LAARS U.H.E. User Manual

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Page 1

Service Manual Document 11019A

Service Manual for

U.H.E.

Ultra High Efciency

Water Heaters

UHE60T125E*(NA,XA)(2)

UHE60T150E*(NA,XA)(2)

UHE60T199E*(NA,XA)(2)

UHE100T150E*(NA,XA)(2)

UHE100T199E*(NA,XA)(2)

UHE100T250E*(NA,XA)(2)

UHE100T300E*(NA,XA)(2)

UHE100T399E*(NA,XA)(2)

(*) Denotes Warranty Years

Troubleshooting Guide and Instructions for Service

These instructions are to be stored next to the boiler for reference purposes.

FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,

qualied in hot water boiler installation and maintenance. Improper installation and/or operation could create carbon monoxide gas in ue 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 re or explosion may result causing property damage, personal injury or loss of life.

Do not store or use gasoline or other ammable

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 re department.

Installation and service must be performed by

a qualied installer, service agency, or gas

supplier.

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 inammables 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

qualié ou par le fournisseur de gaz.

AVERTISSEMENT

Page 2

LAARS Heating Systems

U.H.E. Series Commercial Gas

Ultra High Efciency Water Heaters

Table of Contents

Page U.H.E.

Service Procedure

Introduction 3 - - -

How to use this manual 4 - - -

Tool required for service 4 - - -

Specifications 5 - - -

Sequence of Operation 8 - - -

Troubleshooting 10 - - -

Thermostat Circuit, Testing & Replacement 12 I

Combustion System Testing and Replacement 18 II

Burner Tube Inspection & Replacement 22 III

Gas Valve Replacement 24 IV

Blower Testing and Replacement 25 V

Exhaust Pressure Switch Testing and Replacement 27 VI

Hot Surface Igniter Testing and Replacement 30 VII

Flame Sensor Testing and Replacement 32 VIII

Ignition Module/Control Board Replacement 34 IX

Transformer Replacement 35 X

Vent Safety Switch Testing and Replacement 36 XI

Anode & Flue Baffle Inspection and Replacement 38 XII

Installation Check List 43 - - -

Heater Service Report 44 - - -

Parts List 45 - - -

Glossary of Terms 48 - - -

Page 3

U.H.E Service Manual

U.H.E. Series Commercial Gas

Ultra High Efciency Water Heaters

Introduction

The LAARS heating system Ultra High Efficiency Water Heater is designed to deliver a remarkable thermal efficiency rating in a quiet running unit with venting options that allow for installation flexibility. Several technologically advanced design features are incorporated in the design that will require additional knowledge on the part of the qualified service provider. The information in this manual will instruct service and maintenance professionals on the function, proper diagnosis and repair of LAARS Heating System Ultra High Efficiency Water Heater.

Page 3

The LAARS heating system Ultra High Efficiency Water Heater uses a low Nox premix power burner located at the top of the water heater to direct a turbulent flame down into a submerged combustion chamber. This turbulence causes a

thorough mixing of gas and air for optimum combustion. The combustion gases then travel through a three pass flue system keeping the gases moving at a high

velocity. The combination of high turbulence and velocity results in an optimum

transfer of heat from the flue gases into the water.

Burner operation is controlled using an electronic ignition module. The module monitors the status of the electronic thermostat, vent temperature limit switch, vent

system pressure switches and a flame sensor to control output voltage to blower motor, hot surface igniter and gas valve. The module contains programming which determines the sequence of operation and timings for purge periods, trial for ignition, flame sensing and lockout. The module will also provide diagnostic

information to help in determining the cause of system lockouts.

The contents in this manual are detailed informational tools to assist in the proper diagnosis of the Ultra High Efficiency Water Heater operational faults. Please read this service manual completely and provide as much information regarding the

Ultra High Efficiency Water Heater operation and installation specific concerns.

Page 4

It is intended for this manual to be used by qualified service personal for the primary purpose of troubleshooting analysis and repair of the LAARS heating system Ultra High Efficiency

Water Heater. Understanding the sequence of operation section of this manual will contribute greatly to troubleshooting this product.

An “Installation Check List” is shown on page 43. Compare the installation against the installation check list to confirm all requirements are met.

An “UHE Service Report” is shown on page 44. Completing this form will assist in the troubleshooting efforts. Should you need to call for technical support, Please provide the information shown on this form to the support technician to insure accurate troubleshooting.

Troubleshooting begins with “System Observation” to determine failure mode as indicated by the LED status of the ignition module. Troubleshooting continues with “Failure Modes and Probable cause” listed on page 10 directing the service provider to a series of test procedures to determine root cause of failure. Component replacement procedures directly follow the test procedures for a given component.

LAARS Heating Systems

In some difficult to diagnose conditions, it may be necessary to isolate the heater from the vent system to determine root cause.

Contact Technical support immediately if diagnosis is not determined using the methods described in this service manual.

Tools Required for Service

Manometer: Two types available, a liquid “U” tube type or a digital (magna-helic)

type. This device is used to measure gas and/or air pressures and vacuum.

Multi-Meter: A digital type is strongly recommended. This device is used to measure

electrical values. The meter you select must have the capability to measure volts AC, volts DC, Amps, micro-amps and ohms.

Thermometer: Used to measure water temperature. An accurate thermometer is

recommended.

Water Pressure Gage: Used to measure water supply pressure. Also used to determine tank

pressure by adapting to the drain valve of the heater.

