000 - 200,000 TBD 1-1/2" 1/2" 3"
SNA286-125 57,000 - 285,000 TBD 2" 3/4" 4"
SNA401-125 80,000 - 400,000 TBD 2" 1" 4"
SNA501-125 100,000 - 500,000 TBD 2" 1" 4"
NOTICE
Figure A High Altitude Label Location
UNIT EQUIPPED FOR
HIGH ALTITUDE
3,000 FT. TO 12,000 FT.
IMG00462
Installation & Service Manual
HLW LOW LEAD CONTENT

8
The Shield water heater gas manifold
and controls met safe lighting and other
performance under tests specified in
ANSI Z21.10.3 – latest edition.
Failure to keep water heater area clear and
free of combustible materials, gasoline,
and other flammable liquids and vapors
can result in severe personal injury, death,
or substantial property damage.
Installation must comply with:
• Local, state, provincial, and national codes, laws,
regulations, and ordinances.
• National Fuel Gas Code, ANSI Z223.1 – latest edition.
• National Electrical Code.
• For Canada only: B149.1 Installation Code, CSA C22.1
Canadian Electrical Code Part 1 and any local codes.
Before locating the water heater, check:
1. Check for nearby connection to:
• Water piping
• Venting connections
• Gas supply piping
• Electrical power
2. Locate the appliance so that if water connections should
leak, water damage will not occur. When such locations
cannot be avoided, it is recommended that a suitable
drain pan, adequately drained, be installed under the
appliance. Under no circumstances is the manufacturer
to be held responsible for water damage in connection
with this appliance, or any of its components.
3. Check area around the water heater. Remove any
combustible materials, gasoline and other flammable
liquids.
4. The Shield water heater must be installed so that gas
control system components are protected from dripping
or spraying water or rain during operation or service.
WARNING
Provide clearances:
Clearances from combustible materials
1. Hot water pipes—at least 1/4" from combustible
materials.
2. Vent pipe – at least 1" from combustible materials.
3. See FIG.’s 1-1 and 1-2 on page 9 for other clearance
minimums.
Clearances for service access
1. See FIG.’s 1-1 and 1-2 on page 9 for recommended
service clearances. If you do not provide the minimum
clearances shown, it may not be possible to service the
water heater without removing it from the space.
Closet and alcove installations
This appliance requires a special venting
system. The vent connection to the
appliance must be made with the CPVC
pipe section provided with the appliance.
The field provided vent fittings must
be cemented to the CPVC pipe section.
Use only the vent materials, primer and
cement specified in this manual to make
the vent connections. Failure to follow
this warning could result in fire, personal
injury, or death.
For closet and alcove installations as
shown in FIG.’s 1-1 and 1-2, CPVC or
stainless steel vent material must be used
inside the structure. The ventilating air
openings shown in FIG.’s 1-1 and 1-2 are
required for this arrangement. Failure to
follow this warning could result in fire,
personal injury, or death.
WARNING
WARNING
NOTICE
WARNING
1 Determine water heater location
Installation & Service Manual
A closet is any room the water heater is installed in which is
less than 433 cubic feet for 126-065 and 201-100 models and
638 cubic feet for the 286-125 through 501-125 models.
An alcove is any room which meets the criteria for a closet
with the exception that it does not have a door.
Example: Room dimensions = 6 feet long, 6 feet wide, and
9 foot ceiling = 6 x 6 x 9 = 324 cubic feet. This would be
considered a closet for a Shield Water Heater.
This appliance is certified as an indoor
appliance. Do not install the appliance
outdoors or locate where the appliance will
be exposed to freezing temperatures or to
temperatures that exceed 100°F.
Do not install the appliance where the
relative humidity may exceed 93%. Do not
install the appliance where condensation
may form on the inside or outside of the
appliance, or where condensation may fall
onto the appliance.
Failure to install the appliance indoors
could result in severe personal injury,
death, or substantial property damage.

