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Installation and Operation Instructions
FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,
qualified in hot water boiler and heater installation and maintenance. Improper installation and/or operation
could create carbon monoxide gas in flue gases which could cause serious injury, property damage, or
death. Improper installation and/or operation will void the warranty.
WARNING
If the information in this manual is not
followed exactly, a fire or explosion may
result causing property damage, personal
injury or loss of life.
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
nearby 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 gas
supplier.
Installation and Operation
Instructions for
M
ASCOT
Wall-Mounted, Modulating
Gas Condensing Water Heater
Model MSTWW
199,000 BTU/hr
Natural Gas (NG) - Factory Configuration
•
Propane Gas (LP) - Factory Configuration
•
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 inflammables dans
le à proximité de cet appareil ou de tout autre
appareil.
QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE
• 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 qualifié
ou par le fournisseur de gaz.
Document 1316E
ST
®
AVERTISSEMENT
GAZ:
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Related Manuals for Laars MSTWW199
Summary of Contents for Laars MSTWW199
- Page 1 Installation and Operation Instructions Document 1316E Installation and Operation Instructions for ASCOT ® Wall-Mounted, Modulating Gas Condensing Water Heater Model MSTWW 199,000 BTU/hr Natural Gas (NG) - Factory Configuration • Propane Gas (LP) - Factory Configuration • FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician, qualified in hot water boiler and heater installation and maintenance.
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Page 2: Table Of Contents
LAARS Heating Systems TABLE OF CONTENTS SECTION 1 Product Accessories Introduction ............3 4.12 Gas High Altitude Setting ........30 Included with the Unit ...........3 4.13 Gas Conversion ..........30 4.14 Plumbing Guidelines........31 4.15 Disposal of Condensate ........33 SECTION 2 Product Characteristics Model Nomenclature ..........4... -
Page 3: Section 1 Product Accessories
Consult the LAARS Heating All electrical wiring is to be done in accordance with the local Systems factory, or your local factory representative, with any codes, or in the absence of local codes, with: 1) The National problems or questions regarding this equipment. -
Page 4: Model Nomenclature
LAARS Heating Systems Page 4 SECTION 2 Product Characteristics Model Nomenclature The Model Nomenclature is shown on your Rating Plate and consists of a series of letters and numbers ( Nomenclature ) that further identifies the characteristics of your Mascot ST. -
Page 5: Specifications
Mascot ST Tankless Water Heater Page 5 Specifications Model Name MSTWW199 199,000 Btu/h Gas Input Rate 19,900 Btu/h 35°F Rise 11.0 GPM 45°F Rise 8.5 GPM Hot Water Capacity 77°F Rise 5.0 GPM Installation Indoor Wall Hung Sealed Combustion Direct & Single Vnet... -
Page 6: Dimensions
LAARS Heating Systems Page 6 Dimensions Vent Air Intake Description Diameter Vent Pipe Collar 3" Air Intake Collar 3" Gas Inlet 3/4" DHW Outlet 3/4" DHW Inlet 3/4" Condensate Drain 1/2" Cold Water Inlet Filter... -
Page 7: Names Of Components
Mascot ST Tankless Water Heater Page 7 Vent Names of Components Combustion Name of Component Name of Component Vent Pipe Collar Cold Water Inlet Combustion Air Intake Assembly Cold Water Inlet Filter Air Gas Mixture (AGM) Actuator Manual Power Switch Ignition Transformer DHW Temperature Sensor Igniter... -
Page 8: Section 3 Safety Regulations Safety Symbols
Water Heater. or explosion could result causing property dam- age, personal injury or loss of life. Laars cannot anticipate every circumstance A. This appliance does not have a pilot. It that might involve a potential hazard. Therefore,... -
Page 9: Safety Precautions And Proper Use
(dripping, spraying, rain, etc.) during operation and service (circulator replacement, condensate trap, control replacement, etc.). The Laars Water Heater must be installed by a qualified plumber, a licensed gas fitter, and/or a professional service technician. - Page 10 LAARS Heating Systems Page 10 Safety Precautions and Proper Use When in Operation Before Operation CAUTION 1. Caution for Gas leak 1. Check the Gas Type (NG/LP) Frequently check for a gas leak at the gas connection When using or moving the unit for the first time, check portion with soapy water.
