Laars VW-PW Installation, Operation And Maintenance Instructions
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Laars VW-PW Installation, Operation And Maintenance Instructions

Laars VW-PW Installation, Operation And Maintenance Instructions

Mighty therm volume water heaters
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Installation, Operation and Maintenance Instructions
Installation, Operation
and Maintenance
Instructions for
Mighty Therm
Volume Water Heaters
Model VW-PW
Sizes 175-400
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.
WARNING
WHAT TO DO IF YOU SMELL GAS
Document 2051E

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Summary of Contents for Laars VW-PW

  • Page 1 Maintenance Instructions for Mighty Therm Volume Water Heaters Model VW-PW Sizes 175-400 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.

  • Page 2: Table Of Contents

    LAARS Heating Systems Page 2 TABLE OF CONTENTS SECTION 1. Hi-Limit Switch Checkout ......22 Shut-Down Procedure ......... 22 General Information Introduction ............ 3 SECTION 4. Warranty ............3 Technical Assistance ........3 Maintenance General Instructions ........22 SECTION 2.

  • Page 3: General Information

    The VW-PW heaters are offered in a basic 1.3 Technical Assistance configuration (see Figure 1). On PW heaters the pump is factory installed. On VW heaters the pump is field Consult Laars or your local wholesaler with any installed.

  • Page 4: Installation Instructions

    Remove the vent cap or drafthood from its package. Install the VW-PW heaters in accordance with the procedures in this manual (or the Laars warranty may be voided), local codes and ordinances. In the absence of such codes, install the heaters in accordance with the latest edition of the National Fuel Gas Code, ANSI Z223.1.

  • Page 5: Site Location

    Table 1 and Figure 8 Caution are met. Outdoor installations are not recommended in areas where the danger of snow blockage exists. VW-PW heaters can be installed in the standard low-profile, Indoors Outdoors grate top configuration as received from the factory,...

  • Page 6: Flooring - Typical Installation

    LAARS Heating Systems Page 6 Concrete slab must extend out a minimum of 12 in. (305mm) on all sides. LAARS UNIT (Side View) Base For Combustible Floors Roof - Wood and Steel Construction Figure 11. Standard base for combustible floor.

  • Page 7: Outdoor Air Supply

    (see Figure 14 and area of at least one square inch for each 4,000 BTU/h Table 2 ). Laars does not recommend indoor input of the total input rating of all appliances in the installations that do not provide combustion air from enclosed area.

  • Page 8: General Information

    Laars ships the VW heater with the water connections on the right side. The VW heater can be installed with the water connections on either side. It...
  • Page 9 Mighty Therm Volume Water Heaters Page 9 Figure 15. Heat exchanger reversal. Figure 16. Flue collector Holddown Clamps.
  • Page 10 LAARS Heating Systems Page 10 Remove the three grommets. Remove the four screws that fastens the metal channels covering the capillary tube on the right Remove the drain valves and plug. There is one side of the jacket, and lay the channels aside.

  • Page 11: Water Chemistry

    25. Feed the two brown wires through the top hole on the left side until the conduit elbow is against Laars equipment is designed to be used in a the jacket. variety of water conditions. With the proper pump, the 26.
  • Page 12 LAARS Heating Systems Page 12 Heat Flow Pressure* Water Temp Exch. Water Rate Drop Rise Model Passes Category ° ° Soft Normal 11.2 Hard 19.1 Soft Normal Hard 15.9 Soft Normal 11.2 Hard 19.1 Soft Normal Hard 15.9 Soft 12.5 Normal 12.5...
  • Page 13 Mighty Therm Volume Water Heaters Page 13 Figure 21. Hot water supply with vertical tank. Note: Heavy line indicates heater-to-tank circulation loop. Figure 22. Hot water supply with horizontal tank.

  • Page 14: Pump Requirements

    LAARS Heating Systems Page 14 2.6.5 Pump Requirements valve is directed to an open drain and protected from freezing. The VW heater does not have a factory installed pump (see Table 4 for pump performance require- Install a properly sized thermal expansion tank ments).

  • Page 15: Storage Tank Installation

    Mighty Therm Volume Water Heaters Page 15 Check the oil level in the pump before starting Distance from Gas Meter or Last Stage Regulator the heater. Oil the pump every three months. Oil pumps located in excessively hot or dusty 0-100 feet 100-200 feet 200-300 feet...

  • Page 16: Gas Supply And Piping

    Check the rating plate to make sure the heater is or locations where gas might collect. Locate heaters a fitted for the type of gas being used. Laars safe distance from LP gas storage and filling heaters are normally equipped to operate below a equipment.

