Laars MSTWW199 User manual

H2372600E
WARNING
If the information in this manual is not
followed exactly, a re or explosion may
result causing property damage, personal
injury or loss of life.
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
nearby phone. Follow the gas supplier's
instructions.
• If you cannot reach your gas supplier, call
the re department.
Installation and service must be performed
by a qualied installer, service agency, or gas
supplier.
FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,
qualied in hot water boiler and heater installation and maintenance. Improper installation and/or operation
could create carbon monoxide gas in ue gases which could cause serious injury, property damage, or
death. Improper installation and/or operation will void the warranty.
AVERTISSEMENT
Assurez-vous de bien suivres les instructions
données dans cette notice pour réduire au
minimum le risque d’incendie ou d’explosion
ou pour éviter tout dommage matériel, toute
blessure ou la mort.
Ne pas entreposer ni utiliser d’essence ou ni
d’autres vapeurs ou liquides inammables dans
le à proximité de cet appareil ou de tout autre
appareil.
QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE
GAZ:
• Ne pas tenter d’allumer d’appareils.
• Ne touchez à aucun interrupteur. Ne pas vous servir
des téléphones dans le bâtiment où vous vous
trovez.
• Appelez immédiatement votre fournisseur de
gaz depuis un voisin. Suivez les instructions
du fournisseur.
• Si vous ne pouvez rejoindre le fournisseur de
gaz, appelez le sservice des incendies.
L’installation et l’entretien doivent être assurés par
un installateur ou un service d’entretien qualié
ou par le fournisseur de gaz.
Installation and Operation
Instructions for
MASCOT ® ST
Wall-Mounted, Modulating
Gas Condensing Water Heater
Model MSTWW
199,000 BTU/hr
• Natural Gas (NG) - Factory Conguration
• Propane Gas (LP) - Factory Conguration
Installation and Operation Instructions Document 1316E

TABLE OF CONTENTS
SECTION 1 Product Accessories
1.1 Introduction ...........................................................3
1.2 Included with the Unit ...........................................3
SECTION 2 Product Characteristics
2.1 Model Nomenclature ............................................4
2.2 Specications .......................................................5
2.3 Dimensions ...........................................................6
2.4 Names of Components .........................................7
SECTION 3 Safety Regulations
3.1 Safety Symbols ....................................................8
3.2 Safety Precautions and Proper Use .....................9
SECTION 4 Installation
4.12 Gas High Altitude Setting ..................................30
4.13 Gas Conversion ..................................................30
4.14 Plumbing Guidelines. ...................................31
4.15 Disposal of Condensate .....................................33
4.16 Pressure Relief Valve .........................................34
4.17 Electrical Wiring Connections .............................34
4.18 DIP Switches .....................................................35
4.19 Wiring Diagram ..................................................36
4.20 Ladder Diagram .................................................37
4.21 Electrical Connections .......................................38
SECTION 5 Control Display and Operation
5.1 Control Dial and Buttons ....................................39
5.2 LCD Overview ...................................................41
5.3 Operating Mode ..................................................42
5.4 Status Display Mode ..........................................43
5.5 DHW Set Point Change Mode ...........................44
5.6 Installer Mode ....................................................45
5.7 Error Mode .........................................................46
SECTION 6 Error Codes
6.1 Error Codes .......................................................47
6.2 Fault Tree Analysis ............................................50
6.2.1 Flame Detection .................................................50
6.2.2 Gas Detection .....................................................50
6.2.4 ‘I/T’, ‘DHW’, ‘OP’ Sensor detects ........................51
6.2.3 Fan / Air Proving .................................................51
SECTION 7 Troubleshooting
7.1 Diagnostics .........................................................52
SECTION 8 Maintenance
8.1 Annual Startup and General Maintenance .........55
SECTION 9 Installation Check
9.1 Quick View .........................................................58
9.2 Final check lists ..................................................58
SECTION 10 Repair Part List and Diagrams
10.1 Parts List ............................................................60
LAARS Heating Systems
NOTE: For Cascading Installations, please refer
to document 1351 ‘Cascading the Mascot ST’,
available online.
4.1 Location and Clearances ....................................12
4.2 Wall Mount Bracket ............................................13
4.2.1 The installation height and location ...................13
4.2.2 Hang the Water Heater.......................................13
4.3 Combustion Air ...................................................14
4.3.1 Combustion Air from Room ................................14
4.3.2 Ducted Combustion Air .......................................14
4.4 Venting (Exhaust) ...............................................16
4.5 General Location Guideline ................................17
4.6 Locations for Vent Pipe Terminator ....................18
4.6.1 Direct Venting Clearances .................................18
4.6.2 Non-Direct Venting Clearances .........................19
4.6.3 Venting Requirements in the
Commonwealth of Massachusetts .....................20
4.6.4 Common Vent Test .............................................21
4.7 Air Supply and Vent Connections .......................22
4.7.1 Vent / Air Pipe Lengths .......................................22
4.7.2 Direct Venting .....................................................22
4.7.3 Single Venting ...................................................23
4.8 Vent / Air Pipe Termination .................................23
4.9 Gas Supply and Piping .......................................26
4.10 Gas Supply Pressure .........................................29
4.11 Gas Setup and Adjustment .................................29