OPEN FRONT
1/4" (6.35 MM)
MINIMUM CLEARANCE
AROUND HOT WATER PIPES
1" (25.4 MM)
MINIMUM CLEARANCE
AROUND VENT PIPE
IMG00463
Figure 1-2 Alcove Installation - Minimum Required Clearances
6"
6"
CLOSED DOOR
VENTILATIING
AIR OPENING
VENTILATIING
AIR OPENING
1/4" (6.35 MM)
MINIMUM CLEARANCE
AROUND HOT WATER PIPES
1" (25.4 MM)
MINIMUM CLEARANCE
AROUND VENT PIPE
IMG00463
Figure 1-1 Closet Installation - Minimum Required Clearances
WARNING
9
1 Determine water heater location (continued)
RECOMMENDED SERVICE
CLEARANCES:
Top - 18" (457 mm)
Left/Right Side - 24" (610 mm)
Front - 24" (610 mm)
RECOMMENDED SERVICE
CLEARANCES:
Top - 18" (457 mm)
Left/Right Side - 24" (610 mm)
Front - 24" (610 mm)
Installation & Service Manual
WARNING
For closet installations, CPVC,
polypropylene or stainless steel
vent material MUST BE used in
a closet structure due to elevated
temperatures. Failure to follow
this warning could result in fire,
personal injury, or death.
For alcove installations, CPVC,
polypropylene or stainless steel
vent material MUST BE used
in an alcove structure due to
elevated temperatures. Failure to
follow this warning could result
in fire, personal injury, or death.

10
Do not install the water heater on carpeting
even if foundation is used. Fire can result,
causing severe personal injury, death, or
substantial property damage.
When local codes require compliance with NSF 5, the heater
must be sealed to the floor with a food grade silicone to prevent
debris and harborage of vermin under the heater.
If flooding is possible, elevate the water heater sufficiently to
prevent water from reaching the water heater.
Flooring and foundation
Flooring
The Shield water heater is approved for installation on
combustible flooring, but must never be installed on carpeting.
Prevent combustion air contamination
Install air inlet piping for the Shield water heater as described
in this manual. Do not terminate vent/air in locations that can
allow contamination of combustion air. Refer to Table 1A, for
products and areas which may cause contaminated combustion
air.
Ensure that the combustion air will not
contain any of the contaminants in Table 1A.
Contaminated combustion air will damage
the water heater, resulting in possible severe
personal injury, death or substantial property
damage. Do not pipe combustion air near a
swimming pool, for example. Also, avoid
areas subject to exhaust fumes from laundry
facilities. These areas will always contain
contaminants.
WARNING
WARNING
1 Determine water heater location
Remove water heater from wood pallet
1. Remove the sides and the top of the crate.
2. Remove the blocks on the base of the crate to allow for
easier removal.
3. The water heater can then be slid off the base of the crate for
installation.
Do not drop the water heater or bump the
jacket on the floor or pallet. Damage to the
water heater can result.
NOTICE
Installation & Service Manual
Products to avoid:
Spray cans containing chloro/fluorocarbons
Permanent wave solutions
Chlorinated waxes/cleaners
Chlorine-based swimming pool chemicals
Calcium chloride used for thawing
Sodium chloride used for water softening
Refrigerant leaks
Paint or varnish removers
Hydrochloric acid/muriatic acid
Cements and glues
Antistatic fabric softeners used in clothes dryers
Chlorine-type bleaches, detergents, and cleaning solvents
found in household laundry rooms
Adhesives used to fasten building products and other similar
products
Areas likely to have contaminants
Dry cleaning/laundry areas and establishments
Swimming pools
Metal fabrication plants
Beauty shops
Refrigeration repair shops
Photo processing plants
Auto body shops
Plastic manufacturing plants
Furniture refinishing areas and establishments
New building construction
Remodeling areas
Garages with workshops
Table 1A Corrosive Contaminants and Sources

When removing a water heater from
existing common vent system:
Do not install the Shield water heater
into a common vent with any other
appliance. This will cause flue gas spillage
or appliance malfunction, resulting in
possible severe personal injury, death, or
substantial property damage.
Failure to follow all instructions can result
in flue gas spillage and carbon monoxide
emissions, causing severe personal injury
or death.