- Page 11 Mascot ST Tankless Water Heater Page 11 WARNING Do not use the appliance for any other purpose than for heating and hot water. Do not store combustibles or flammable material such as gasoline near the appliance. Do not store other items on or near this water heater. Do not store combustible (flammable) materials such as papers.
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Page 12: Section 4 Installation
LAARS Heating Systems Page 12 SECTION 4 Installation WARNING Location and Clearances Installations must comply with The Mascot ST must be mounted to a suitable wall by • All the local, state, provincial, and national codes, a qualified heating contractor under the guidelines of a laws, regulations and ordinances. -
Page 13: Wall Mount Bracket
Mascot ST Tankless Water Heater Page 13 Wall Mount Bracket 3" to Top of Unit 4.2.1 The installation height and location Anchors 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 Concrete, best position to mount the Wall Mount Bracket. -
Page 14: Combustion Air
When taken from the wall, it must Two permanent openings, one commencing Method 1: be taken from out-of-doors by means of the LAARS within 12” (300mm) of the top and one commencing horizontal wall terminal. When taken from the roof, a within 12”... - Page 15 Mascot ST Tankless Water Heater Page 15 NOTICE AVIS The instructions for the installation of the venting Les instructions d'installation du système system shall specify that the horizontal portions of d'évacuation doivent préciser que les sections the venting system shall be supported to prevent horizontales doivent être supportées pour prévenir sagging;...
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Page 16: Venting (Exhaust)
LAARS Heating Systems Page 16 Venting (Exhaust) NOTE: For Cascading Installations, please refer The flue temperature of the Mascot ST changes to document 1351 ‘Cascading the Mascot ST’, dramatically with changes in operating water available online. temperature. Therefore, it is necessary to assess the application of the water heater to determine the required certified vent class. -
Page 17: General Location Guideline
Mascot ST Tankless Water Heater Page 17 WARNING 4 . Vent system components must not be mixed Failure to vent this Water Heater in accordance with alternate manufacturers certified with these instructions could cause a fire, components and/or unlisted components. resulting in severe property damage, personal 5 . -
Page 18: Locations For Vent Pipe Terminator
LAARS Heating Systems Page 18 Locations for Vent Pipe Terminator 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... -
Page 19: Non-Direct Venting Clearances
Mascot ST Tankless Water Heater Page 19 Non-Direct Venting (Single Pipe) Clearances 4.6.2 Description US Non-Direct Canadian Non-Direct Clearance above grade, veranda, porch, deck, or balcony 12 in (30 cm) 12 in (30 cm) 48 in (120 cm) below or to side of opening; Clearance to window or door that may be opening 36 in (91 cm) 12 in (30 cm) above... -
Page 20: Venting Requirements In The Commonwealth Of Massachusetts
LAARS Heating Systems Page 20 Venting Requirements in the 4.6.3 Commonwealth of Massachusetts In Massachusetts the following items are required if the side-wall exhaust vent termination is less than shall be permanently mounted to the exterior of seven (7) feet above finished grade in the area... -
Page 21: Common Vent Test
Mascot ST Tankless Water Heater Page 21 NOTICE AVIS NE PAS ÉVENT COMMUNE MASCOTTE ST UNITÉS. DO NOT COMMON VENT MASCOT ST UNITS. Mascot ST units are never permitted to share a Mascotte ST unités ne sont jamais autorisés à partager un évent Catégorie I avec les appareils. -
Page 22: Air Supply And Vent Connections
The following steps for cement application are highlighted: Clean and dry your selected PVC, CPVC vent pipe and Laars Water Heater collar (socket). - You can select to the size of vent pipe(2˝ & 3˝), according to the installation conditions. -
Page 23: Single Venting
1. Insert the termination end cap into the intake air duct. 2. Provide two openings to allow for circulation of combustion air as specified by ANSI Z224.1/NFPA 54 or CAN/CGA B-149.1: Model MSTWW199 Maximum Input 199,000 (BTU/H) Indoor make up air is 199 in 2 14 1/4"... - Page 24 LAARS Heating Systems Page 24 4.9 Vent Pipe Termination (cont) Horizontal Vent Termination • Direct Vent - Sidewall Termination Exterior Wall Vent Screens are required 1” MIN Exhaust Elbow 12” MIN 12” MIN Exhaust Apart Exhaust Screen NOTE: The Exhaust must Air Intake Screen NOTE: Must be 12”...