Mascot ST Tankless Water Heater Page 3
SECTION 1 Product Accessories
Items Descriptions Qty
LAARS Tankless Water Heater 1
Installation Instructions and
User’s Manual 1
Condensate Hose 1
Wall Mount Bracket 1
Bolts w/Anchors 4
Vent terminal cap 3” 2
Parts Kit 1
1.1 Introduction
This manual provides information necessary for the
installation, operation, and maintenance of the LAARS
Heating Systems Mascot ST. All application and installation
procedures must be read and reviewed completely before
proceeding with the installation. Consult the LAARS Heating
Systems factory, or your local factory representative, with any
problems or questions regarding this equipment. Experience
has shown that most operating problems are caused by
improper installation.
All installations must be made in accordance with
1) American National Standard Z223.1/NFPA54-Latest
Edition “National Fuel Gas Code” or
2) CSA B149.1 “Natural Gas and Propane Installation Code” and
with the requirement of the local utility or other authorities having
jurisdiction. Such applicable requirements take precedence over the
general instructions contained herein.
All electrical wiring is to be done in accordance with the local
codes, or in the absence of local codes, with: 1) The National
Electrical Code ANSI/NFPA No. 70-latest Edition, or 2) CSA STD.
C22.1 “Canadian Electrical Code - Part 1”. This appliance must be
electrically grounded in accordance with these codes.
1.2 Included with the Unit

LAARS Heating Systems
Page 4
2 3 4 5 6 7 8 9 10 11 12 13
S T W W 1 9 9 A 1 X
SERIES
Mascot ST W - Condensing
Water
Heater
SIZE
MBTU/h
199
FUEL
N - Natural
P - Propane
CONFIG
W -Wall Hung
ALTITUDE
A - 0-10,000 Feet
REVISION
1 - First
OPTIONS
X - Standard
R - Recirculation
PUMP
X - no Pump
1
M
SECTION 2 Product Characteristics
2.1 Model Nomenclature
The Model Nomenclature is shown on your Rating Plate
and consists of a series of letters and numbers
( Nomenclature ) that further identies the
characteristics of your Mascot ST.
MODEL NUMBER

Mascot ST Tankless Water Heater Page 5
Model Name MSTWW199
Gas Input Rate MAX 199,000 Btu/h
MIN 19,900 Btu/h
Hot Water Capacity
35°F Rise 11.0 GPM
45°F Rise 8.5 GPM
77°F Rise 5.0 GPM
Installation Indoor Wall Hung
Flue System Sealed Combustion Direct & Single Vnet
Vent Run 2″(50ft) / 3″(100ft) Schedule 40 PVC, CPVC, PP, ABS
Gas Supply Pressure NG 3.5˝ WC to 10.5˝ WC
LP 8.0˝ WC to 13.0˝ WC
Manifold Pressure Gas Type NG LP
MAX Fire
-0.11” to -0.17” WC -0.07” to -0.11” WC
MIN Fire
-0.10” to -0.16” WC -0.06” to -0.10” WC
Power Supply
Main Supply 120V 60Hz / 4A
Maximum
Power Consumption 135W(82W+53W_Ceramic heater)
Ignition System Direct Electronic Ignition / Automatic Flame Sensing
Burner System Single Orice Premixed Fuel Modulation Metal Fiber Infrared
Gas Valve System Air ratio valve
Minimum Flow Rate 0.5 GPM
Internal Pipe Material STS 304
Dimensions W17.3 ″ – H28.7 ″ – D14.8 ″
Product Weight 88 lbs ( 40 kg )
Shipping Weight 100 lbs ( 45 kg )
Sub Heat Exchanger Water Capacity Under 2 Gallon
Control Panel / Main Controller P-920C / GTH-9500C
Water Pressure MAX Hot water 150 psi
MIN 15 psi
Connection Sizes
Cold Water Inlet /
Hot Water Outlet 3/4″NPT
Gas Inlet 3/4″NPT
Materials Casing Cold Rolled Carbon Steel
Heat Exchanger Primary Heat Exchanger : STS 304
Secondary Heat Exchanger : STS 304
Safety Devices
Flame Rod, Overheat Cut O󰀨 Limit Switch , Gas Leak Detector
sensor, Exhaust Temperature High Limit Switch, Water Tem-
perature High Limit Switch, Frost Protection Ceramic Heater
2.2 Specications
• Temperature
Operating ambient Temperature Range : -10 to 60°C.
Operating Relative Humidity up to: 90% at 40°C.
Shipping & Storage Temperature Range of : -20 to 80°C.

LAARS Heating Systems
Page 6
Description Diameter
A
Vent Pipe Collar
3"
B
Air Intake Collar
3"
CGas Inlet 3/4"
D DHW Outlet 3/4"
EDHW Inlet 3/4"
FCondensate Drain 1/2"
GCold Water Inlet Filter _
2.3 Dimensions
Air Intake
Vent

Mascot ST Tankless Water Heater Page 7
2.4 Names of Components
# Name of Component
1
Vent Pipe Collar
2
Combustion Air Intake Assembly
3
Air Gas Mixture (AGM) Actuator
4
Ignition Transformer
5
Igniter
6
Operating Temperature Sensor
7
Switch High Limit
8
Sight Glass
9
Primary Heat Exchanger
11
Mixing Valve
12
Frost Protection
13
Air Pressure Switch
14
Gas Inlet
15
Gas Inlet Pipe
16
Freeze Protector Sensor
17
Domestic Hot Water (DHW) Outlet
18
Condensate Trap Cleanout
# Name of Component
19
Cold Water Inlet
20
Cold Water Inlet Filter
21
Manual Power Switch
22
DHW Temperature Sensor
23
Water Adjustment Valve
24
Condensate Trap Hose
25
Main Controller
26
Control Panel
27
Secondary Heat Exchanger
28
Flame Detection Sensor
29
Burner Case
30
Burner Overheat Switch
31
Gas Valve
32
Venting (exhaust) Duct
33
Gas Manifold
34
Blower
35
Air Intake Collar
Vent Combustion
Air