Jumper Leads: A length of wire (12" min.) with alligator clip at both ends.

Various Hand Tools: Pipe wrench, channel locks, open end wrench set, 12" crescent wrench,

Allen wrench set, torx bit set, screw drivers (common & phillips), long reach (12") magnetic tip phillips head screw driver #2 tip, ¼" nut driver, pliers (common & needle nose), socket set including a 1-1/16 deep well socket, wire cutters, wire strippers, wire crimpers, torpedo level, small shop vac, step ladder, and flashlight.

Page 5

U.H.E Service Manual

Page 5

Model No

UHE60T125 UHE60T150

UHE60T199 UHE100T150 UHE100T199 UHE100T250 UHE100T300 UHE100T399

Input

Rate

BTU/h

125,000 150,000 199,999 150,000 199,999 250,000 300,000 399,999

1stHr

Del

Gal

100°F

Rise

187 211 265 250 309 364 405 521

363.6

422.7

557.6

450.5 597

734.8

836.4

1,127

Recovery GPH at Degree Rise

145.5

169.1 223

180.2

238.8

293.9

334.5 451

140°F100°F40°F

103.9

120.8 158 129 171 210 239 322

Stg

Cap

U.S.

Gal

60 60

60 100 100 100 100 100

Therm

Eff

96.0

93.0

92.0

99.1

98.5

97.0

92.0

93.0

57 57

57 77 5/8 77 5/8 77 5/8 77 5/8 77 5/8

Dia

28 ¼ 28 ¼ 28 ¼ 28 ¼ 28 ¼ 28 ¼ 28 ¼ 28 ¼

Flr

Vent

Outlet

5 5 5 5 5 5 5 5

Flr to

Inlet

Wtr

Conn

13 13 13 13 13 13 13 13

DIMENSIONS (INCHES)

Flr To

Flr to

Outlet

T&P

Wtr

Valve

Conn

42 ¼

62 ¼

Flr. To

Air

Intake

52 ½ 52 ½ 52 ½

73 1/8 73 1/8 73 1/8 73 1/8 73 1/8

Flr to

Gas

Conn

53 ½ 53 ½ 53 ½ 74 ¾ 74 ¾ 74 ¾ 74 ¾ 73 ¼

Front

Wtr

Conn

Dia

1 ½ 1 ½ 1 ½ 1 ½ 1 ½ 1 ½ 1 ½ 1 ½

Space

Heating

Conn

Dia

1 1 1 1 1 1 1 1

Gas

Conn

Dia

(NPT)

¾ ¾ ¾ ¾ ¾ ¾ ¾

T&P

Valve

Open (NPT)

Shpg

(lbs)

570

900

950

Page 6

Power supply Dedicated 120 VAC, 60 Hz, 15A, GFI

Gas Supply

Approved Gas Type Natural or Propane. Unit must match gas type supplied.

Gas Pressure (Nat & L.P.) 14.0" W.C. maximum static, 4.5" W.C. minimum running (recommend 7.0" W.C. min running)

Venting System Power vent, balanced direct vent or unbalanced direct vent. See vent tables on page 7

Approved Vent Materials PVC, CPVC or ABS

Minimum Clearance for Servicing

Maximum Water Supply Pressure

Thermostat Sensor 11,900 Ohms @ 70°F, ECO opens @ 201°F Max., ECO close @ 100°F Min.

Temperature Dial Min. set point 5400-6600 ohms, Max set point 0-50 ohms.

Thermostat Board Max temp 180°F, Min temp 91°F, 24VAC, 60Hz max.

Ignition Module See page 9

Transformer 120VAC primary, 24VAC secondary, 40VA.

Hot Surface Igniter 120VAC, 30-120 ohms @ room temperature.

Flame Sensor Output Minimum 1 micro amp, Typical range 4 to 7 micro amps.

Gas Valve Negative regulation, 24 VAC, ½" PSI max., 4.5" W.C. Minimum running inlet.

Minimum 1" NPT for UHE100T399, all others ¾" NPT (schedule 40 black iron pipe recommended)

18" from top, 24" from front, 4" sides and rear.

150 PSI

LAARS Heating Systems

Vent Safety Switch Normally closed, opens @ 350°F, manual reset.

Blocked Vent Pressure Switch

Blower 120VAC, 60Hz, .6-1 amps, 6400 RPM.

Combustion Levels CO2: 10-11%, CO: less then 0.04 percent (400 PPM) air free

24VAC, normally closed, opens when pressure increases to +2.70 W.C.

Page 7

U.H.E Service Manual

Page 7

Vent Tables

Balanced Direct Vent Systems

PVC, CPVC

Total length of intake piping and exhaust piping

added together must not exceed “Maximum

Combined Length”

Shown below

Maximum Combined Length (feet)

Model Number 3"

UHE60T125, UHE100T150 120'

UHE60T150, UHE100T199

UHE60T199 80' 130'

UHE100T250

UHE100T300

UHE100T399 50' 100'

Unbalanced Direct Vent Systems

Air intake CAN NOT exceed exhaust

by more than 30 feet

100'

80'

60'

170'

150'

130'

110'

Power Vented Systems

PVC, CPVC

Total length of exhaust piping must not exceed

“Maximum Vent Length”

Shown below

Maximum Vent Length (feet)

Model Number 3"

UHE60T125, UHE100T150 120'

UHE60T150, UHE100T199

UHE60T199

UHE100T250 80' 130'

UHE100T300

UHE100T399 50' 100'

100'

80'

60'

170'

150'

130'

110'

Notes:

1) Multiply the total number of 90° elbows (intake and exhaust) by 5 feet. Do not include the termination fittings or 3" condensate elbow.