- Page 25 Mascot ST Tankless Water Heater Page 25 • Direct Vent - Optional Side wall Terminations Exterior Wall Concentric Vent Termination • Direct Vent - Optional Horizontal Exterior Wall and Vertical Concentric Vent Side Wall Kit (2” or 3”) Side Wall Kit Exhaust (2”...
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Page 26: Gas Supply And Piping
LAARS Heating Systems Page 26 Gas Supply and Piping WARNING: Gas piping should be supported by suitable hangers or Open flame can cause gas to ignite and result in floor stands, not the appliance. property damage, severe injury, or loss of life. - Page 27 Mascot ST Tankless Water Heater Page 27 4.9 Gas Supply and Piping (continued) The gas connection fitting on the unit is 3/4˝ male To facilitate any future maintenance, it is also NPT. recommended that an approved gas union fitting be installed in the supply line between the shut-off valve The supply line must be sized for the maximum and the 3/4˝...
- Page 28 LAARS Heating Systems Page 28 Natural Gas piping installation. The Water Heater is recommended to be the first appliance to be connected to the gas supply line. Union Other appliance Connection Manual gas shut off valve 1/2"~3/4" Gas pipe size...
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Page 29: Gas Supply Pressure
CO should not exceed 300 ppm. conversion during warm weather. 2" or 3" VENT 2" or 3" VENT MSTWW199 2. Set up your combustion analyzer and place the Standard Factory Setting is for MIN Fire. 9.0% Write in the correct Conversion Date and the sensor in the combustion test port. -
Page 30: Gas High Altitude Setting
LAARS Heating Systems Page 30 5. Change dip switch 6 to OFF and 7 to ON. The unit 9. It may be necessary to go back and forth will cycle down to MIN fire. between MAX fire and MIN fire several times 6. -
Page 31: Plumbing Guidelines
Mascot ST Tankless Water Heater Page 31 4.14 Plumbing Guidelines. - Ensure pipe material is suitable for the local codes and industry standards. - The pipe must be cleaned and without any debris. - Do not apply torch heat within 12˝ of the bottom connections of the unit. - The pipe size used for supply heating water should be the same size used for the return heating water. - Page 32 LAARS Heating Systems Page 32 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. __________________________________________...
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Page 33: Disposal Of Condensate
Damage caused by failure to install a neutralizer kit or to adequately treat condensate will not be the manufacturer’s responsibility. * Contact Laars to order Kit# A2123601 _________________________________________... -
Page 34: Pressure Relief Valve
LAARS Heating Systems Page 34 4.16 Pressure Relief Valve WARNING An approved ‘Pressure Relief Valve’ must be included in this installation. The Valve must be an approved ASME HV Relief Valve, installed on the DHW supply line for domestic hot water loop as close to the unit as possible. -
Page 35: Dip Switches
Mascot ST Tankless Water Heater Page 35 4.18 DIP Switches There is one set of DIP switches. DIP switches 6 and 7 must be set to OFF when operating the water heater normally. DIP Switch Function Machine power Do NOT Move. OVER-RIDE Inlet DHW Flow Limiter Propane or Natural Gas Max. -
Page 36: Wiring Diagram
LAARS Heating Systems Page 36 4.19 Wiring Diagram... -
Page 37: Ladder Diagram
Mascot ST Tankless Water Heater Page 37 4.20 Ladder Diagram... -
Page 38: Electrical Connections
LAARS Heating Systems Page 38 4.21 Electrical Connections Connector Descriptions HT SELV #, Location, Type Label CASE GROUND Power Supply Line HT (120VAC) HT (120VAC) Not Used Igniter HT (120VAC) HT (120VAC) L(HT) Heater 65001WS-12 Gas Valve HT (120VAC) EARTH GROUND... - Page 39 Mascot ST Tankless Water Heater Page 39 4.22 Electrical Connections (continued) Connector Description HT SELV #, Location, Type Label Flame Detect Sensor SELV (5VDC) OP.S Operation water temperature sensor SELV (5VDC) DH.S DHW temperature sensor SELV (5VDC) Inlet water temperature sensor SELV (5VDC) LWD1140-14 BG.S...