LAARS Heating Systems
Page 8
SECTION 3 Safety Regulations
3.1 Safety Symbols
WARNING WARNING
To avoid product damage, personal injury, or even
possible death, carefully read, understand, and
follow all the instructions in the Installation and
Operation manual before installation, operation
and service the Water Heater.
Laars cannot anticipate every circumstance
that might involve a potential hazard. Therefore,
all possible incidents are not included in our
warnings. Proper installation, operation, and
service are your responsibility.
You must make sure that the operation and
settings of the Water Heater are safe for you and
for others.
This manual provides Safety Symbols. When the
user fails to adhere to the following requirement,
it may cause death, serious injury, and substantial
property damage.
For safety symbols, ‘DANGER’, ‘WARNING’,
CAUTION’ are indicated and the denitions for these
terms are as follow:
DANGER
Indicates an imminently hazardous situation
which, if not avoided, will result in death or
serious injury. This signal word is limited to the
most extreme situations.
WARNING
Indicates a potentially hazardous situation
which, if not avoided, could result in death or
serious injury.
WARNING
Cancer and Reproductive Harm.
www.P65WARNINGS.CA.GOV. as required
by the state of California Proposition 65.
CAUTION
Indicates a potentially hazardous situation
which, if not avoided, may result in minor or
moderate injury. It is also used to alert against
unsafe practices and hazards involving only
property damage.
FOR YOUR SAFETY READ BEFORE
OPERATING
If you do not follow these instructions exactly, a re
or explosion could result causing property dam-
age, personal injury or loss of life.
A. This appliance does not have a pilot. It
is equipped with an ignition device which
automatically lights the burner. Do not try to
light the burner by hand.
B. BEFORE OPERATING smell all around the
appliance area for gas. Be sure to smell next
to the oor because some gas is heavier than
air and will settle on the oor.
WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electric switch; do not use any
phone in your building.
• Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s
instructions.
• If you cannot reach your gas supplier, call the
re department.
C. Use only your hand to push in or turn the gas
control knob. Never use tools. If the knob will
not push in or turn by hand, don’t try to repair
it, call a qualied service technician. Force
or attempted repair may result in a re or
explosion.
D. Do not use this appliance if any part has
been under water. Immediately call a qualied
service technician to inspect the appliance and
to replace any part of the control system and
any gas control which has been under water.
This appliance must be installed in accordance with
local codes if any; if not, follow ANSI Z224.1/NFPA
54 or CAN/CSA B149.1, Natural Gas and Propane
Installation Code, as applicable.
This appliance is certied for use at altitudes up
to 4,500ft(1,370m) in accordance to the latest CSA/
CGA 2.17-M91 Gas-Fired Appliances for Use at
High Altitudes.

Mascot ST Tankless Water Heater Page 9
DANGER
Vapors from ammable liquids will explode and
catch on re. These will cause death or severe
burns.
Do not use or store ammable products such as
gasoline, solvents or adhesives in the same room
or area near the appliance.
Keep ammable products
Far away from water heater
In approved containers
Tightly closed
Out of children’s reach
Vapors
Cannot be seen
are heavier than air
spread on the oor
Can spread from other rooms to the main burner
by air currents
Do not install the appliance where ammable
products will be stored.
Read and follow water heater warnings and
instructions thoroughly. If owner’s manual is
missing, contact the retailer or manufacturer.
The Laars Water Heater must be installed by a
qualied plumber, a licensed gas tter, and/or a
professional service technician.
Improper installation and/or operation will cause a
potentially hazardous situation, such as serious injury
or death. Also, it will void the warranty.
• The National Fuel Gas Code NFPA 54 / ANSI Z224.1
• National Electric Code ANSI/NEPA 70
• All applicable local, state, national and provincial
codes, regulations and laws.
Proper care is your responsibility. Carefully read and
understand the Operating Information in this manual
before operating the Laars Water Heater.
Be aware of the location of the gas shut-o󰀨 valve
and operation method. Close the gas shut-o󰀨 valve
immediately if the appliance is subjected to re,
overheating, ood, physical damage, or any other
damaging condition that might a󰀨ect the operation of
the unit. Water Heater must be checked by a qualied
technician before resuming operation.
DO NOT use this Water Heater if any part has been
under water. Immediately call a qualied technician
for inspecting the Water Heater and replacing any
part of the control system and gas control which have
been under water.
Do not power up the unit until the gas and water
supply valves are fully opened. Make sure that the
fresh air intake port and exhaust gas port are opened
and functional.
DO NOT attempt to install, repair, or service this
Water Heater by yourself.
Do not change any part of the Water heater.
Contact a qualied technician if the Water Heater
needs repair or maintenance.
Ask your gas supplier for a list of qualied service
providers.
DO NOT use spray paint, hair spray, or any other
ammable spray near Water Heater or near the
exterior fresh air inlet port. DO NOT place any items
in or around the exterior exhaust gas outlet port and/
or fresh air inlet port. These could restrict or block the
ow in or out of the vent system.
“Caution: While repairing control, all wires are
labeled. You must connect the wires in accordance
with the instruction.
Wiring errors can cause improper and dangerous
operation.
“Verify proper operation after servicing operation”
This consists of the gas ignition system components
which are protected from water (dripping, spraying, rain,
etc.) during operation and service (circulator replacement,
condensate trap, control replacement, etc.).
After installing the heater, safety device must be
tested.
This water heater is equipped with a blocked vent
shuto󰀨 system.
If the error code ‘41’ occurs, follow the instructions
below.
- First, turn o󰀨 the manual gas valve.
- Make sure that there is no foreign object in the vent
passage or rodent screen.
- If you do not nd any problem, do the following.
- Turn o󰀨 the error state by pressing the power button
of control panel.
- If the error occurs repeatedly, call your service
technician or gas supplier.