At the time of removal of an existing water heater, the
following steps shall be followed with each appliance
remaining connected to the common venting system placed
in operation, while the other appliances remaining connected
to the common venting system are not in operation.
a. Seal any unused openings in the common venting system.
b. Visually inspect the venting system for proper size and
horizontal pitch and determine there is no blockage
or restriction, leakage, corrosion, or other deficiencies,
which could cause an unsafe condition.
c. Test vent system – Insofar as is practical, close all building
doors and windows and all doors between the space
in which the appliances remaining connected to the
common venting system are located and other spaces of
the building. Turn on clothes dryers and any appliance
not connected to the common venting system. Turn on
any exhaust fans, such as range hoods and bathroom
exhausts, so they will operate at maximum speed. Do not
operate a summer exhaust fan. Close fireplace dampers.
d. Place in operation the appliance being inspected. Follow
the lighting instructions. Adjust thermostat so appliance
will operate continuously.
e. Test for spillage at the draft hood relief opening after
5 minutes of main burner operation. Use the flame of a
match or candle, or smoke from a cigarette, cigar, or pipe.
f. After it has been determined that each appliance
remaining connected to the common venting system
properly vents when tested as outlined herein, return
doors, windows, exhaust fans, fireplace dampers, and any
other gas-burning appliance to their previous conditions
of use.
g. Any improper operation of the common venting system
should be corrected so the installation conforms with the
National Fuel Gas Code, ANSI Z223.1/NFPA 54 and/or
CAN/CSA B149.1, Natural Gas and Propane Installation
Code. When resizing any portion of the common venting
system, the common venting system should be resized
to approach the minimum size as determined using the
appropriate tables in Part 11 of the National Fuel Gas
Code, ANSI Z223.1/NFPA and/or CAN/CSA B149.1,
Natural Gas and Propane Installation Code.
DANGER
WARNING
1 Determine water heater location (continued)
11
Installation & Service Manual
Failure to follow all instructions can result
in flue gas spillage and carbon monoxide
emissions, causing severe personal injury
or death.
WARNING
When using an existing vent system to
install a new water heater:
Check the following venting components before installing:
• Material - For materials listed for use with this appliance,
see Section 2 - General Venting. For polypropylene or
stainless steel venting, an adapter of the same
manufacturer must be used at the flue collar connection.
• Size - To ensure proper pipe size is in place, see Table 2A.
Check to see that this size is used throughout the vent
system.
• Manufacturer - For a stainless steel or polypropylene
application, you must use only the listed manufacturers
and their type product listed in Tables 2E and 2G for CAT
IV positive pressure venting with flue producing
condensate.
• Supports - Non-combustible supports must be in place
allowing a minimum 1/4" rise per foot. The supports
should adequately prevent sagging and vertical slippage,
by distributing the vent system weight. For additional
information, consult the vent manufacturer’s
instructions for installation.
• Terminations - Carefully review Sections 2 through 4 to
ensure requirements for the location of the vent and air
terminations are met and orientation of these fit the
appropriate image from the Sidewall or Vertical
options listed in the General Venting Section. For
stainless steel vent, only use terminations listed in Table
2H for the manufacturer of the installed vent.
• Seal - With prior requirements met, the system should be
tested to the procedure listed in parts (c) through (f) of
the Removal of an Existing Water Heater Section, this
page.
With polypropylene and stainless steel vent, seal and connect
all pipe and components as specified by the vent manufacturer
used; with PVC/CPVC vent, see the Installing Vent or Air
Piping Section on page 20.
WARNING If any of these conditions are not met,
the existing system must be updated
or replaced for that concern. Failure to
follow all instructions can result in flue gas
spillage and carbon monoxide emissions,
causing severe personal injury or death.

12
1 Determine water heater location
Combustion and ventilation air
requirements for appliances drawing air
from the equipment room
Provisions for combustion and ventilation air must be in
accordance with Air for Combustion and Ventilation, of the
latest edition of the National Fuel Gas Code, ANSI Z223.1, in
Canada, the latest edition of CGA Standard B149 Installation
Code for Gas Burning Appliances and Equipment, or
applicable provisions of the local building codes.
The equipment room MUST be provided with properly sized
openings to assure adequate combustion air and proper
ventilation.