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Page 40: Section 5 Control Display And Operation
LAARS Heating Systems Page 40 Control Display and Operation SECTION 5 Control Dial and Buttons Status Light (constant green when operating normally) The Control Display has a Control Dial (E), 4 buttons (A, B, C, D), and a Liquid Crystal Display (with 72 back-lit segments). This section of this manual gives instruction on how to navigate into the many functions of the Mascot ST and to change temperature set points, set system variables and controller parameters. -
Page 41: Lcd Overview
Mascot ST Tankless Water Heater Page 41 LCD Overview Lock Communicating Status and Installer Modes Flame Signal Numeric Display Domestic Hot Water Mode Lock mode Buttons-locked mode icon Communication Communication icon Status and Installer mode The Status Mode or the Installer Mode is Active (all parameters) Flame signal Flame Signal icon Numeric Display... -
Page 42: Operating Mode
LAARS Heating Systems Page 42 Operating Mode Operating Mode After the Power is turned on, and/or the Control Display is turned on , the Control Display will go through a ‘Start Up’ checklist and briefly show a sequence of diagnostic codes before entering into the ‘Operating Mode. -
Page 43: Status Display Mode
Mascot ST Tankless Water Heater Page 43 AUTODESK � � � � � � � � � � Status Display Mode Index Description Parameter Flow 1 Current flow value(Li: L/m, GA: GPM) A: Li or A: GA b: Fr Fan rpm Current fan rpm value Lock Mode Lock mode is used(On) or unused(oFF) -
Page 44: Dhw Set Point Change Mode
LAARS Heating Systems Page 44 DHW Set Point Change Mode The Mascot ST has a built in INLET DHW Flow Limiter and will automatically adjust the DHW flow rate up or down based on DHW outlet temperature at the inlet side of the water heater. -
Page 45: Installer Mode
Mascot ST Tankless Water Heater Page 45 Installer Mode AUTODESK � � � � � � � � � � These changes are to be made only by a qualified technician. To c hange any of the Installer Parameters, Start by turning OFF the Power to the Display Control. -
Page 46: Error Mode
LAARS Heating Systems Page 46 Error Mode Flashing Indicate Example Error ‘ Er : ’ will flash Er:11 Er:11 Error Code Display and Controller are communicating NOTE: When communication between the Control Display and the main controller is lost, the... -
Page 47: Section 6 Error Codes
Mascot ST Tankless Water Heater Page 47 SECTION 6 Error Codes Error Codes Error Recover Error Code Description Possible Remedies Code methods Press the Power button to clear the Error Code. If Error happens again: 1. Monitor the gas pressure to the water heater while in operation. Ensure pressure is between 3.5 and 14” WC. 2. - Page 48 LAARS Heating Systems Page 48 Error Recover Error Code Description Possible Remedies Code methods This Error Code will go away when outlet water temperature decreases. Operating If Error happens again: Temperature Sensor 1. Check operating temperature sensor. Ensure connections are secure.
- Page 49 Mascot ST Tankless Water Heater Page 49 6.1 Error Codes (continued) Error Recover Error Code Description Possible Remedies Code methods Press the Power button to clear the Error Code. If Error happens again: Supply Water Valve 1. Turn power OFF and ON at the main power switch internal to the water heater. Hard Lock Error 2.
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Page 50: Fault Tree Analysis
LAARS Heating Systems Page 50 Fault Tree Analysis 6.2.1 Flame Detection 6.2.2 Gas Detection... -
Page 51: I/T', 'Dhw', 'Op' Sensor Detects
Mascot ST Tankless Water Heater Page 51 6.2 Fault Tree Analysis (continued) Fan / Air Proving 6.2.3 ‘I/T’, ‘DHW’, ‘OP’ Sensor detects 6.2.4 Error code contents Inlet water NTC open or short DHW NTC open or short OP NTC open or short Exhaust NTC open or short... -
Page 52: Section 7 Troubleshooting
LAARS Heating Systems Page 52 SECTION 7 Troubleshooting Diagnostics Before calling for service, review the following diagnostic steps first for saving time and money. Question & Answer Indicate Indicator Make sure that the ON/OFF button on the Control Panel has been turned ON. - Page 53 Mascot ST Tankless Water Heater Page 53 7.1 Diagnostics (continued) Diagnostics and suggested corrective actions This controller is able to record information about the water heater’s condition for the ten previous faults or errors. Refer to the ‘Error Code’ section of this Manual, (Section 6). Display Condition Diagnostic...