LAARS Heating Systems
Page 10
Before Operation
1. Check the Gas Type (NG/LP)
When using or moving the unit for the rst time, check
if gas type matches with the gas type of the Water
Heater. Check whether the gas type which is supplied
is NG (Natural Gas) or LP (Propane) and also check
the Water Heater gas type.
The gas type is indicated on the rating plate on side of
the Water Heater.
2. Check the Power (120V 60Hz)
Check that the appliance is connected properly.
3. Check the Cold Water
Inlet valve. Please keep the
appliance water inlet valve
open at all times. The appliance
will not ignite when insu󰀩cient
water or no water is in the
heating pipes.
4. Check the Gas Valve
Check that the manual gas shut-o󰀨 valve
that supplies the Mascot ST is opened.
5. Check the area around the appliance and remove
any combustible or ammable materials. Remove
laundry or any other items that are on or near the
water heater or exhaust vent.
open
When in Operation
CAUTION
1. Caution for Gas leak
Frequently check for a gas leak at the gas connection
portion with soapy water.
2. Caution for Ventilation
Make sure that there is su󰀩cient inow and outow of air
ventilation while using the unit.
If the ventilation is improper, combustion quality may
deteriorate inside the appliance and cause shortened life
of the appliance.
3. Burn Warning
Be careful not to burn yourself on the ue or pipes. They
become extremely hot during operation.
3.2 Safety Precautions and Proper Use

Mascot ST Tankless Water Heater Page 11
WARNING
Donot usetheappliance foranyother purposethan forheating
andhot water.
Do not store combustibles or ammable material such as
gasolinenear theappliance.
Donot storeotheritemson ornearthis waterheater.
Do not store combustible (ammable) materials such as papers.
Do not hang clothes on the exhaust stack. This may start a re.
Gas leakage test.
Gas supply line must be inspected regularly.
Do not shut o󰀨 the Water Heater.
When you leave home for a long time, do not shut
o󰀨 Water Heater. The Water Heater has a freeze
protection function. The ceramic heater is installed
inside of the heater’s internal pipe to protect the
heater from freezing.
Do not wipe the appliance or control panel with
wet cloth. Electric shock may occur, or internal parts
may fail due to the exposure to moisture.
Do not disassemble the Water Heater.
If repair is required, call your local qualied
technician.
After repair of gas pipeline or gas regulator
replacement, call a qualied contractor for inspection
before starting it up.
Carbon monoxide poisoning
If exhaust fumes enter the room, it could cause
poisoning by carbon monoxide gas. Check that the
exhaust tubes are properly connected. Open windows
for ventilation. Call a qualied service technician for
immediate repair.
Steps to take if you have a Gas leak.
1. Shut down the water heater as soon as gas fumes
are detected.
2. Close the intermediate gas valve.
3. Open windows for ventilation.
4. Call a qualied service technician for immediate
repair.
CAUTION
Scalding Risk: Manufacturer
strongly recommends the
use of an anti-scald mixing
valve at domestic hot water
outlet (boiler location) to
reduce potential for scalding.
Contact Manufacturer for
recommended models.
Check with local codes.
__________________________________________

