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Installation, Operation and Maintenance Instructions
Installation, Operation
and Maintenance
Instructions for
Mighty Therm
LO-NOx
Volume Water Heater
Model VW-PW
Sizes 250/400
For Natural Gas Only
U.S. Reg. 1,483,289
Canada Reg. 333,796
FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,
qualified in hot water 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.
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.
• 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.
TM
WARNING
WHAT TO DO IF YOU SMELL GAS
Document 2137A
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Summary of Contents for Laars VW-PW Series
- Page 1 Installation, Operation and Maintenance Instructions Document 2137A Installation, Operation and Maintenance Instructions for Mighty Therm LO-NOx Volume Water Heater Model VW-PW Sizes 250/400 For Natural Gas Only U.S. Reg. 1,483,289 Canada Reg. 333,796 FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician, qualified in hot water heater installation and maintenance.
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Page 2: Table Of Contents
LAARS Heating Systems Page 2 TABLE OF CONTENTS SECTION 1. SECTION 3. General Information Operating Instructions Introduction ............ 3 Start-Up Procedure ........15 Warranty ............4 3.2. Setting the Temperature Controls ....15 3.2.1 Remote Water Heater Temperature Control ............15 SECTION 2. -
Page 3: General Information
General Information Mighty Therm water heaters must be installed in accordance with the procedures detailed in this manual, or the Laars Heating Systems warranty will 1.1 Introduction be voided. The installation must conform to the This manual provides installation, operating, and... -
Page 4: Warranty
The owner should fill The VW, PW heaters are design certified for out the warranty registration card and return it to Laars indoor installation when equipped with a special Heating Systems. - Page 5 Mighty Therm LO-NOx Volume Water Heater Page 5 Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Drafthood Switch Receptacle.
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Page 6: Site Location
LAARS Heating Systems Page 6 2.3 Site Location 2.3.1 Installation Information WARNING Improper installation or maintenance can cause nausea or asphyxiation from carbon monoxide in flue gases which could result in severe injury, property damage, or death. Closet Installation Room Installation... -
Page 7: Combustion And Ventilation Air Supply
(see Figure 20 and Drafthood Adequate Table 2 ). Laars does not recommend indoor Air Supply installations that do not provide combustion air from To Room outside the building. -
Page 8: Outdoor Air Supply
LAARS Heating Systems Page 8 Method 2: NOTE: Do not use sheet metal screws at the snap One permanent opening, commencing within 12" lock joints of Type B double-wall gas vents. (30 cm) of the top of the enclosure shall be permitted. -
Page 9: Inspection Of Commonly Vented Appliances
LAARS product, please call tous les ventilateurs d’extraction comme les Applications Engineering at (603) 335-6300. -
Page 10: Water Flow
See Table 4 for pump performance. 2.6.1 Water Chemistry PW heaters are not available for hard water applications. Laars equipment is designed to be used in a VW and PW heaters are not designed for applica- variety of water conditions. With the proper pump, the... -
Page 11: Pressure Buildup In Water System
Mighty Therm LO-NOx Volume Water Heater Page 11 Heat Flow Pressure* Water Temp Exch. Water Rate Drop Rise Model Passes Category ° ° Soft Normal 11.2 Hard 19.1 Soft 13.3 Normal 13.3 Hard 23.4 *Pressure drop includes head loss of heat exchanger and through 30 feet (9.1 m) of pipe and normal fittings when heater is installed with storage tank. - Page 12 LAARS Heating Systems Page 12 Optional Cold Water Supply Hot Water When Adequate Tank Opening to Building Not Available Hot Water Return from Heater Building Throttling Valve Drain Check Valve Bldg. Service Loop Valve Circ. Pump Pump To Drain Conventional...