  • Page 17: Combined Space Heating/Potable Water Heating Systems

    WARNINGS current (VAC). If 240 VAC, contact local factory Vent pipes, drafthoods, and heater tops get hot! representative or Laars. These surfaces can cause serious burns. Do not Wire the heater and pump exactly as shown in touch these surfaces while the heater is in the wiring diagram supplied with the heater.
  • Page 18 LAARS Heating Systems Page 18 IGNITION SYSTEM NO. 1 - STANDING PILOT ON/OFF OR MECHANICAL MODULATION Volume Water Heaters (325-400) Version B Natural or Propane Gas PUMP INCLUDED ON PW MODELS, FIELD SUPPLIED ON VW MODELS Figure 26. Typical example of wiring schematic, System 1.
  • Page 19 Mighty Therm Volume Water Heaters Page 19 IGNITION SYSTEM NO. 12 - ELECTRONIC IGNITION ON/OFF OR MECHANICAL MODULATION Volume Water Heaters (325-400) Version B Natural or Propane Gas PUMP INCLUDED ON PW MODELS, FIELD SUPPLIED ON VW MODELS Figure 27. Typical example of wiring schematic, System 12.

  • Page 20: Setting The Temperature Controls

    LAARS Heating Systems Page 20 hot water in the application. After a setting has been chosen for the tank temperature control, set the heater temperature control 10°F (6°C) higher. The heater’s temperature control senses the inlet water temperature to the heater. The heater’s manual reset high limit (and automatic reset...

  • Page 21: Adjustment For Minimum Input Rate (Models With Modulating Gas Valve)

    Mighty Therm Volume Water Heaters Page 21 Example, Metric units: If the heater’s Electronic Pilot Standing Pilot temperature control is set to 55°C, and the temperature rise through the heater is 14°C, the outlet temperature will be 69°C (55°C + 14°C). Set the automatic reset high limit to 80°C (69°C + 11°C) and set the manual reset high limit to 83°C (80°C + 3°C).

  • Page 22: Hi-Limit Switch Checkout

    LAARS Heating Systems Page 22 At startup and every 6 months after, look at the 3.5 Hi-Limit Switch Checkout pilot and main burner flame (see Figure 29). If After running the heater for a long enough the flame has the appearance of sooting tips, period, bring the water temperature within the range of check for debris near orifices.
  • Page 23 Mighty Therm Volume Water Heaters Page 23 If the gas valve is found to be defective, replace 11. Hold the gas burner or pilot burner firmly, and it by following these instructions. push it away from the manifold until it is clear of the orifice.

  • Page 24: Heat Exchanger

    To remove the heat exchanger, refer to Section gas and manifold regulated gas pressures. A 2.6.1. manometer kit is available from Laars and instructions for its use are included in the kit. A dry gas pressure gauge may also be used for either test.

  • Page 25: Checking The Manifold Regulated Gas Pressure

    Mighty Therm Volume Water Heaters Page 25 Attach one end of the manometer hose to the fitting on the gas valve and the other end to the manometer. Open gas supply valve to the heater to test. With the main burners firing, the manometer reading should be between 6.5 and 9 inches W.C.

  • Page 26: Testing The Transformer

    LAARS Heating Systems Page 26 Testing the transformer requires an AC voltmeter with a 50 volt (V) range. Test the transformer using the following procedures: Clip a lead from the voltmeter to the yellow wire terminal on the transformer. Touch the other lead to the red wire terminal (see Figure 35).

  • Page 27: Testing The Fuse

    Mighty Therm Volume Water Heaters Page 27 5.2.4 Testing the Manual Reset Hi-Limit Switch To test the manual reset hi-limit switch (see Figure 36): Touch the other lead of the voltmeter to both terminals of the manual reset hi-limit switch. The voltmeter should read 24 to 28VAC at both terminals.

  • Page 28: Testing The Ignition Control

    LAARS Heating Systems Page 28 5.2.7 Testing the Fuse If no sparking is heard, pull the ignition lead To test the fuse: from the ignition control and hold the bare terminal 1/8 to 3/16 inch (3.2 to 4.8 mm) from...

  • Page 29: Testing The Pilot Thermocouple (For Standing Pilot)

    Mighty Therm Volume Water Heaters Page 29 Thermocouple Thermocouple Adapter Gas Valve Pilot Millivolt Figure 42. Flame sensing current. Meter Clip one lead of a millivolt meter on the center Figure 41. Testing the pilot thermocouple. post of the tube and the other lead on the copper pilot thermocouple shield.

  • Page 30: Testing For Burner Ignition (For Standing Pilot)

    A smaller current could be provided by Laars. Determine whether or not an caused by poor pilot flame, the position of the external control is open by checking for voltage at pilot electrode, or bad cable and connectors.
  • Page 31 Mighty Therm Volume Water Heaters Page 31 Item Description Part Number Item Description Part Number Nat. Stdg Pilot, (Model 250) ....V0073300 WATER SYSTEM Nat. Stdg Pilot, (Model 325-400) ... V0049900 41. Bracket, Heat Exchanger ....... 10457000 LP IID, O/O,MM (Models 175 thru 400) V0073600 42.
  • Page 32 (Customer Service, Service Advisors) 20 Industrial Way, Rochester, NH 03867 • 603.335.6300 • Fax 603.335.3355 (Applications Engineering) 1869 Sismet Road, Mississauga, Ontario, Canada L4W 1W8 • 905.238.0100 • Fax 905.366.0130 www.Laars.com Litho in U.S.A. © Laars Heating Systems 0912 Document 2051E...

This manual is also suitable for:

Vw-pw175Vw-pw250Vw-pw325Vw-pw400

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