LAARS Heating Systems
Page 12
SECTION 4 Installation
4.1 Location and Clearances
The Mascot ST must be mounted to a suitable wall by
a qualied heating contractor under the guidelines of a
wall mounted water heater.
The wall may be of concrete or wood. Suitable fasteners
for concrete or wood must be used. Failure to wall
mount this water heater using correct fasteners will
a󰀨ect the performance and life expectancy of the water
heater and will void the warranty.
9
23
3
8
3
8
6
15
12
30
Table 1. Minimum Clearances
Installations must comply with
• All the local, state, provincial, and national codes,
laws, regulations and ordinances.
• National Fuel Gas Code, ANSI Z224.1 – The latest
version.
• National Electrical Code.
• A National Standard of Canada CAN/CSA-B149.1-05
Check before placing the Water Heater
• Always check the connected components which are
near to the heater. The components are below.
Water piping position / Venting adapter / Gas supply
piping / Electrical power / Condensate drain hose.
• Conrm area around Water Heater. Remove any
combustible materials, gasoline and other ammable
liquids. Failure to keep Water Heater area clear and
free of combustible materials, gasoline and other
ammable liquids and vapors can result in severe
personal injury, death or substantial property damage.
• The Water Heater which has gas control system
components must be protected from any possible
danger during operation and service.
• If new Water Heater replaces the existing appliance,
check and correct system problems, for example:
- Do not install : System leaks causing oxygen
corrosion or heat exchanger cracks from hard water
deposits.
Provide clearances as outlined in Table 1
• As for vent connector and hot water pipe from
combustible construction, please consult with a
qualied technician.
• If the heater was installed in a narrow space or
corner, please ensure that there is su󰀩cient space
for service and maintenance access. For regular
maintenance, there should not be any problem to
approach gas and water line.
The water heater must be installed on a wall that can
bear its weight.
WARNING
WARNING
CLEARANCES FOR SERVICE ACCESS
• The water heater must be installed on a wall that
can bear its weight.
• Adequate service clearance must be considered.
• The Water heater can be installed on any suitable
internal wall (sound proong may be required when
installing onto a stud partition wall).
Minimum clearances to Combustibles.
to Combustibles and for Service.
For installation from
Non-Combustibles and
Combustibles
Suggested Service
Clearance
TOP 9 in (23 cm) 18 in (46 cm)
BACK 5/8 in (1.5 cm) 5/8 in (1.5 cm)
FRONT 6 in (15 cm) 40 in (101 cm)
SIDE 3 in (7 cm) 8 in (20 cm)
BOTTOM 12 in (30 cm) 24 in (61 cm)
NOTE: For Cascading Installations, please refer
to document 1351 ‘Cascading the Mascot ST’,
available online.

Mascot ST Tankless Water Heater Page 13
4.2 Wall Mount Bracket
4.2.1 The installation height and location
The installation height depends on your installation scenario.
With all clearances considered, and given adequate positioning
for air supply and venting, you will need to determine the
best position to mount the Wall Mount Bracket. The wall
must be concrete, wood, or plywood over studs, and
must be strong enough to hold the water heater!
• Start by familiarizing yourself to how the
included Wall Mount Bracket hooks underneath
the two Hangers that are attached to the back of
the water heater. The ‘hooks’ of the Wall Mount Bracket
will be 3” from the Top of the water heater once the water
heater is hung.
• Position the Wall Mount Bracket at the location that it will go,
being sure that it is level, and then drill 4 holes (0.47”dia)
with a 1/2” drill bit, into the wall through the Bracket.
• If mounting to a concrete wall, then use the concrete anchors. If
onto wood or 5/8” (16 mm) plywood, then use the wood screws.
Do not hang the Mascot ST onto
sheetrock unless it is possible to
fasten directly into the structural
studs. If the included anchors
do not suit your installation,
you must use ‘Field Supplied’
anchors that are appropriate
for the wall’s construction.
Wall Mount
Bracket
Bolts (4) Wall Mount
Bracket
Anchors*
(4)
3" to Top
of Unit
Concrete,
Wood,
or 5/8" Plywood
4.2.2 Hang the Water Heater
• Lift the water heater up, align the Hangers
on the back of the water heater with the hooks
on the Wall Mount Bracket, and hang the water
heater onto the Wall Mount Bracket. Do a visual
inspection to make sure that the water heater
is hanging properly onto the hooks of the Wall
Mount Bracket.
• Fasten the bottom of the water heater to the
wall using 2 suitable wall anchors (eld supplied).
Hangers (2)
(fastened to the back of unit)

LAARS Heating Systems
Page 14
Table 2. Required Combustion Air Pipe Material.
COMBUSTION AIR INSTALLATION STANDARDS
MATERIAL UNITED STATES CANADA
ABS ANSI/ASTM D1527
PVC, sch 40 ANSI/ASTM D1785 or D2665 Air pipe material must be chosen
CPVC, sch 40 ANSI/ASTM F441 CPVC, sch 40, ANSI/ASTM, Polypropylene
Polypropylene UL1738, ULC S636. based upon the intended application of the water heater.
Single wall galv. steel 26 gauge
SECTION 4. Installation (continued)
4.3 Combustion Air
Mascot ST water heaters must have provisions for
combustion and ventilation air in accordance with the
applicable requirements for Combustion Air Supply and
Ventilation in the National Fuel Gas Code, ANSI Z223 1;
or in Canada, the Natural Gas and Propane Installation
Code, CSA B149.1. All applicable provisions of local
building codes must also be adhered to.
A Mascot ST unit can take combustion air from the
space in which it is installed, or the combustion air
can be ducted directly to the unit. Ventilation air
must be provided in either case.
4.3.1 Combustion Air from Room
In the United States, the most common requirements
specify that the space shall communicate with the
outdoors in accordance with method 1 or 2, which follow.
Where ducts are used, they shall be of the same cross-
sectional area as the free area of the openings to which
they connect.
Method 1: Two permanent openings, one commencing
within 12” (300mm) of the top and one commencing
within 12” (300mm) of the bottom, of the enclosure
shall be provided. The openings shall communicate
directly, or by ducts, with the outdoors or spaces
that freely communicate with the outdoors. When
directly communicating with the outdoors, or when
communicating to the outdoors through vertical ducts,
each opening shall have a minimum free area of 1
square inch per 4000 Btu/hr (550 square mm/kW) of
total input rating of all equipment in the enclosure. When
communicating to the outdoors through horizontal ducts,
each opening shall have a minimum free area of not
less than 1 square inch per 2000 Btu/hr (1100 square
mm/kW) of total input rating of all equipment in the
enclosure.
Method 2: One permanent opening, commencing
within 12” (300mm) of the top of the enclosure, shall
be permitted. The opening shall directly communicate
with the outdoors or shall communicate through a
vertical or horizontal duct to the outdoors or spaces
that directly communicate with the outdoors and shall
have a minimum free area of 1square inch per 3000
Btu/hr (734 square mm/kW) of the total input rating of
all equipment located in the enclosure. This opening
must not be less than the sum of the areas of all vent
connectors in the conned space.
Other methods of introducing combustion and
ventilation air are acceptable, providing they conform to
the requirements in the applicable codes listed above.
In Canada, consult local building and safety codes or, in
absence of such requirements, follow CAN/CGA B149.
4.3.2 Ducted Combustion Air
The combustion air can be taken through the wall, or
through the roof. When taken from the wall, it must
be taken from out-of-doors by means of the LAARS
horizontal wall terminal. When taken from the roof, a
eld-supplied rain cap or an elbow arrangement must
be used to prevent entry of rain water.
Use ABS, PVC, CPVC, polypropylene, or galvanized
pipe for the combustion air intake. Route the intake to
the water heater as directly as possible. Seal all joints.
Provide adequate hangers. The unit must not support
the weight of the combustion air intake pipe. Maximum
linear pipe length allowed is shown in Table 6. Subtract
5 allowable linear ft. (1.5m) for every elbow used.
The connection for the intake air pipe is at the top of
the unit.
In addition to air needed for combustion, air shall also
be supplied for ventilation, including air required for
comfort and proper working conditions for personnel.

