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Installation and Operation Instructions 

Document 1211J

H2329100J

Hydronic Boiler

Model MT2H

Volume Water Heater

Model MT2V

Sizes 500–2000 MBTU/h

 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.

 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 inflammables dans 

le voisinage 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 dansle bâtiment où vous êtes.

•  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.

FOR YOUR SAFETY:

 This product must be installed and serviced by a professional service technician, 

qualified in hot water boiler 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. For indoor installations, as an additional 

measure of safety, Laars strongly recommends installation of suitable Carbon Monoxide detectors in the 

vicinity of this appliance and in any adjacent occupied spaces.

Installation and Operation Instructions for

MIGHTY THERM

2

 ®

Summary of Contents for MIGHTY THERM2

Page 1: ...iser d essence ni d autres vapeurs ou liquides inflammables dans le voisinage 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...

Page 2: ...Heaters 4B 1 Water System Piping Water Heater 14 4B 2 Hot Water Supply Piping Water Heater 15 4B 3 Water Flow Requirements Water Heater 15 4B 4 Combined Water Heating potable and Space Heating Water H...

Page 3: ...or local factory representative with any issues or questions regarding this equipment Experience has shown that most operating issues are caused by improper installation The Mighty Therm2 appliance is...

Page 4: ...ate packages Verify receipt of all packages listed on the packing slip Inspect everything for damage immediately upon delivery and advise the carrier of any shortages or damage Any such claims should...

Page 5: ...d for 30 feet 9 1m of piping If the appliance must be installed with longer piping runs then larger diameter pipe or tubing shall be used Consult the factory for assistance Figure 1 Dimensional Data s...

Page 6: ...Dimensional Data pump mounted models HORIZONTAL INTAKE AIR VENT COLLAR VENT PIPE PIPE MAX PIPE MAX NO SIDE WALL SIDE WALL SIZE SIZE DIAMETER DIAMETER LENGTH OF ELBOWS VENT COMBUSTION TERMINAL AIR TER...

Page 7: ...all 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 v...

Page 8: ...the vent system must conform to the National Fuel Gas Code ANSI Z223 1 Latest Edition in the U S or in Canada to CSA B149 1 latest edition The vent system must be sized and installed for a Category I...

Page 9: ...ppliances with condensing vents are not permitted to terminate above a public walkway or over an area where condensate or vapor could create a nuisance or hazard 3 Locate the vent terminal so that ven...

Page 10: ...et 3 feet 91 cm above if within 10 feet 3 m 6 feet 1 83 m horizontally Vent termination not allowed in this location Vent termination not allowed in this location for category IV appliances A vent sha...

Page 11: ...irectly in line with the exhaust vent terminal for the horizontally vented gas fueled heating appliance or equipment The sign shall read in print size no less than one half inch in size GAS VENT DIREC...

Page 12: ...ing system Turn on any exhaust fans such as range hoods and bathroom exhausts so they will operate at maximum speed Do not operate a summer exhaust fan Close fireplace dampers 4 Place in operation the...

Page 13: ...e gas supply piping during any pressure testing of that system at test pressures in excess of 1 2 PSIG 3 45kpa 9 The unit must be isolated from the gas supply system by closing its individual manual s...

Page 14: ...r oxygen is introduced into the system To ensure a proper operating temperature leading to long boiler life a flow rate has been established based on the fluid temperature rise for this specific size...

Page 15: ...o be aggressive and can erode metals including copper if the water is moved too quickly The water flow requirements for the Mighty Therm2 water heater are based upon the hardness of the water The wate...

Page 16: ...LAARS Heating Systems Page 16 Figure 6 Hydronic Piping Multiple Boilers Primary Secondary System Figure 7 Hydronic Piping Multiple Boilers Low Temperature System...

Page 17: ...Mighty Therm2 Page 17 Figure 8 Hydronic Piping One Boiler Multi Temperature System Figure 9 Hydronic Piping Primary Secondary Reverse Return...

Page 18: ...LAARS Heating Systems Page 18 Figure 10 Hydronic Piping Primary Secondary Reverse Return Low Temperature Figure 11 Water Heater Piping One Heater One Tank...

Page 19: ...Mighty Therm2 Page 19 Figure 12 Water Heater Piping Multiple Heaters One Tank Figure 13 Water Heater Piping One Heater Multiple Tanks...

Page 20: ...19 170 257 341 0 6 1 1 1 9 21 14 10 1250 68 68 90 3 8 3 8 6 3 31 31 24 257 257 341 1 2 1 2 1 9 17 17 13 1500 68 68 90 3 9 3 9 6 5 38 38 28 257 257 341 1 2 1 2 2 0 21 21 16 1750 68 68 90 4 0 4 0 6 7 4...

