Laars VW-PW Series - User Manual

Installation, Operation and Maintenance Instructions Document 2137A
H0250000A
Installation, Operation
and Maintenance
Instructions for
Mighty Therm
TM
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.
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.
OUT OF
PRODUCTION

Summary

Installation Instructions

Installation General Information

Field Assembly Procedures

Site Location Requirements

Installation Information Details

Combustion and Ventilation Air Supply

Outdoor Air Supply Requirements

Indoor Air Supply Requirements

Venting Category I Information

Common Venting Systems Installation

Commonly Vented Appliances Inspection

Water Flow Considerations

Freeze Protection Measures

Pump Requirements

Pressure Buildup in Water System

Pressure Relief Valve Installation

Gas Supply and Piping

Gas Supply and Piping General Instructions

Electrical Wiring Requirements

Operating Instructions

Start-Up Procedure

Step-by-step instructions for safely starting the heater after installation.

Setting Temperature Controls

Guidance on setting the temperature controls for optimal operation and safety.

Hi-Limit Switch Checkout

Procedure to test the hi-limit switch operation by cycling the burners.

Shut-Down Procedure

Instructions for safely shutting down the heater, including freeze protection.

Maintenance Procedures

General Maintenance Instructions

Heat Exchanger Inspection

Details how to inspect the heat exchanger for scale buildup.

Heat Exchanger Cleaning

Provides instructions for cleaning the heat exchanger tubes and checking related components.

Troubleshooting and Service

Gas Pressure Tests

Procedures for testing main line and manifold gas pressures using a manometer.

Main Line Gas Pressure Check

Step-by-step guide to measure the main gas line pressure.

Manifold Regulated Gas Pressure Check

Instructions for checking the gas pressure at the manifold.

Electrical Troubleshooting Overview

Describes procedures for checking electrical power and control components.

Heater Does Not Come On Troubleshooting

Troubleshooting steps for when the heater fails to start.

Transformer Testing Procedure

How to test the transformer using an AC voltmeter.

Electrical Power Supply Testing

Procedures for testing the voltage supply to the heater's electrical components.

Manual Reset Hi-Limit Switch Test

Steps to test the manual reset hi-limit switch for proper function.

Flow Switch Testing

How to test the flow switch to ensure it operates correctly.

Fusible Link (Flame Roll-Out Switch) Test

Fuse Testing Procedure

Ignition Control Testing

Combustion Air Blower Inspection

Heater Will Not Shut Off Troubleshooting

Laars VW-PW Series Specifications

General

Category	Water Heater
Series	VW-PW
Fuel Type	Natural Gas or Propane
ASME Construction	Yes
Water Capacity	50 - 120 Gallons
Temperature Range	Adjustable up to 180°F
Dimensions	Varies with model, see specification sheet
Weight	Varies with model, see specification sheet