Mascot ST Tankless Water Heater Page 15
NOTICE
The instructions for the installation of the venting
system shall specify that the horizontal portions of
the venting system shall be supported to prevent
sagging; the methods of and intervals for support
shall be specied. These instructions shall also
specify that the venting system:
Category I, II and IV water heaters must be installed
so that horizontal sections have a slope of at least ¼
inch per foot (21 mm/m) to prevent accumulation of
condensate; and
For Category II and IV water heaters, where
necessary, have means provided for drainage of
condensate.
AVIS
Les instructions d'installation du système
d'évacuation doivent préciser que les sections
horizontales doivent être supportées pour prévenir
le échissement. Les méthodes et les intervalles
de support doivent être spéciés. Les instructions
doivent aussi indiquer les renseignements suivants:
les chaudières de catégories I, II et IV doivent
présenter des tronçons horizontaux dont la pente
montante est d'au moins ¼ po par pied (21 mm/m)
entre la chaudière et l'évent; les chaudières de
catégories II et IV doivent être installées de façon à
empêcher l'accumulation de condensat;
et si nécessaire, les chaudières de catégories II et IV
doivent être pourvues de dispositifs d'évacuation du
condensat.
The Mascot ST is standard as a Natural Gas Water
Heater and must be converted if propane is the desired
gas, unless specically manufactured for propane.
Adequate drainage
• The appliance should be installed not to damage
the adjacent area. If such locations cannot be
avoided, it is recommended that a suitable drain
pan, adequately drained, be installed under the
appliance. The pan must not block combustion air
ow.
Connecting the Water Supply
• To conserve water and energy, insulate all water
piping—especially the hot and recirculation water
lines. Never cover the drain or pressure relief valve.
Having a backow preventer in the cold water
supply line means that it prevent from thermal
expansion backow. Contact the water supplier or
local plumbing inspector for information about how
to control this situation. If overheating occurs or
the gas supply fails to shut o󰀨, turn o󰀨 the manual
gas valve.
This installation must conform with below section
• “Air for Combustion and Ventilation” of the
National Fuel Gas Code, ANSI Z224.1/NFPA 54,
or Sections 8.2, 8.3 or 8.4 of Natural Gas and
Propane Installation Code, CAN/CSA B149.1, or
applicable provisions of the local building codes.
CAUTION

