Laarsen Associates VW, PW, IW Troubleshooting and Analysis Service Problems, Heater will not Fire

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LAARS HEATING SYSTEMS

 

 

Lower the front of the burner (to avoid damaging pilot shield) then remove the burner tray.

Caution

Black carbon or green soot on a dirty heat exchanger can, under certain conditions, be ignited by a random spark or open flame. To prevent this unlikely occurrence, dampen the soot deposits with wet brush or fine water spray before servicing or cleaning the heat exchanger.

With a wire brush, remove soot and loose scale from heat exchanger. Clean fallen debris from bottom of heater. Make sure burner ports are clear and pilot assembly is free of debris.

d.Reassemble in reverse order:

Be sure the heat exchanger baffles are replaced.

8.The gas and electric controls installed on heaters are engineered for both dependable operation and long life, but the safety of this equipment completely depends on their proper functioning. It is strongly recommended that the basic items be checked by a competent serviceman every year and replaced when necessary. The basic controls are:

a.Water temperature controls.

b.Pilot safety system.

c.Automatic electric gas valve(s).

d.Flow sensing safety device.

9.Low water cutoffs should be inspected every six

(6) months, including flushing of float types.

NOTE: Warranty does not cover any damage caused by lack of required maintenance or improper operating practices.

10.Both modulating and stage valve are adjusted at the factory for minimum permissible rates and should not be readjusted.

SECTION 5.

Troubleshooting and Analysis of

Service Problems

1.For proper service and problem diagnosis of the heater and heater system, the following tools are required:

a.Gas pressure test kit with range from zero to 14 W.C. Either a slack tub manometer or an accurate gas pressure gauge is acceptable with proper adapters which will connect to the available fittings in the line and on the gas valve.

b.Multi-meter with the following ranges:

0 to 500 volts A.C.

0 to 1000 ohms continuity.

c.Tube cleaning kit consisting of reamer, stainless steel brush, speed handle and handle extensions.

d.Heater thermometer (with 1/2" NPT well) 100-240°F.

2.In addition, the heater should be equipped with a system pressure gauge with proper ranges for heater operation.

I. HEATER WILL NOT FIRE.

Possible Cause

What To Do

 

 

A. Electric power is off

A. Check to see that main power

 

switch is “ON.” Use testing

 

device to trace power to

 

heater junction box.

 

 

B. Operating or safety control

B. Turn off power. Use continuity

has opened circuit to electric

across terminals of each

gas valve.

operating and safety control

 

switch up to the electric gas

 

valve. Replace effective

 

control.

 

 

C. Pilot flame is out.

C. Relight pilot per instruction.

 

 

D. Manual reset device has

D. Follow instructions for start-

tripped.

up. Reset Pilot safety and all

 

manual reset safety switches

 

and reset manual safety gas

 

valve.

 

 

E. No gas pressure to burners.

E. Trace gas line to service

 

shutoff cock. If service cock is

 

open, trace gas line to meter.

 

If no pressure is present at

 

meter, call for public utility

 

service. If gas is present in

 

heater inlet, check pressures

 

in following sequence:

 

(1) downstream from pressure

 

regulator. (2) downstream

 

from electric gas valve.

 

Replace or adjust as

 

necessary.

 

 

F. Electric gas valve operator is

F. Disconnect wiring harness at

burned out or shortened.

gas valve terminals. Check

 

continuity to actuator coil. If

 

open circuit or short is

 

indicated, replace coil or

 

operator.

 

 

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Contents Mighty Therm Table of Contents 1B. Heater Identification General Information1A. Introduction Installation 2A. Heater Placement2B. Installation of Indoor Heaters 1C. Flow RequirementsInstallation on Concrete Blocks or Tile 2B-1. Combustion Air Supply 2C. Installation of Outdoor Heaters 2D. Gas Supply and Piping2E. Electrical Wiring 2F. Water Piping of System2G. Water Expansion Pressure Relief Valve Location2H. Pump Performance and Installation With Vertical Tank Horizontal Hot Water Supply System Model VW & PWSplit System Piping Diagram, Model IW Dual Installation Piping Diagram, Model IW With Horizontal Tank With Vertical TankMighty Therm Volume Water Heater 2J. Tank Installation 2K. Two-Temperature SystemOperation 2I. Water Pressure3B. Initial Start-Up 3C. To Start Up System Hi-Limit CheckoutMaintenance 3D. To Turn Off Heater3E. To Shut Down System Indoor ModelsTroubleshooting and Analysis Service Problems Heater will not FireIII. Water Dripping Firebox Numbers Parts Identification Laars Heating Systems Tile Assemblies Ignition Control, Electronic Safety Gas Valve, On-Off Two Stage Nat Plug, 3/4, Sq. Hd Outdoor Parts Outdoor Parts Descriptions and Order Numbers See Parts Illustration OnMighty Therm Volume Water Heater Energy Management Monitor EM2 Pump Rotating Sections and Repair PartsOptional Parts Descriptions and Order Numbers