Maintain minimum specified clearances for adequate
operation. All installations must allow sufficient space for
servicing the vent connections, water pipe connections,
piping and other auxiliary equipment, as well as the appliance.
Multiple appliances may be installed in a modular water
heater installation. Multiple appliances may be installed
side by side with no clearance between adjacent appliances
because this appliance is approved for zero clearance from
combustible surfaces.
Consult the Venting section of this manual for specific
installation instructions for the appropriate type of venting
system that you will be using.
Figure 1-3_Combustion Air Direct from Outside
1. If air is taken directly from outside the building
with no duct, provide two permanent openings to
the equipment room (see FIG. 1-3):
(a) Combustion air opening, with a minimum free area of
one square inch per 4000 Btu/hr input (5.5 cm2per
KW). This opening must be located within 12" (30 cm)
of the bottom of the enclosure.
(b) Ventilation air opening, with a minimum free area of
one square inch per 4000 Btu/hr input (5.5 cm2 per
kW). This opening must be located within 12" (30 cm) of
the top of the enclosure.
Figure 1-4_Combustion Air Through Ducts
2. If combustion and ventilation air is taken from the
outdoors using a duct to deliver the air to the
equipment room, each of the two openings should be
sized based on a minimum free area of one square inch
per 2000 Btu/hr (11 cm2per kW) of input (see FIG. 1-4).
Installation & Service Manual

13
1 Determine water heater location (continued)
Figure1-6_Combustion Air fromOutside-SingleOpening
3. If air is taken from another interior space, each of the
two openings specified above should have a net free
area of one square inch for each 1000 Btu/hr (22 cm2
per kW) of input, but not less than 100 square inches
(645 cm2) (see FIG. 1-5).
4. If a single combustion air opening is provided to bring
combustion air in directly from the outdoors, the opening
must be sized based on a minimum free area of one square
inch per 3000 Btu/hr (7 cm2per kW). This opening must
be located within 12" (30 cm) of the top of the enclosure
(see FIG. 1-6).
IF NECESSARY FOR
TIGHT CONSTRUCTION
Figure 1-5_Combustion Air from Interior Space
Installation & Service Manual
TABLE - 1B
MINIMUM RECOMMENDED COMBUSTION
AIR SUPPLY TO EQUIPMENT ROOM
Model
Number
FIG. 1-3 FIG. 1-4 FIG. 1-5 FIG. 1-6
*Outside Air from
2 Openings Directly from
Outdoors
*Outside Air from
2 Ducts Delivered from
Outdoors
**Inside Air from
2 Ducts Delivered from Interior
Space
*Outside Air from
1 Opening Directly
from Outdoors, in2
Top
Opening, in2
Bottom
Opening, in2
Top
Opening, in2
Bottom
Opening, in2
Top
Opening, in2
Bottom
Opening, in2
126-065 32
(207 cm2)
32
(207 cm2)
63
(407 cm2)
63
(407 cm2)
125
(807 cm2)
125
(807 cm2)
42
(271 cm2)
151-100 38
(246 cm2)
38
(246 cm2)
75
(484 cm2)
75
(484 cm2)
150
(968 cm2)
150
(968 cm2)
50
(323 cm2)
201-100 50
(323 cm2)
50
(323 cm2)
100
(646 cm2)
100
(646 cm2)
200
(1,291 cm2)
200
(1,291 cm2)
67
(433 cm2)
286-125 72
(465 cm2)
72
(465 cm2)
143
(923 cm2)
143
(923 cm2)
285
(1,839 cm2)
285
(1,839 cm2)
95
(613 cm2)
401-125 100
(646 cm2)
100
(646 cm2)
200
(1,291 cm2)
200
(1,291 cm2)
400
(2,581 cm2)
400
(2,581 cm2)
134
(865 cm2)
501-125 125
(807 cm2)
125
(807 cm2)
250
(1,613 cm2)
250
(1,613 cm2)
500
(3,226 cm2)
500
(3,226 cm2)
167
(1,078 cm2)
*Outside air openings shall directly communicate with the outdoors. When combustion air is drawn from the outside through a
duct, the net free area of each of the two openings must have twice (2 times) the free area required for Outside Air/2 Openings.