2) Multiply the total number of 45° elbows (intake and exhaust) by 2 ½ feet.

3) Add this to the total length of straight pipe - intake and exhaust.

4) The sum total of all elbows and straight pipe - intake and exhaust must not exceed maximum lengths from tables above.

Example: UHE100T199 A 3" Balanced Direct vent system has 30 feet of straight exhaust pipe and 30 feet of straight intake pipe. It has 3- 90° elbows in the exhaust and 3- 90° elbows in the intake. It has 1- 45° elbow in the exhaust and 1- 45° elbow in the intake.

Therefore: 6- 90° elbows x 5 feet = 30 feet. 2- 45° elbows x 2½ feet = 5 feet. 60 feet of straight pipe + 30 feet + 5 feet = 95 feet. System is within “Maximum Combined Length” from table above.

Page 8

Thermostat calls for heat.

LAARS Heating Systems

Prior to energizing blower, ignition module checks to make sure the vent temperature switch is in the normally closed position. If the vent temperature switch is open, the control waits indefinitely for the temperature switch to close.

Blower energizes, pressure switch contacts are normally closed. If the pressure switch contacts are open, blower operates for up to 5 minutes waiting for contacts to close, then blower stops and flashes red PURGE LED indicating lock-out condition.

Blower pre-purge period (5 seconds) indicated by PURGE LED on the module

Igniter warm up (18 seconds), indicated by the IGNITER LED on the module. Note: The blocked vent pressure switch must be in the normally closed position for the ignition cycle to start.

Trial for Ignition (4 seconds, 3 trials).

a) Flame establishing period (2.5 seconds), gas valve and igniter on, indicated by the IGNITER and VALVE LED on the

module.

b) Burner on, flame proving period (1.5 seconds, looking for minimum of 1 micro amps), indicated by the FLAME &

VALVE LED on the module.

Steady state operation.

Ignition module monitors:

- Thermostat circuit.

- When thermostat opens, gas valve is shut down and post purge begins.

- Safety circuit.

- If vent temperature switch opens, gas valve is shut down, system will post purge and wait for switch to close before attempting re-ignition.

- If the blocked vent pressure switch opens, indicating a blocked exhaust vent condition, the gas valve is shut down, blower shuts down for 30 seconds and is re-energized and system attempts re-ignition if the pressure switch is closed. Blower operates for 5 minutes to wait for pressure switch to close, then shuts off with purge light flashing (lock-out). Will restart in 1 hour to attempt to close the switch and restart ignition sequence.

- Flame sensor circuit.

- If flame is lost, gas valve is shut down, system will post purge and system attempts re-ignition.

Thermostat satisfied.

Burner off.

Blower post purge (15 seconds).

Page 9

U.H.E Service Manual

Lockout Conditions

Lockout conditions: The system will go into lock out mode for the following reasons: Blocked vent pressure switch contacts open: Check for obstruction in exhaust pipe and vent terminal. Check for blocked condensate trap or drain line. In cold climates, make sure drain is not frozen. No ignition after 3 attempts:

a) Check inlet and outlet gas pressures (pressure taps located on top of gas valve). b) Igniter resistance too high (lower resistance preferred < 150 ohms). c) Misadjusted veturi screw (should be 6.5 turns out from bottom). d) Flame sense microamp not present (1.0 microamps minimum, should be 5 microamps or more). If burner lit,

check flame rod for deposits.

e) Check burner tube condition. Refer to section UHE-III for Burner Tube Inspection and Replacement.

Ignition Module Specifications

Control Functions:

- Ignition & heating functions in response to thermostat.

- Hot surface ignition using a microprocessor to control timing, flame sensing using flame rectification & ignition

retries.

- Monitoring of system pressure switches and limit switches.

- Control of gas valve, inducer motor, and hot surface igniter element based on thermostat demand and status of

safety inputs.

- Diagnostic indicators to provide information on power to control and control status.

- Non-interchangeable polarized plug-in connectors for all interconnections.

Page 9

Control Inputs:

- Thermostat call for heat.

- Blocked vent pressure switch (normally closed)

- Flame sensing.

- Low voltage supply.

- Line voltage supply.

IGNITION MODULE

Control Outputs:

- Inducer motor

- Hot surface igniter

- Gas valve

- Status indicator LEDs

Power - Green

Purge - Red

Igniter - Red

Valve - Red

Flame - Red

WIRING DIAGRAM

Page 10

LAARS Heating Systems

System Observation

Is front panel power

switch light on,

indicating power?

Is ignition module

power light on?

Position front panel

power switch to

“ON” position.

Is there 120VAC

across switch?

(see photo at right)

Is there 120VAC

across terminal block?

(see photo at right)

Determine power source

problem and correct.

Refer to ignition module

illustration, is there 120VAC

going to module at locations

P7(1) and P7(3)?

Replace ignition module.

(see page 24)

WARNING

120 volt potential exposure. Use caution

making voltage checks to avoid personal injury.

Power Switch

Light burned out,

replace switch.

Terminal Block

Repair/replace wire

harness to switch.

Refer to ignition module

illustration, is there 120VAC

between P1(1) and P1(3)?

Replace ignition module.

(see page 24)

Refer to ignition module

illustration, is there 24VAC

going to module at locations

P2(1) and P2(2)?