LAARS Heating Systems
Page 16
Table 3. Required Exhaust Vent Material.
VENTING INSTALLATION STANDARDS
MATERIAL UNITED STATES CANADA
Stainless Steel UL 1738 Venting must be ULC-S636 certied for use as
PVC, sch 40 ANSI/ASTM D1785 venting material. The venting material must be chosen
CPVC, sch 40 ANSI/ASTM F441 based upon the intended application of the water heater.
Polypropylene UL1738 or ULC-S636
The ue temperature of the Mascot ST changes
dramatically with changes in operating water
temperature. Therefore, it is necessary to
assess the application of the water heater to
determine the required certied vent class. If the
Mascot ST is installed in an application where
the ambient temperature is elevated, and/or
installed in a closet/alcove, CPVC, polypropylene,
or stainless steel material is required. If the
system temperatures are unknown at the time of
installation, stainless, polypropylene or CPVC
material is recommended.
The Mascot ST is a Category IV appliance and may
be installed with PVC, CPVC or polypropylene that
complies with ULC-S636, ANSI/ASTM D1785 F441
(see Table 3) or a stainless steel venting system that
complies with UL 1738 Standard.
INSTALLATIONS IN CANADA require the use
of venting material certied to ULCS636. All
Gas vents connected to the Mascot ST, plastic,
stainless steel or otherwise must be certied to
this ULC standard. Appropriate selection of vent
material is very important for proper performance
and safe operation of the Mascot ST.
The ue temperature of the Mascot ST changes
dramatically with changes in operating water
temperature. Therefore, it is necessary to assess
the application of the water heater to determine
the required certied vent class. If the Mascot ST
is installed in an application where the outlet water
temperature exceeds 145°F, and/or installed in a
closet, class IIB or higher vent material is required.
If the system temperatures are unknown at the
time of installation, class IIB or higher venting
material is recommended.
IN CANADA all venting used must meet the
following requirements:
1. ULC-S636 certied and marked
2. The rst 3 feet of venting must be accessible
for visual inspection.
3. All components used in the vent system must
be from a certied manufacturer.
NOTICE
DO NOT COMMON VENT MASCOT ST UNITS.
Mascot ST units are never permitted to share a
vent with Category I appliances.
AVIS
NE PAS ÉVENT COMMUNE MASCOTTE ST
UNITÉS. Mascotte ST unités ne sont jamais
autorisés à partager un évent Catégorie I avec les
appareils.
WARNING
Use of cellular core PVC (ASTM F891), cellular core
CPVC, or Radel® (polyphenolsulfone) in venting systems
shall be prohibited.
WARNING
Failure to use the appropriate vent material, installation
techniques, glues/sealants could lead to vent failure
causing property damage, personal injury or death.
WARNING
All venting must be installed according to this manual and
any other applicable local codes, including but not limited
to, ANSI Z224.1/NFPA 54, CSA B149.1, CSAB149.2 and
ULC-S636. Failure to follow this manual and applicable
codes may lead to property damage, severe injury, or death.
NOTE: For Cascading Installations, please refer
to document 1351 ‘Cascading the Mascot ST’,
available online.
4.4 Venting (Exhaust)

Mascot ST Tankless Water Heater Page 17
4.5 General Location Guideline
1. Vent system installation must be in accordance
with Local codes or, in the absence of local codes,
the National Fuel Gas Code, ANSI Z224.1 /NFPA
54 and/or CSA B149.1, Natural Gas and Propane
Installation Code.
2. The Water Heater is designed to be installed as a
Direct Vent (sealed combustion) type.
The air for combustion must be supplied directly
from the outside to the burner. Also, the ue gases
must be vented directly to the outdoors (through
wall or roof).
3. Do not install venting system components on the
exterior of building except as specically required by
these instructions
- Vent terminals must be at least 1 foot from any door,
window, or gravity inlet into the building.
- Maintain the correct clearance and orientation
between the vent and air intake terminals.
The vent and air intake terminals must be at the
same height and their center lines must be spaced
apart 12˝ minimum.
- The bottom of the vent and air intake terminal must
be at least 12˝ above the normal snow line. In no
WARNING
Failure to vent this Water Heater in accordance
with these instructions could cause a re,
resulting in severe property damage, personal
injury or death.
Do not interchange vent systems or materials
unless it is specied.
The use of thermal insulation covering pipe and
ttings is prohibited.
Do not apply an electric damper, draft hood or
vent damper with this Water Heater.
Do not locate vent termination where exposed
to prevailing winds. Moisture and ice may fall
on surface around vent termination. To prevent
deterioration, surface must be in good repair
(sealed, painted, etc.).
case should they be less than 12˝ above grade
level.
- Do not install the vent terminal directly over
windows or doors.
- Air intake terminal must not terminate in areas that
might contain combustion air contaminates, such as
near swimming pools.
- For sidewall venting, the minimum horizontal
distance between any adjacent individual Module
(Water Heater) vent terminations is twelve (12)
inches. It is better to be far more than 12 inches for
avoiding frost damage to building surfaces where
vent terminations are placed.
- The minimum horizontal distance between any
adjacent individual module (water heater) roof vent
endpiece is one (1) foot.
4 . Vent system components must not be mixed
with alternate manufacturers certied
components and/or unlisted components.
5 . The venting must be installed according
to the vent manufacturers installation
instructions.
The unit’s vent can terminate through the roof, or
through an outside wall.
Vent pipe must pitch upward, toward the vent
terminal, not less than 1/4” per foot, so that
condensate will run back to the Mascot ST to drain.
Route vent pipe to the heater as directly as possible.
Seal all joints and provide adequate hangers as
required in the venting system manufacturer’s
Installation Instructions. Horizontal portions of
the venting system must be supported to prevent
sagging and may not have any low sections that
could trap condensate. The unit must not support the
weight of the vent pipe.