The above requirements are for the water heater only; additional gas fired appliances in the equipment room will require an
increase in the net free area to supply adequate combustion air for all appliances.
**Combined interior space must be 50 cubic feet per 1,000 Btu/hr input. Buildings MUST NOT be of *“Tight Construction”.
For buildings of *“Tight Construction”, provide air openings into the building from outside.
*No combustion air openings are needed when the water heater is installed in a space with a volume NO LESS than 50 cubic feet
per 1,000 Btu/hr of all installed gas fired appliances. Buildings MUST NOT be of *“Tight Construction”.
*“Tight Construction” is defined as a building with less than 0.40 ACH (air changes per hour).

1 Determine water heater location
14
The result is improper combustion and a non-warrantable,
premature appliance failure.
EXHAUST FANS: Any fan or equipment which exhausts air
from the equipment room may deplete the combustion air
supply and/or cause a downdraft in the venting system. Spillage
of flue products from the venting system into an occupied
living space can cause a very hazardous condition that must be
immediately corrected. If a fan is used to supply combustion
air to the equipment room, the installer must make sure that it
does not cause drafts which could lead to nuisance operational
problems with the appliance.
Combustion air requirements are based on the latest edition
of the National Fuel Gas Code, ANSI Z223.1; in Canada refer
to the latest edition of CGA Standard CAN B149.1. Check all
local code requirements for combustion air.
All dimensions based on net free area in square inches. Metal
louvers or screens reduce the free area of a combustion air
opening a minimum of approximately 25%. Check with
louver manufacturers for exact net free area of louvers.
Where two openings are provided, one must be within 12"
(30cm) of the ceiling and one must be within 12" (30cm) of
the floor of the equipment room. Each opening must have
net free area as specified in the chart above (Table 1B). Single
openings shall commence within 12" (30cm) of the ceiling.
CAUTION Under no circumstances should the
equipment room ever be under negative
pressure. Particular care should be taken
where exhaust fans, attic fans, clothes
dryers, compressors, air handling units,
etc., may take away air from the unit.
The combustion air supply must be completely free of any
flammable vapors that may ignite or chemical fumes which
may be corrosive to the appliance. Common corrosive chemical
fumes which must be avoided are fluorocarbons and other
halogenated compounds, most commonly present as refrigerants
or solvents, such as Freon, trichlorethylene, perchlorethylene,
chlorine, etc. These chemicals, when burned, form acids which
quickly attack the stainless steel heat exchanger, headers, flue
collectors, and the vent system.
Installation & Service Manual

15
IMG00464
Figure 2-1 Two-Pipe Sidewall Termination - See page
23 for more details
Direct venting options - Sidewall Vent
2 General venting
Installation & Service Manual
IMG00464
Figure 2-2 PVC/CPVC Concentric Sidewall Termination
- See page 27 for more details
IMG00466
Figure 2-3 Two-Pipe Vertical Termination
- See page 30 for more details
IMG00466
Figure 2-4 PVC/CPVC Concentric
Vertical Termination - See page 32
for more details
IMG00466
Figure 2-5 Vertical Vent, Sidewall
Air - See page 19 for more details
Direct venting options - Vertical Vent

16
2 General venting
Installation & Service Manual
This appliance requires a special venting
system. Use only approved stainless steel,
PVC, CPVC or polypropylene pipe and
fittings listed in Tables 2D, 2E, and 2G for
vent pipe, and fittings. Failure to comply
could result in severe personal injury,
death, or substantial property damage.
Installation must comply with local
requirements and with the National
Fuel Gas Code, ANSI Z223.1 for U.S.
installations or CSA B149.1 for Canadian
installations.
Install vent and combustion air piping
DANGER The Shield water heater must be vented and
supplied with combustion and ventilation
air as described in this section. Ensure the
vent and air piping and the combustion
air supply comply with these instructions
regarding vent system, air system, and
combustion air quality. See also Section 1
of this manual.
Inspect finished vent and air piping
thoroughly to ensure all are airtight and
comply with the instructions provided and
with all requirements of applicable codes.
Failure to provide a properly installed vent
and air system will cause severe personal
injury or death.
