MASCOT MSTWW User manual

Installation and Operation Instructions Document 1316
H2372600-
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) - Field-Convertible

LAARS Heating Systems
TABLE OF CONTENTS
SECTION 1
Product Accessories
1.1 Introduction .......................................................... 1
1.1 Included with the Appliance ................................... 1
SECTION 2
Product Characteristics
2.1 Model Nomenclature ................................................2
2.2 Specications ...........................................................3
2.3 Dimensions ..............................................................4
2.4 Names of Components ............................................5
SECTION 3
Safety Regulations
3.1 Safety Symbols ..................................................... 6
3.2 Safety Precautions and Proper Use ...................... 8
SECTION 4
Installation
4.1 Location and Clearances .......................................10
4.2 Wall Mount Bracket ................................................. 11
4.2.1 Installation Height and Location ................. 11
4.2.2 Hang the Water Heater .............................. 11
4.3 Combustion Air .......................................................12
4.3.1 Combustion Air from Room ..........................12
4.3.2 Ducted Combustion Air ................................12
4.4 Venting (exhaust) ...................................................14
4.5 General Location Guideline ................................... 15
4.6 Locations for Vent Pipe Terminator ........................ 15
4.6.1 Direct Venting Clearances ........................... 16
4.6.2 Non-Direct Venting Clearances .....................17
4.6.3 Venting Requirements in Massachusetts ......18
4.7 Air / Vent Connections at the Appliance .................20
4.7.1 Vent / Air Pipe Lengths .................................20
4.7.2 Direct Venting ...............................................20
4.7.3 Indoor Combustion Air .................................21
4.8 Vent / Air Pipe Termination ..................................... 21
4.9 Gas Supply and Piping .......................................... 23
4.10 Gas Supply Pressure ............................................26
4.11 Gas Set Up and Adjustment .................................. 26
4.12 Gas High Altitude Setting ......................................27
4.13 Natural Gas to Propane Conversion .....................28
4.14 Plumbing Guideline ...............................................32
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 Control Board, Electrical Diagram ........................ 36
4.20 Ladder Diagram ....................................................37
4.21 Electrical Connections .......................................... 38
SECTION 5
Control Display and Operation
5.1 Control Dial and Buttons ....................................... 40
5.2 LCD Overview ....................................................... 41
5.3 Operating Mode .................................................... 42
5.5 Status Display Mode ........................................... 43
5.4 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
SECTION 7
Trouble Shooting
7.1 Diagnostics .......................................................... 52
7.1 Failure Modes ..................................................... 53
SECTION 8
Maintenance
8.1 Annual Startup and General Maintenance .......... 56
SECTION 9
Installation Check
9.1 Quick View .......................................................... 57
9.2 Final Check Lists ................................................. 57
SECTION 10
Repair Part Diagram
10.1 Part List ............................................................... 62
10.2 Notes: ................................................................. 66

Mascot ST Tankless Water Heater Page 1
SECTION 1. Product Accessories
Items Descriptions Qty
LAARS Tankless Water Heater 1
Installation Instructions and
Users Manual 1
Condensate Hose 1
Wall Mount Bracket 1
Bolts w/Anchors 4
Vent terminal cap 3” 2
Parts Kit 1
Installationand Operation Instructions Document1316
H2372600-
WARNING
Ifthe information in this manual is not
followed exactly, a  re or explosion may
result causing property damage, personal
injuryor loss of life.
Donot store or use gasoline or other
 ammable vapors and liquids in the vicinity of
this or any other appliance.
WHATTO 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.
FORYOUR 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.
QUEFAIRE 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
dufournisseur.
• 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
M ASCOT
®
ST
Wall-Mounted, Modulating
Gas Condensing Water Heater
Model MSTWW
199,000 BTU/hr
• NaturalGas(NG)-FactoryConguration
• Propane Gas (LP) - Field-Convertible
User’s Manual - Mascot ST Water Heater
Page1
User’s Manual Document1317
H2372700-
WARNING
Ifthe information in this manual is not
followed exactly, a  re or explosion may
result causing property damage, personal
injuryor loss of life.
Donot store or use gasoline or other
 ammable vapors and liquids in the vicinity
of this or any other appliance.
WHATTO 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.
FORYOUR 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 ni
d’autres vapeurs ou liquides in ammables dans
le voisinage de cet appareil ou de tout autre
appareil.
QUEFAIRE 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 dansle bâtiment où vous êtes.
• Appelez immédiatement votre fournisseur de
gaz depuis un voisin. Suivez les instructions
dufournisseur.
• 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.
User’s Manual
M ASCOT
®
ST
Wall-Mounted, Modulating
Gas Condensing Water Heater
Model MSTWW
199,000 BTU/hr
• NaturalGas(NG)-FactoryConguration
• Propane Gas (LP) - Field-Convertible
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 Appliance

LAARS Heating Systems
Page 2
Figure 1. Model Nomenclature
2 3 4 5 6 7 8 9 10 11 12 13
S T W W 1 9 9 A 1 X 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
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.

Mascot ST Tankless Water Heater Page 3
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″
Weight 88lbs
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 Off 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 4
Description Diameter
A
Vent Pipe Collar
3"
B
Air Intake Collar
3"
C Gas Inlet 3/4"
D DHW Outlet 3/4"
EDHW Inlet 3/4"
F Condensate Drain 1/2"
G Cold Water Inlet Filter _
2.3Dimensions
Air Intake
Vent

Mascot ST Tankless Water Heater Page5
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 6
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.
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 7
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-off valve
andoperationmethod.Closethegasshut-offvalve
immediatelyiftheapplianceissubjectedtore,
overheating,ood,physicaldamage,oranyother
damaging condition that might affect 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
shutoffsystem.
If the error code ‘41’ occurs, follow the instructions
below.
-First,turnoff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 off 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8
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insufcient
water or no water is
intheheatingpipes.
(valve: always open
position)
4.ChecktheGasValve
Check that the manual gas shut-off 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suf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.
SECTION 3.
Safety Regulations
3.2SafetyPrecautionsandProperUse