Replace transformer.

(see page 35)

Is ignition module

power and flame light

flashing?

Reset heater by

interrupting power.

IGNITION MODULE

Supply voltage polarity is

incorrect.

Reestablish power and

Adjust thermostat to

call for heat,

tank must be cold.

Allow heater to run

through heating cycle.

Did heater complete

heating cycle and did

blower post purge?

System is OK.

See next page

Page 11

U.H.E Service Manual

Determine failure mode by observing flashing LED status on ignition module.

* Denotes conditions that may require the water heater to be isolated from the vent

LED STATUS

Only power light

is on and water heater

will not function.

Page 11

LED status & probable cause

For models with Hot Surface Ignition

LED status and probable cause shown below.

system to determine root cause.

Probable Cause*

Exhaust pressure

switch. (see page 27)

LED STATUS

Purge light flashing.

Probable Cause*

Exhaust pressure

switch. (see page 27)

LED STATUS

Valve light flashing.

Probable Cause

Hot surface igniter.

(see page 30)

Probable Cause

Thermostat circuit.

(see page 12)

Probable Cause

Blower.

(see page 25)

Probable Cause*

Combustion system.

(see page 18)

Probable Cause

Vent safety switch.

(see page 36)

Probable Cause

Flame sensor. (see page 32)

LED STATUS

Power & flame

light flashing.

Probable Cause

Supply voltage

polarity.

Page 12

LAARS Heating Systems

IMPORTANT NOTE: This procedure assumes a cool tank

WARNING

Rotate temperature

dial to highest setting.

120 volt potential exposure. Use

caution making voltage checks

to avoid personal injury.

Refer to ignition module

illustration, Is there 24VAC between P3(7) and P3(8)?

Thermostat

not calling

OK, thermostat is

calling for heat.

Red Wire

(N.O.)

IGNITION MODULE

Yellow Wire

(COM)

Disconnect YELLOW and RED wires from the

thermostat board at location N.O. and COM shown in

photo at right. Use a jumper to connect these two

Turn off power to heater.

wires together as shown in photo at right.

Restore power to heater.

Did heater cycle on?

Check thermostat sensor

for proper resistance

(OHMS) across blue wires.

(See page 13)

Are readings correct?

(see photo at right)

Check sensor harness

continuity.

Is there continuity?

Check temperature dial for

proper resistance (OHMS)

(See Appendix B,

temperature dial resistance)

Are readings correct?

(see photo at right)

Replace

thermostat sensor.

(see page 12)

Replace harness.

Replace temperature dial

(potentiometer).

(see page 16)

See page 14

Yellow & Red

wires shown

jumpered

Thermostat

Sensor

Temperature Dial

Check temperature dial

harness continuity. Is there continuity?

Replace thermostat

circuit board.

(see page 15)

Replace harness.

Page 13

U.H.E Service Manual

°F012345678 9

Example: If temperature of sensor is 84°F, then the resistance through the sensor would be 8449 (see shaded area).

Page 13

APPENDIX - A

Sensor Resistance at Various Temperatures

Be Careful When Making Voltage Measurements or Jumping Terminals

Not to Damage or Deform Connectors or Connector Pins.

Draw Water From The T&P Valve. Compare Temperature With

Temperature Ohms Chart Below.

NOTE: Sensor resistance increases as the temperature falls.

In Degrees F

40 26109 25400 24712 24045 23399 22771 22163 21573 21000 20445 50 19906 19383 18876 18383 17905 17440 16990 16553 16128 15715 60 15314 14925 14548 14180 13823 13477 13140 12812 12494 12185 70 11884 11592 11308 11032 10763 10502 10248 10000 9760 9526 80 9299 9078 8862 8653 8449 8250 8057 7869 7685 7507

90 7333 7165 7000 6839 6683 6531 6383 6238 6098 5961 100 5827 5697 5570 5446 5326 5208 5094 4982 4873 4767 110 4663 4562 4464 4368 4274 4183 4094 4006 3922 3839 120 3758 3679 3602 3527 3453 3382 3312 3244 3177 3112 130 3048 2986 2925 2866 2808 2752 2697 2643 2590 2538 140 2488 2439 2391 2344 2298 2253 2209 2166 2124 2083 150 2043 2004 1966 1928 1891 1856 1820 1786 1753 1720 160 1688 1656 1625 1595 1566 1537 1509 1481 1454 1427 170 1402 1376 1351 1327 1303 1280 1257 1235 1213 1191 180 1170 1150 1129 1110 1090 1071 1053 1035 1017 999 190 982 965 949 933 917 901 886 871 857 842 200 828 814 801 788 775 762 749 737 725 713

APPENDIX - B

Temperature Dial Resistance

Proper Readings Should Be 5400-6600 Ohms at Minimum Setting

And 0-50 Ohms at Maximum.

Be Careful When Making Voltage Measurements or Jumping Terminals

Not to Damage or Deform Connectors or Connector Pins.

Page 14

LAARS Heating Systems

Thermostat circuit.

(continued from page 12)

Refer to ignition module

illustration, Is there 120VAC

between P1(1) and P1(3)?

Refer to ignition module

illustration, Is there

22 - 27VAC between

P2(1) and P2(2)?

Check AC source to

determine why there is no

illustration, Is there 120VAC

between P7(3) and P7(1)?

power.

Replace

ignition module.

(see page 34)

Refer to ignition module

Replace transformer.

(see page 35)

WARNING

120 volt potential exposure. Use caution

making voltage checks to avoid personal injury.