WARNING
NOTICE
WARNING For closet and alcove installations, CPVC,
polypropylene or stainless steel material
MUST BE used in a closet/alcove structure.
Failure to follow this warning could result
in fire, personal injury, or death.
Air intake/vent connections
1. Combustion Air Intake Connector (FIG. 2-6) - Used to
provide combustion air directly to the unit from outdoors. A
fitting is provided on the unit for final connection.
Combustion air piping must be supported per guidelines
listed in the National Mechanical Code, Section 305, Table
305.4 or as local codes dictate.
2. Vent Connector (FIG.'s 2-7 thru 2-9) - Used to provide a
passageway for conveying combustion gases to the
outside. A transition fitting is provided on the unit for
final connection. Vent piping must be supported per the
National Building Code, Section 305, Table 305.4 or as
local codes dictate.
The Shield water heater vent and air piping can be installed
through the roof or through a sidewall. Follow the procedures
in this manual for the method chosen. Refer to the information
in this manual to determine acceptable vent and air piping
length.
You may use any of the vent/air piping methods covered in this
manual. Do not attempt to install the Shield water heater using
any other means.
You must also install air piping from outside to the water
heater air intake adapter unless following the Optional Room
Air instructions on page 19 of this manual. The resultant
installation is direct vent (sealed combustion).
WARNING DO NOT mix components from different
systems. The vent system could fail,
causing leakage of flue products into the
living space. Mixing of venting materials
will void the warranty and certification of
the appliance.
WARNING Do not connect any other appliance to
the vent pipe or multiple water heaters to
a common vent pipe. Failure to comply
could result in severe personal injury,
death, or substantial property damage.
Improper installation of venting systems
may result in injury or death.
CAUTION
Follow the instructions in Section 1, page
11 of this manual when removing a water
heater from an existing vent system.
NOTICE
IMG00467
AIR
Figure 2-6 Near Water Heater Air Piping

17
2 General venting (continued)
Installation & Service Manual
Requirements for installation in
Canada
1. Installations must be made with a vent pipe system
certified to ULC-S636.
2. The first three (3) feet of plastic vent pipe from the
appliance flue outlet must be readily accessible for visual
inspection.
3. The components of the certified vent system must not be
interchanged with other vent systems or unlisted
pipe/fittings. For concentric vent installations, the inner
vent tube must be replaced with field supplied certifiedvent
material to comply with this requirement.
4. The 3" Concentric Vent Kit available from Lochinvar (see
Section 3 – Sidewall Termination – Optional Concentric
Vent) and the 3" Concentric Vent Kit available from IPEX
are both approved for use on the Shield water heater. Both
kits are listed to the ULC-S636 standard for use in Canada.
Minimum / Maximum allowable
combustion air and vent piping lengths
are as follows:
Combustion Air = 12 equivalent feet minimum / 100
equivalent feet maximum
Vent = 12 equivalent feet minimum / 100 equivalent feet
maximum
When determining equivalent combustion air and vent
length, add 5 feet for each 90° elbow and 3 feet for each 45°
elbow.
EXAMPLE: 20 feet of PVC pipe + (4) 90° elbows + (2) 45°
elbows + (1) concentric vent kit (CVK3003) = 49 equivalent
feet of piping.
The appliance output rating will reduce
by up to 1.5% for each 25 feet of vent
length.
NOTICE
Table 2B Concentric Vent Kit Equivalent Vent Lengths
Sizing
The Shield water heater uses model specific combustion air
intake and vent piping sizes as detailed in Table 2A below.
Table 2A Air Intake/Vent Piping Sizes
NOTICE
Model Air Intake Vent
126-065 -- 201-100 3 inches 3 inches
286-125 -- 501-125 4 inches 4 inches
Model Kit
Number Equivalent Vent Length
126-065 -- 201-100 CVK3003 3 feet
286-125 CVK3007 3 feet
401-125 CVK3007 5 feet
501-125 CVK3007 30 feet
Increasing or decreasing combustion air
or vent piping sizes is not authorized.