LAARS Heating Systems
Page 18
4.6.1 Direct Venting Clearances
U.S. Installations (see note 1) Canadian Installations (see note 2)
A= Clearance above grade, veranda, porch, 12 inches (30 cm) 12 inches (30 cm)
deck, or balcony See note 6 See note 6
B= Clearance to window or door that may be Direct vent only: 12 inches (30cm); 36 inches (91 cm)
opened Other than Direct vent: 4 ft (1.2m) below or to NT 80 only - 12 inches (30 cm)
side of opening; 1 ft (30cm) above opening
C= Clearance to permanently closed window See note 4 See note 5
D= Vertical clearance to ventilated so󰀩t located
above the terminal within a horizontal See note 4 See note 5
distance of 2 feet (61cm) from the center
line of the terminal
E= Clearance to unventilated so󰀩t See note 4 See note 5
F= Clearance to outside corner See note 4 See note 5
G= Clearance to inside corner See note 4 See note 5
H= Clearance to each side of center line 3 feet (91 cm) within a height 15 feet
extended above meter/regulator assembly See note 4 above the meter/regulator assembly
I= Clearance to service regulator vent outlet See note 4 3 feet (91 cm)
J= Clearance to nonmechanical air supply Direct vent only: 12” (30cm) 80-285; 36” (91cm)
inlet to building or the combustion air inlet 399-850. Other than Direct vent: 4 ft (1.2m) below 36 inches (91 cm)
to any other appliance or to side of opening; 1 ft (30cm) above opening NT 80 only - 12 inches (30 cm)
K= Clearance to a mechanical air supply inlet 3 feet (91 cm) above if within 10 feet (3 m) 6 feet (1.83 m)
horizontally
L= Clearance above paved sidewalk or paved Vent termination not allowed in this location 7 ft (2.1 m)
driveway located on public property for category IV appliances. See note 5
M= Clearance under veranda, porch, deck, See note 4 12 inches (30 cm) (see note 3)
or balcony
Notes:
1. In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Gas Code.
2. In accordance with the current CAN/CSA-B149.1 Installation Codes.
3. Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the oor.
4. For clearances not specied in ANSI Z223.1 / NFPA 54, clearance is in accordance with local installation codes and the requirements of the gas supplier.
5. For clearances not specied in CAN/CSA-B149, clearance is in accordance with local installation codes and the requirements of the gas supplier.
6. IMPORTANT: Terminal must be placed such that it remains a minimum 12” above expected snow line. Local codes may have more
specic requirements, and must be consulted.
4.6 Locations for Vent Pipe Terminator
Table 4. Direct Vent Clearances

Mascot ST Tankless Water Heater Page 19
Description US Non-Direct Canadian Non-Direct
AClearance above grade, veranda, porch, deck, or balcony 12 in (30 cm) 12 in (30 cm)
BClearance to window or door that may be opening
48 in (120 cm) below
or to side of opening;
12 in (30 cm) above
opening
36 in (91 cm)
CClearance to permanently closed window * *
D
Vertical clearance to ventilated so󰀩t located above the terminal
within a horizontal distance of 2 feet from the center line of the
terminal * *
EClearance to unventilated so󰀩t * *
FClearance to outside corner * *
GClearance to inside corner * *
HClearance to each side of center line extended above
meter / regulator assembly *
36 in (91 cm) within a
height 15 ft (4.57 m)
above the meter/ regu-
lator assembly
IClearance to service regulator vent outlet * 36 in (91 cm)
JClearance to non-mechanical air supply inlet to building or the
combustion air inlet to any other appliance
48 in (120 cm) below
or to side of opening;
12 in (30 cm) above
opening
36 in (91 cm)
KClearance to a mechanical air supply inlet 36 in (91 cm) above
if within 10 ft (3 m)
horizontally
6 ft (1.83 m)
LClearance above paved sidewalk or paved driveway located on
public property *7 ft (2.13 m)
MClearance under veranda, porch, deck, or balcony * 12 in (30 cm)
4.6.2 Non-Direct Venting (Single Pipe) Clearances
Table 5. Non-Direct Vent Clearances

LAARS Heating Systems
Page 20
4.6.3 Venting Requirements in the
Commonwealth of Massachusetts
In Massachusetts the following items are required if
the side-wall exhaust vent termination is less than
seven (7) feet above nished grade in the area
of the venting, including but not limited to decks
and porches. From Massachusetts Rules and
regulations 248 CMR 5.08
1. Installation of Carbon Monoxide Detectors
At the time of installation of the side wall
vented gas fueled appliance, the installing plumber
or gastter shall observe that a hard-wired carbon
monoxide detector with an alarm battery back-up is
installed on the oor level where the gas appliance
is to be installed. In addition, the installing plumber
or gastter shall observe that a battery operated or
hard-wired carbon monoxide detector with an alarm
is installed on each additional level of the dwelling,
building or structure served by the side-wall
horizontally vented gas fueled equipment. It shall
be the responsibility of the property owner to secure
the services of qualied licensed professionals
for installation of hard-wired carbon monoxide
detectors.
a. In the event that the side-wall horizontally
vented gas fueled equipment is installed in a crawl
space or an attic, the hard-wired carbon monoxide
with alarm and battery back-up may be installed on
the next adjacent oor level.
b. In the event that the requirements of the
subdivision cannot be met at the time of completion
of installation, the owner shall have a period of thirty
(30) days to comply with the above requirements,
provided, however, that during said thirty (30)
day period, a battery operated carbon monoxide
detector with an alarm be installed.
2. Approved Carbon Monoxide Detectors
Each carbon monoxide detector shall comply
with NFPA 720 and be ANSI/UL 2034 listed and IAS
certied.
3. Signage. A metal or plastic identication plate
shall be permanently mounted to the exterior of
the building at a minimum height of eight (8) feet
above grade directly in line with the exhaust vent
terminal for horizontally vented gas fueled heating
appliance or equipment. The sign shall read, in
print no less than one-half (1/2) inch in size: “GAS
VENT DIRECTLY BELOW, KEEP CLEAR OF ALL
OBSTRUCTIONS”.
4. Inspection The state or local gas inspector of
the side-wall horizontally vented gas fueled appliance
shall not approve the installation unless, upon
inspection, the inspector observes carbon monoxide
detectors and signage installed in accordance with the
provisions of 248 CMR 5.08(2)(a) 1-4.