IGNITION MODULE

Red Wires

(Temperature Sensor)

Refer to ignition module

illustration, Is there 24VAC

between P3(9) and P2(1).

Replace ignition module.

(see page 34)

Check continuity through

ECO, red wires of

thermostat sensor.

Check at temperature

less than 160°F Is there continuity? (see photo at right)

Check wire harness

continuity. Replace

thermostat sensor or wire

harness as necessary.

(see page 17)

Replace thermostat

circuit board.

(see page 15)

Page 15

U.H.E Service Manual

Thermostat Board Replacement Procedure

Page 15

Step 1. Position main power switch to “OFF”

Step 2. Disconnect (unplug) water heater from 120

volt power source.

Step 3. Un-latch and remove top surround cover

from top of heater.

Step 4. Locate thermostat board on control panel.

(see photo at right)

Thermostat

Board

Step 5. Carefully disconnect all wires from thermostat

board.

Note: it may be necessary to identify wires

for proper re-connection.

Step 6. Remove the two screws (Phillips head screw

driver) that secure thermostat board to control panel.

Step 7. Install new thermostat board to control panel using

screws from step 6.

WARNING

120 volt potential exposure. Isolate the

appliance and reconfirm power is

disconnected using a multi-meter.

Mounting

screw locations

Step 8. Carefully reconnect wiring per the wire

diagram below. Reconfirm wire

connections are correct prior to putting

heater back in service

Step 9. Restore 120 volt power supply to water

heater and confirm proper operation following the lighting instructions on the lighting instruction label or the lighting instruction located in the installation and operating

instruction manual.

Step 10. Replace surround cover on top of heater.

WIRING DIAGRAM

Page 16

LAARS Heating Systems

Thermostat Potentiometer Replacement Procedure

Step 1. Position main power switch to “OFF”

Step 2. Disconnect (unplug) water heater from

Step 3. Un-latch and remove top surround cover

Step 4. Loosen set screw of adjusting

Step 5. Remove retaining nut (½" wrench)

Step 6. From inside of surround area, remove potentiometer

120 volt power source.

from top of heater.

Temperature

Adjusting Knob

knob (small blade screw driver) and remove adjusting knob from potentiometer. (see photos at right)

and washer from potentiometer. (see photos at right)

with gasket from side of surround. Notice how indexing tab on potentiometer assembles into locating hole of surround. (see photos below)

Indexing

Tab

Locating

WARNING

120 volt potential exposure. Isolate the

appliance and reconfirm power is

disconnected using a multi-meter.

Loosen set screw

with small blade

screw driver

Remove

retaining nut

Hole

Step 7. Disconnect potentiometer wire leads.

(see photo at right)

Step 8. Install new potentiometer with gasket into side of surround. Be sure to assemble with

indexing tab inserted into locating hole on side of surround (see photos above).

Step 9. Reconnect wires to potentiometer. Note: Wire leads are interchangeable with either wire.

Step 10. Restore 120 volt power supply to water heater and confirm proper operation following

the lighting instructions on the lighting instruction label or the lighting instruction located

in the installation and operating instruction manual.

Step 11. Replace surround cover on top of heater.

Potentiometer

Wire Leads

Page 17

U.H.E Service Manual

Thermostat Sensor (Thermistor) Replacement Procedure

Page 17

Step 1. Position main power switch to “OFF”

Step 2. Disconnect (unplug) water heater from

120 volt power source.

Step 3. Drain water heater down to a point below the

top of the tank.

Step 4. Un-latch and remove top surround cover

from top of heater.

Step 5. Fold back insulation just in front of burner to

expose temperature sensor (see photo below).

Step 6. Disconnect temperature sensor from

harness (see photos at right).

WARNING

120 volt potential exposure. Isolate the

appliance and reconfirm power is

disconnected using a multi-meter.

Disconnect sensor

from harness

Hot Surface Ignition Models

Insulation folded back

to expose temperature

sensor

Step 7. Remove temperature sensor (1-1/16" hex, deep well socket) from heater.

Note: Using a deep well socket will allow room inside socket

for sensor connector and wires.

Step 8. Apply thread sealing tape or applicable thread lubricant to threads of new sensor. Install new thermostat

Step 9. Fold insulation back into place. Be sure there are no wires in contact with burner.

Step 10. Restore 120 volt power supply and water supply to water heater, check and repair any

Step 11. Replace surround cover on top of heater.

sensor and Connect to wire harness from step 6.

leaks found. Confirm proper operation following the lighting instructions on the lighting

instruction label or the lighting instruction located in the installation and operating

instruction manual.

Page 18

LAARS Heating Systems

Observe burner operation through the sight glass located on the combustion insert mounting flange. Normal burner operation should ignite smoothly, without evidence of coughing or huffing upon ignition. The burner flame should be a blue flame near the burner surface in a uniform flame pattern. Occasional yellow or white streaks are normal.

Note: On higher input models using metal fiber mesh burner (serial number “CK” and later) a red glow from the burner surface is normal.

Verify Minimum Gas Supply Piping Requirements of: Minimum 1" NPT for UHE100T399, all others use ¾" NPT. (Schedule 40 black Iron Pipe recommended).

With manometer, check inlet

gas pressure. Is it stable

between 7" & 14" W.C. static?

(heater not running)

(see illustrations at right)

Does inlet gas pressure

drop more than 2" W.C.

during burner ignition?

Inadequately

sized regulator.