18
2 General venting
Installation & Service Manual
Materials
Air inlet pipe materials:
The air inlet pipe(s) must be sealed. Choose acceptable
combustion air inlet pipe materials from the following list:
PVC, CPVC, Polypropylene or ABS
Dryer Vent or Sealed Flexible Duct (not recommended
for rooftop air inlet)
Galvanized steel vent pipe with joints and seams sealed as
specified in this section.
Type “B” double-wall vent with joints and seams sealed as
specified in this section.
AL29-4C, stainless steel material to be sealed to
specification of its manufacturer.
*Plastic pipe may require an adapter (not provided) to
transition between the air inlet connection on the appliance
and the plastic air inlet pipe.
WARNING Using air intake materials other than
those specified can result in personal
injury, death or property damage.
NOTICE The use of double-wall vent or insulated
material for the combustion air inlet pipe is
recommended in cold climates to prevent
the condensation of airborne moisture in
the incoming combustion air.
Sealing of Type “B” double-wall vent material or galvanized
vent pipe material used for air inlet piping on a sidewall or
vertical rooftop Combustion Air Supply System:
a. Seal all joints and seams of the air inlet pipe using either
Aluminum Foil Duct Tape meeting UL Standard 723 or
181A-P or a high quality UL Listed silicone sealant such as
those manufactured by Dow Corning or General Electric.
b. Do not install seams of vent pipe on the bottom of
horizontal runs.
c. Secure all joints with a minimum of three (3) sheet metal
screws or pop rivets. Apply Aluminum Foil Duct Tape or
silicone sealant to all screws or rivets installed in the vent
pipe.
d. Ensure that the air inlet pipes are properly supported.
The PVC, CPVC, or ABS air inlet pipe should be cleaned and
sealed with the pipe manufacturer’s recommended solvents
and standard commercial pipe cement for the material used.
The PVC, CPVC, ABS, Dryer Vent or Flex Duct air inlet pipe
should use a silicone sealant to ensure a proper seal at the
appliance connection and the air inlet cap connection. Dryer
vent or flex duct should use a screw type clamp to seal the vent
to the appliance air inlet and the air inlet cap. Proper sealing
of the air inlet pipe ensures that combustion air will be free of
contaminants and supplied in proper volume.
Follow the polypropylene manufacturer’s instructions when
using polypropylene material as an inlet pipe.
When a sidewall or vertical rooftop combustion air supply
system is disconnected for any reason, the air inlet pipe must
be resealed to ensure that combustion air will be free of
contaminants and supplied in proper volume.
DANGER Failure to properly seal all joints and seams
as required in the air inlet piping may
result in flue gas recirculation, spillage
of flue products and carbon monoxide
emissions causing severe personal injury
or death.

19
2 General venting (continued)
Installation & Service Manual
Air contamination
Pool and laundry products and common household and hobby
products often contain fluorine or chlorine compounds. When
these chemicals pass through the water heater, they can form
strong acids. The acid can eat through the water heater wall,
causing serious damage and presenting a possible threat of flue
gas spillage or water heater water leakage into the building.
Please read the information given in Table 1A, page 10, listing
contaminants and areas likely to contain them. If contaminating
chemicals will be present near the location of the water heater
combustion air inlet, have your installer pipe the water heater
combustion air and vent to another location, per this manual.
If the water heater combustion air inlet is
located in a laundry room or pool facility,
for example, these areas will always contain
hazardous contaminants.
To prevent the potential of severe personal
injury or death, check for areas and products
listed in Table 1A, page 10 before installing
the water heater or air inlet piping.
If contaminants are found, you MUST:
• Remove contaminants permanently.
—OR—
• Relocate air inlet and vent terminations
to other areas.
WARNING
WARNING
Optional room air
WARNING When utilizing the single pipe method,
provisions for combustion and ventilation
air must be in accordance with Air for
Combustion and Ventilation, of the latest
edition of the National Fuel Gas Code,
ANSI Z223.1, in Canada, the latest edition
of CGA Standard B149 Installation
Code for Gas Burning Appliances and
Equipment, or applicable provisions of
the local building codes.
Commercial applications utilizing the Shield water heater
may be installed with a single pipe carrying the flue products
to the outside while using combustion air from the equipment
room. In order to use the room air venting option the
following conditions and considerations must be followed.
• The unit MUST be installed with the appropriate
room air provisions.