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Page 13: Pressure Relief Valve
Check the rating plate to make sure the heater is Be sure the tank is suitable for the water in the fitted for the type of gas being used. Laars LO- system. Some water is corrosive and requires a NOx heaters are normally equipped to operate protected tank. -
Page 14: Electrical Wiring
LAARS Heating Systems Page 14 Distance from Gas Meter or Last Stage Regulator MANUAL SHUT-OFF VALVE 0-100 feet 100-200 feet 200-300 feet 0-30 m 30-60 m 60-90 m Boiler Nat. Nat. Nat. UNION Size SUPPLY 1¼ 1¼ 1½ INLET T-FITTING 1¼... -
Page 15: Operating Instructions
Mighty Therm LO-NOx Volume Water Heater Page 15 Connect all field-installed devices (draft If the unit is equipped with an automatic reset switches, relays, timers, outdoor temperature high limit, set the automatic reset high limit 20°F reset devices, etc.) to the heater wiring at points (11°C) above the outlet temperature to avoid nuisance labeled Field Interlock. -
Page 16: For Your Safety Read Before Operating
LAARS Heating Systems Page 16 FOR YOUR SAFETY READ BEFORE OPERATING WARNING: If you do not follow these instructions exactly, a fire or explosion may result, causing property damage, personal injury or loss of life. A. This appliance does not have a pilot light. It is •... -
Page 17: Instructions De Mise En Marche
Mighty Therm LO-NOx Volume Water Heater Page 17 POUR VOTRE SÉCURITÉ LISEZ AVANT DE METTRE EN MARCHE AVERTISSEMENT: Quiconque ne respecte pas à la lettre les instructions dans la présente notice risque de déclencher un incendie ou une explosion entraînant des dommages, des blessures ou la mort. - Page 18 LAARS Heating Systems Page 18 Figure 29. Mighty Therm LO-NOx, PW250.
- Page 19 Mighty Therm LO-NOx Volume Water Heater Page 19 Figure 30. Mighty Therm LO-NOx, VW250.
- Page 20 LAARS Heating Systems Page 20 Figure 31. Mighty Therm LO-NOx, PW/PH 400.
- Page 21 Mighty Therm LO-NOx Volume Water Heater Page 21 Figure 32. Mighty Therm LO-NOx, VW/HH 400.
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Page 22: Hi-Limit Switch Checkout
LAARS Heating Systems Page 22 If the unit is equipped with an automatic reset high limit, set the automatic reset high limit 20°F (11°C) above the outlet temperature to avoid nuisance lockouts. Set the manual reset high limit 5°F (3°C) above the automatic reset high limit. -
Page 23: Cleaning The Heat Exchanger
A manometer NOTE: While the heat exchanger is out of the heater, kit is available from Laars and instructions for its use inspect the firewall refractory insulation blocks for are included in the kit. A dry gas pressure gauge may cracks, wear, and breakage. -
Page 24: Checking The Manifold Regulated Gas Pressure
LAARS Heating Systems Page 24 Attach one end of the manometer hose to the 5.2 Electrical Troubleshooting fitting on the gas valve and the other end to the manometer. WARNING Open gas supply shutoff valve outside the heater Electricity can cause property damage, injury, or and follow the lighting instructions in Figures 27 loss of life. -
Page 25: Testing The Transformer
Mighty Therm LO-NOx Volume Water Heater Page 25 the short must be found and repaired. Do not jumper or bypass the fuse. Make sure the electrical circuit to the heater is Make sure the toggle switch on the right side of the heater is on. -
Page 26: Testing The Flow Switch
LAARS Heating Systems Page 26 Touch the other lead of the voltmeter to both Touch the other voltmeter lead to terminal terminals of the manual reset hi-limit switch. The number (1) one on the terminal strip. voltmeter should read 20 to 28VAC at both If there is no voltage, replace the fuse. -
Page 27: Heater Will Not Shut Off
6.1 Ordering Information ..............400 10861905 To order or purchase parts for Laars products, 33 Adapter Plate .......... 250 10535303 contact your nearest Laars dealer or distributor. If they ..............400 10535305 34 Clip ............All 10211000 cannot supply you with what you need, contact Laars 35 Flue Collector Hold Down Bracket .. - Page 28 Tee, Cast Iron .......... All P0071700 54 Bushing, Brass ........All P0018500 NOTE 1: The Laars LO-NOx heater is designed for operation 55 Heat Exchanger Support Bracket .... All 10457000 only with natural gas up to an altitude of 2000 feet. The 56 Flue Collector Hold Down Clamp ....
- Page 29 Mighty Therm LO-NOx Volume Water Heater Page 29 See next page for details Burner Tray (See next page for details)
- Page 30 LAARS Heating Systems Page 30...
- Page 31 Mighty Therm LO-NOx Volume Water Heater Page 31...
- Page 32 6000 Condor Drive, Moorpark, CA 93021 • 805.529.2000 • FAX 805.529.5934 20 Industrial Way, Rochester, NH 03867 • 603.335.6300 • FAX 603.335.3355 480 S. Service Road West, Oakville, Ontario, Canada L6K 2H4 • 905.844.8233 • FAX 905.844.2635 www.laars.com Litho in U.S.A. © Laars Heating Systems 0406 Document 2137A...
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