Is gas supply pressure regulator adjustable to

maintain proper and

stable setting?

WARNING

120 volt potential

exposure. Use caution

making voltage checks to

avoid personal injury.

Do you see the igniter

glowing through burner

site glass during the

warm up period?

Refer to ignition module illustration below,

is there 120VAC across terminals

P6(1) and P6(2)?

(Note: Igniter LED must be lit during this check).

Reconfigure gas

supply piping

inlet gas pressure tap will

immediately allow gas to

Replace ignition module.

(see page 34)

Adjust gas

supply regulator

WARNING

Removing screw from

flow from pressure tap.

Volt meter set to

OHM setting

Venturi

adjustment

Inlet gas

pressure tap

IGNITION MODULE

Is igniter resistance

less than 150 Ohms

(cold)?

(see check igniter

illustration)

Proceed to next page

Replace

hot surface igniter.

(see page 30)

Meter probe

Hot surface

igniter

CHECK IGNITER

RESISTANCE

Page 19

U.H.E Service Manual

Page 19

WARNING

120 volt potential exposure. Isolate the

Continued from

appliance and reconfirm power is

disconnected using a multi-meter.

Refer to ignition module illustration below,

is there 24VAC between P3(2) and P3(5) (blue and

brown wires) during the flame establishing period?

(Note: Valve LED must be lit during this check)

Can you hear or feel

gas valve energize?

Turn VENTURI set screw clockwise until its

bottomed out. Turn screw counter-clockwise 6-½

turns from bottom (see illustration below). Note:

UHE100T399 models do not have a venturi screw.

The gas regulator setting should be 1 - 1 ¼ turns

out from bottom.

Does burner light

smoothly, without

evidence of coughing

or huffing?

Check for obstruction

at inlet of gas valve.

Call for technical

Replace Rectifier harness and/or

Is inlet free of

obstruction?

support

Replace

ignition module.

(see page 34)

gas valve.

(see page 24)

Clear obstruction

adjustment

Venturi

IGNITION MODULE

Inspect burner tube, (see page 22)

Inlet gas

pressure tap

Does flame LED on the module

light and stay lit?

Check flame sensor,

Is there 1 to 5 micro amps

(min.) during 1.5 second

flame proving period?

(see page 32)

Replace flame sensor

(see page 32)

Does burner operate

normaly until thermostat is

satisfied?

System OK

Gas valve regulator

UHE100T399

Only

Page 20

LAARS Heating Systems

WARNING

Heater components may be HOT when performing the following steps in this procedure.

Take necessary precaution to prevent personal injury.

Combustion System Removal Procedure

Step 1. Position main power switch to “OFF”.

Step 2. Disconnect (unplug) water heater from

120 volt power source.

Step 3. Turn off gas supply to water heater.

Step 4. Un-latch and remove surround cover from top of

heater.

Step 5. From the gas valve, disconnect the gas

connection, PVC venting, Silicone tubing and wire harness.

Step 6. Disconnect wire harnesses flame sensor and

Blower. Disconnect wire harness from hot surface igniter.

Burner mounting

screw

(Total of 5)

WARNING

120 volt potential exposure. Isolate the

appliance and reconfirm power is

disconnected using a multi-meter.

Gas valve

wire harness

Gas

connection

PVC vent

connection

Step 7. Remove the 5 bolts (½" socket)

holding the burner mounting insert in place.

Step 8. Carefully remove combustion assembly

with gasket from water heater.

Step 9. See next page for combustion system installation procedure.

Burner mounting

insert

Burner tube

Burner mounting

insert gasket

Page 21

U.H.E Service Manual

Combustion System Replacement Procedure

Step 1. Fully inspect burner mounting insert gasket for the following:

a) Tears d) Dirt or debris b) Missing material e) Other imperfections that would inhibit proper seal c) Cracks

If gasket is NOT affected by any of the above, gasket replacement is not required.

Step 2. Install combustion assembly using new gasket or fully inspected gasket from step 1.

Secure combustion assembly at the burner mounting insert using screws from step 6 on previous page. Tighten screws evenly.

Step 3. Reconnect wire harnesses to hot surface igniter, flame sensor, blower and gas valve.

Page 21

Step 4. Reconnect PVC venting, gas supply and silicone tubing to gas valve. Turn on gas

supply to heater and check for gas leaks, repair any gas leaks found.

Step 5. Restore 120 volt power supply to water heater and confirm proper operation following

the lighting instructions on the lighting instruction label or the lighting instruction located in the installation and operating instruction manual.

Step 6. Replace surround cover on top of water heater.

Burner mounting

screw

(Total of 5)

PVC vent

connection

Burner mounting

insert

Gas valve

wire harness

Gas

connection

Burner tube

Burner mounting

insert gasket

Page 22

LAARS Heating Systems

WARNING

Heater components may be HOT when performing the following steps in this procedure.

Take necessary precaution to prevent personal injury.

Burner Tube Removal Procedure

Step 1. Position main power switch to “OFF”.

Step 2. Disconnect (unplug) water heater from

120 volt power source.

Step 3. Turn off gas supply to water heater.

Step 4. Un-latch & remove surround cover from top of

heater.

Step 5. From the gas valve, disconnect

the gas connection, PVC venting, wire harness and silicone tubing.

Step 6. Disconnect wire harness from

blower assembly.

Step 7. Remove the two screws holding

each the hot surface igniter and flame sensor in place (long reach

magnetic Phillips screw driver). Carefully remove hot surface igniter

and flame sensor from combustion

assembly.