• The equipment room MUST be provided with
properly sized openings to assure adequate
combustion air. Please refer to instructions provided
with the room air kit (KIT30052 - Models 126-065
-- 201-100 and KIT30053 - Models 286-125 -- 501-
125).
• There will be a noticeable increase in the noise level
during normal operation from the inlet air opening.
• Using the room air configuration makes the unit
vulnerable to combustion air contamination from
within the building. Please review Section 1,
Prevent Combustion Air Contamination, to ensure
proper installation.
• Vent system and terminations must comply with the
standard venting instructions set forth in this
manual.
NOTICE Optional room air is intended for
commercial applications. Combustion
air piping to the outside is recommended
for residential applications.

20
2 General venting
Installation & Service Manual
Installing vent and air piping
Use only cleaners, primers, and solvents
that are approved for the materials which
are joined together.
NOTICE
1. Work from the water heater to vent or air termination.
Do not exceed the lengths given in this manual for the
air or vent piping.
2. Cut pipe to the required lengths and deburr the inside
and outside of the pipe ends.
3. Chamfer outside of each pipe end to ensure even
cement distribution when joining.
4. Clean all pipe ends and fittings using a clean dry rag.
(Moisture will retard curing and dirt or grease will
prevent adhesion.)
5. Dry fit vent or air piping to ensure proper fit up before
assembling any joint. The pipe should go a third to
two-thirds into the fitting to ensure proper sealing after
cement is applied.
6. Priming and Cementing:
a. Handle fittings and pipes carefully to prevent
contamination of surfaces.
b. Apply a liberal even coat of primer to the fitting
socket and to the pipe end to approximately 1/2"
beyond the socket depth.
c. Apply a second primer coat to the fitting socket.
d. While primer is still wet, apply an even coat of
approved cement to the pipe equal to the depth of
the fitting socket along with an even coat of
approved cement to the fitting socket.
e. Apply a second coat of cement to the pipe.
f. While the cement is still wet, insert the pipe into
the fitting, if possible twist the pipe a 1/4 turn as
you insert it. NOTE: If voids are present,
sufficient cement was not applied and joint could
be defective.
g. Wipe excess cement from the joint removing ring
or beads as it will needlessly soften the pipe.
PVC/CPVC
Table 2D PVC/CPVC Vent Pipe, and Fittings
All PVC vent pipes must be glued, properly
supported, and the exhaust must be pitched
a minimum of a 1/4 inch per foot back to
the water heater (to allow drainage of
condensate).
NOTICE
WARNING The vent connection to the appliance must
be made with the starter CPVC pipe section
provided with the appliance if PVC/CPVC
vent is to be used. The field provided
vent fittings must be cemented to the
CPVC pipe section using an “All Purpose
Cement” suitable for PVC and CPVC pipe.
Use only the vent materials, primer, and
cement specified in Table 2D to make
the vent connections. Failure to follow
this warning could result in fire, personal
injury, or death.
WARNING Insulation should not be used on PVC
or CPVC venting materials. The use of
insulation will cause increased vent wall
temperatures, which could result in vent
pipe failure.
Approved PVC/CPVC Vent Pipe and Fittings
Item Material Standard
Vent pipe PVC Schedule 40, 80 ANSI/ASTM D1785 PVC - DWV ANSI/ASTM D2665
CPVC Schedule 40, 80 ANSI/ASTM F441
Vent fittings PVC Schedule 40 ANSI/ASTM D2466 PVC Schedule 80 ANSI/ASTM D2467
CPVC Schedule 80 ANSI/ASTM F439
Pipe Cement
/ Primer PVC ANSI/ASTM D2564
CPVC ANSI/ASTM F493
NOTICE: DO NOT USE CELLULAR (FOAM) CORE PIPE
Figure 2-7 Near Water Heater PVC/CPVC Venting
This product has been approved for use with the PVC/CPVC
vent materials listed in Table 2D.
NOTE: In Canada, CPVC and PVC vent pipe, fittings and cement/
primer must be ULC-S636 certified.
MODELS: 126-065 - 201-100
MODELS: 286-125 - 501-125
VENT
VENT
IMG00468