Page 21: ...ipe or dielectric unions may isolate the boiler electrically Service and maintenance personnel who work on or around the boiler may be standing on wet floors and could be electrocuted by an ungrounded...

Page 22: ...2 BLOWER 1 LOW HIGH LOW HIGH K1 K2 K1 K2 F2 35 67 F2 35 67 F1 35 67 F1 35 67 K3 HSI 2 HSI 1 120 VAC DPDT MAIN POWER SWITCH S2 S2 35 67 35 67 L2 35 67 L2 35 67 BD 1 IGN S1 S1 35 67 35 67 35 67 L1 35 67...

Page 23: ...Mighty Therm2 Page 23 Figure 19 Mighty Therm2 500 750 Connection Diagram...

Page 24: ...LAARS Heating Systems Page 24 Figure 20 Mighty Therm2 1000 Connection Diagram...

Page 25: ...1 1 2 3 4 5 6 7 8 9 10 10 lockout indicator T stat lockout indicator G Pressure Switch Gas Valve 24V Ground Remote Sense S1 L1 L2 S2 Fenwal F1 F2 lockout indicator T stat lockout indicator G Pressure...

Page 26: ...e graves blessures ou la mort Ne faire seulement que les connexions conformes au Manuel d installation et d exploitation If controlling the stages of the MT2 from an external source multiple boiler co...

Page 27: ...ners independently Note that if a single blower is disabled on units 1250 2000 the other fan will continue to operate and safely allow the boiler to run with a single stage 6 2 Filling the System 1 En...

Page 28: ...ent and Set Up Mighty Therm2 appliances may be operated at high altitude 7700 ft 2347 m with a reduction in output of approximately 10 At altitudes of less than or more than 7700 ft 2347 m the applian...

Page 29: ...y Therm2 appliances for high altitude High altitude adjustment is accomplished by adjustment of the gas valve manifold pressure and the air shutter s The required instruments used to assist in these a...

Page 30: ...Disen gage the flanged fitting before and after the valve and remove the valve Re install in reverse order Ensure o rings are properly installed for both inlet and outlet Turn on manual gas shutoff va...

Page 31: ...onduit and sensors from all components that are attached to the inlet outlet header 4 Isolate the heat exchanger from the water supply 5 Disconnect the header flanges from the inlet and outlet 6 Allow...

Page 32: ...Laars representative to discuss possible remedies 8 4 Short Cycling Water Heater Short cycling will generally occur only in combination space heating and water heating applications when the water hea...

Page 33: ...019 5C3019 5C3019 5C3019 5C3019 5C3019 5C3019 12C Pump Housing Cover 5C3020 5C3020 5C3020 5C3020 5C3020 5C3020 5C3020 14 Cover Pipe Gas Manifold 5F3304 5F3304 10F3304 20F3304 20F3304 20F3304 20F3304 2...

Page 34: ...T2018000 T2017400 T2018000 T2017400 45 Tile Bottom Center T2015900 T2015900 T2015900 T2015900 1 1 2 2 Gas Train Components See Figure 24 46 Blower A2111900 A2111900 A2111900 A2111900 A2111900 A2111900...

Page 35: ...Cutoff optional E2076500 E2076500 E2076500 E2076500 E2076500 E2076500 E2076500 60 Gauge Temperature Pressure A0079000 A0079000 A0079000 A0079000 A0079000 A0079000 A0079000 62 Tee Adapter Outlet Cast...

Page 36: ...E0093200 E0093200 E0093200 79 Panel Mounting Limits Ignition Control 5F7001 5F7001 5F7001 5F7001 5F7001 5F7001 5F7001 80 Panel Cover High Limit Ignition Control 5F7003 5F7003 5F7003 5F7003 5F7003 5F7...

Page 37: ...Mighty Therm2 Page 37 Figure 23 Sheet Metal Components 12A 12B 12C...

Page 38: ...LAARS Heating Systems Page 38 Figure 24 Internal Components...

Page 39: ...2001800 1500 A2001900 1750 A2001900 2000 A2109700 Mighty Therm2 Water Heater Size Pump p n Soft Water Normal Water Hard Water 500 A2001700 A2001700 A2001900 750 A2001700 A2001700 A2001900 1000 A200170...

Page 40: ...8 0100 Fax 905 366 0130 www Laars com Litho in U S A Laars Heating Systems 1608 Document 1211J Figure 26 Electrical Components Laars Heating Systems Company reserves the right to change specifications...

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