WARNING

120 volt potential exposure. Isolate the

appliance and reconfirm power is

disconnected using a multi-meter.

HOT SURFACE

IGNITER/SPARK

ROD

BURNER TRANSITION

MOUNTING NUTS

Step 8. Remove the 4 nuts (7/16" wrench) holding

the burner transition in place. Lift the blower/gas valve transition assembly from burner mounting insert, remove gasket and set aside.

Step 9. Remove burner tube from burner

mounting insert. See next page for burner tube inspection procedure.

Page 23

U.H.E Service Manual

WARNING

Heater components may be HOT when performing the following steps in this procedure.

Take necessary precaution to prevent personal injury.

Burner Tube Inspection

Page 23

Step 1. Inspect burner tube as follows (BSI ceramic fiber mesh burner, water heaters prior to

Step 2. If burner tube is affected by any of the above, replacement is required. Refer to burner

serial number “CK”) :

a) Visually inspect ceramic fiber mesh, mesh should be uniform in appearance without large

gaps, tears or fraying. Mesh should have uniform pattern allowing for unrestricted gas flow.

b) Gently squeeze burner tube, Burner tube should feel firm without any soft areas

around the sides or at the bottom.

c) Visually inspect inside burner tube, Burner tube should be intact with no areas of

deterioration. Ports should be free of any debris.

Inspect burner tube as follows (Acotech metal fiber mesh burner, water heaters with “CK” serial number or later).

a) Outer fiber mesh should be uniform with no tears or deterioration.

tube replacement procedure below.

Burner Tube Replacement Procedure

Note: New metal fiber mesh burner (Acotech) is the replacement burner for the BSI ceramic fiber sock burner. The length of burner will not be the same as the previous BSI burner. Provide the model and serial number for the correct replacement burner.

Step 1. Fully inspect burner flange gaskets, igniter and flame sensor gaskets for the following:

a) Tears d) Dirt or debris b) Missing material e) Other imperfections that would inhibit proper seal c) Cracks

If gaskets are NOT affected by any of the above, gasket replacement is not required.

Step 2. Install burner tube with gaskets into burner mounting insert. Be sure gasket surfaces are free

of debris.

Step 3. Reconnect the blower/gas valve/transition assembly to burner mounting insert. Secure using

nuts from step 8 on previous page.

Step 4. Carefully reinstall flame sensor with gasket and hot surface igniter with gasket and secure with

screws from step 7 on previous page. Reconnect wire harnesses to sensor and igniter.

Step 5. Reconnect wire harnesses to blower motor and to gas valve.

Step 6. Reconnect PVC venting, gas supply and silicone tubing to gas valve. Turn on gas to heater

and check for gas leaks, repair any gas leaks found.

Step 7. Restore 120 volt power supply to water heater and confirm proper operation following the

lighting instructions on the lighting instruction label or the lighting instruction located in the

installation and operating instruction manual.

Step 8. Replace surround cover on top of water heater.

Page 24

Gas Valve Replacement Procedure

Step 1. Position main power switch to “OFF”.

Step 2. Disconnect (unplug) water heater from

120 volt power source.

Step 3. Turn off gas supply to water heater.

LAARS Heating Systems

WARNING

120 volt potential exposure. Isolate the

appliance and reconfirm power is

disconnected using a multi-meter.

Step 4. Un-latch & remove surround cover from top of

Step 5. From the gas valve, disconnect

Step 6. Remove the 2 gas valve mounting screws (Torx bit) located at the

Step 7. Remove any residual gasket material from blower and venturi mounting flange.

heater.

the gas connection, PVC venting, wire harness and silicone tubing.

11:00 O-clock & 5:00 O-clock position on the venturi mounting flange and remove gas valve from water heater.

Blower / gas valve

gasket

Blower

Venturi

mounting flange

Venturi inlet

Gas valve

wire harness

Gas valve assembly

Gas valve

mounting screws

(2 places)

Step 8. Install new gas valve with new gasket provided. Secure gas valve in place using

screws from step 6.

Step 9. Reconnect PVC venting, gas supply, silicone tubing & wire harness to gas valve. Turn

on gas supply to heater and check for gas leaks, repair any gas leaks found.

Step 10. Restore 120 volt power supply to water heater and confirm proper operation following

the lighting instructions on the lighting instruction label or the lighting instruction located in the installation and operating instruction manual.

Step 11. Replace surround cover on top of

water heater.

Page 25

U.H.E Service Manual

Does blower

energize?

Is there 120VAC

across the white and

black wires at the

terminal block ?

(see photo at right)

Refer to ignition module/control board

illustration. Is there 120VAC between P5(1) and

P5(3)?

Page 25

Replace

ignition module/

control board.

Is there 120VAC

across the white and

black wires at the

terminal block ?

Refer to ignition module/ control board illustration.

Is there 120VAC between

P5(1) and P5(3)?

Determine

power

source

problem

and

correct

Check amp draw through

BLACK wire lead of blower

motor. Is there .6 to 3.0

amps?

Hot Surface Ignition

Models ONLY:

Refer to ignition

module, is there 24

VAC between P3(7)

and ground?

Thermostat not

calling for heat.

(see page 12)

Replace blower.

(see “Blower Replacement

Procedure”)

120VAC check at

Terminal Block

Black wire leading to blower motor looped

through amprobe.

Is Blower wheel secured to

blower motor shaft?

Hot Surface Ignition Models:

Are safety circuits in normal position?