- Page 54 LAARS Heating Systems Page 54 Display Condition Diagnostic Corrective Action(s) Burner may be operating too hot due to incorrect combustion. Occurs when flame Reset using manual switch. Reset screen on control Check for flame at burner via flame current with...
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Page 55: Section 8 Maintenance
Mascot ST Tankless Water Heater Page 55 Annual Startup and General Maintenance SECTION 8 Maintenance Maintenance procedures [ Periodically ] Regular Maintenance After Water Heater installation is completed, this - Check power source. manual should be placed in safe dry location near the water heater. - Page 56 LAARS Heating Systems Page 56 - Cleaning Air Intake Filter - To properly maintain the water heater, you should clean the air intake filter every 3 months. If not, you may encounter combustion issues To clean air intake filter: 1. Press Power button on the control panel to turn off the water heater.
- Page 57 Mascot ST Tankless Water Heater Page 57 8.1 Annual Startup and General Maintenance (continued) 8. Disconnect all hoses. - Flushing the Water Heater 9. Remove the cold water inlet filter from the water heater Flushing the Heat Exchanger of water heater is a and clean out any residues.
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Page 58: Section 9 Installation Check 9.1 Quick View
LAARS Heating Systems Page 58 SECTION 9 Installation Check Quick View Final check lists Before Installing Final check : Installation Conditions. - Make sure that there is enough space for installing • Is the Water Heater properly mounted on the wall? Water and gas line. - Page 59 Mascot ST Tankless Water Heater Page 59 Final Check List (continued) Final check : Connecting the power supply • Please check that the power is 120V AC. • Have you checked the polarity of the electrical connection? Final check : Pressure relief valve •...
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Page 60: Section 10 Repair Part List And Diagrams
LAARS Heating Systems Page 60 SECTION 10 Repair Part List and Diagrams 10.1 Parts List antaneous Water Heater Part Number - Model begins with "ST" rarmi # IOM Ref Laars # Description antaneous Water Heater Part Number - Model begins with "ST"... - Page 61 Mascot ST Tankless Water Heater Page 61 Cover Assembly...
- Page 62 LAARS Heating Systems Page 62 neous Water Heater Part Number - Model begins with "ST" mi # IOM Ref Laars # Description ST1001 Exhaust Vent Duct ASS'Y ST1002 Case ST1003 Front Cover ASS'Y 3‐1 ST1003 Front Cover 3‐2 ST1004 Black Bezel 3‐3 ST1005 Control display cover/window ST1006 Ignition Transformer ST1007 Gas Inlet Nipple...
- Page 63 11400020 ST1008 Overheat Sensor 160420004 ST1009 DHW Supply Pipe ASS'Y Mascot ST Tankless Water Heater Page 63 49100124 7‐1 ST1010 DHW Supply Pipe 11300015 7‐2 ST1011 Water Outlet Sensor 160522003 ST1012 Siphon ASS'Y ST1013 Siphon Air Pressure Hose 64100022 ST1014 Air Pressure Switch 64100022 ST1015 Bracket for control display 140350003 ST1016 Control Display (920C) 14110021 ST1017 Printed Circuit Board 140210024 ST1018 PCB Bracket 140210024 ST1019...
- Page 64 Customer Service and Product Support: Industrial Way, Rochester, NH, USA 03867 • 603.335.6300 • Fax 603.335.3355 Headquarters: 9 Brigden Gate, Halton Hills, Ontario, Canada L7G 0A3 (905) 203-0600 Fax: (905) 636-0666 www.Laars.com Litho in U.S.A. © Laars Heating Systems 20-01 Document 1316E...