Correct safety circuit problem per

safety circuit trace

(see page 27).

Call technical

support.

Replace ignition module/

control board.

Checking for 120VAC

(Black & White Wires)

Is there 120VAC

across the white and

black wires at the

blower?

(see photo at right)

Replace blower.

(see page 25)

Repair/replace

wire harness.

IGNITION MODULE

Page 26

LAARS Heating Systems

Blower Replacement Procedure

WARNING

Step 1. Position main power switch to “OFF”.

Step 2. Disconnect (unplug) water heater from

120 volt power source.

Step 3. Turn off gas supply to water heater.

Step 4. Un-latch & remove surround cover from top of

heater.

Step 5. Disconnect wire harness from blower.

Step 6. Disconnect intake vent and gas supply from gas valve assembly.

Step 7. Remove the 2 gas valve mounting screws (Torx bit) located at the

11:00 O-clock & 5:00 O-clock position on the venturi mounting flange.

Step 8. Remove The 4 blower flange mounting screws (5/32 Allen wrench) and remove blower

from transition flange.

Blower

Blower / gas valve

120 volt potential exposure. Isolate the

appliance and reconfirm power is

disconnected using a multi-meter.

gasket

Gas valve assembly

Blower flange

mounting screws

Blower / transition

gasket

Transition

flange

Step 12. Reconnect intake vent and

gas line to gas valve assembly and check for gas leaks repair any leaks found.

Step 13. Reconnect wire harness to blower assembly, restore 120 volt power supply & Gas supply

to water heater and confirm proper operation following the lighting instructions on the

lighting instruction label or the lighting instructions located in the installation and operating

instruction manual.

Step 14. Replace surround cover on top of

water heater.

Venturi

mounting flange

Venturi inlet

Step 9. Remove any residual gasket material

from venturi mounting flange and transition flange.

Step 10. Install new blower with new gasket

provided. Secure blower in place using screws from step 8.

Step 11. Reconnect gas valve assembly to blower

with new gasket provided. Secure gas valve in place using screws from step 7.

Gas valve

mounting screws

2 places.

Page 27

U.H.E Service Manual

Exhaust Pressure Switch Testing and Replacement

Sequence of operation:

The blocked vent pressure switch monitors the pressure in the exhaust tube. The switch contacts are normally closed and will not open unless there is a blockage in the exhaust venting or terminal (snow, ice, debris). If the blocked vent pressure switch contacts open after the thermostat initiates the blower, the blower will remain on for to 5 minutes waiting for the contacts to close. If the contacts remain open, the blower will stop and the PURGE LED will flash for hot surface ignition models.

WARNING

LED Status

Only power LED is on, or

Purge LED flashing.

Safety Circuit Trace

120 volt potential exposure. Use caution

making voltage checks to avoid personal injury.

Page 27

Does blower

energize?

Check PURGE LED status.

On within 5 minutes? Pressure switch is OK.

Flashing after 5 minutes?

Error code 29 again?

Call technical

support.

Does heater

function?

Verify proper

switch operation.

(see page 36)

Call for technical

wire leads of heater side

support.

Is there continuity

Through GREY

safety circuit harness?

(see photo below)

Depress reset button on vent

safety switch. Is

there continuity

across high limit

switch?

(see photo below)

Replace vent safety

switch.

(see page 37)

Is there continuity

through RED

wire leads of heater side

safety circuit harness?

(see photo below)

Check PURGE LED status

on ignition module,

Flashing after 45 seconds?

Control side

harness

Heater side

Safety Circuit OK,

(see page 36)

Replace exhaust

pressure switch (see

harness

page 29)

Check blower for proper

operation (see page 25)

Is blower OK?

Refer to

“Check Collector Pressure”

(see next page)

Correct blower problem

(see page 25)

Note: HOT SURFACE IGNITION MODELS ONLY - The blocked vent pressure switch

must be used with the revised ignition control,

identified with a yellow label.

Reset button

WARNING

Make sure exhaust collector compartment is not

overheating (350°F) before resetting vent safety

switch. If there is evidence the collector compartment

is overheating, CALL TECHNICAL SUPPORT.

Page 28

Exhaust Pressure Switch Testing and Replacement

Check Exhaust Tube Pressure

LAARS Heating Systems

With monometer, take a

reading at the exhaust

tube pressure tap location.

Is value negative (-) or

slightly postitive

(see illustration below).

With ohmmeter check

pressure switch for

continuity. Contacts should

be closed.

Is exhaust venting

system blocked or

obstructed? Also

check condensate

elbow and drain.

Is vent system total

length compliant with

vent tables in the

instruction manual?

blocked vent switch.

Clear obstruction.

Determine cause

and correct.

Reconfigure vent

system to be

compliant with

vent tables (see

Replace

(see page 29)

Is pressure in exhaust tube near 2.7" w.c. or more? If so, correct

blockage (above). If exhaust pressure is low (0.40" or less), replace

“Specifications”).

pressure switch.

Pressure switch O.K.

Exhaust Tube

pressure tap location

Exhaust tube

at bottom of heater

Page 29

U.H.E Service Manual

Exhaust Pressure Switch Testing and Replacement

Exhaust Pressure Switch Replacement Procedure

Step 1. Position main power switch to “OFF” position.

Step 2. Loosen adhesive backed rubber escutcheon from service panel access cover

and slide escutcheon back along exhaust pipe to allow for removal of cover.

Step 3. Remove screws from service panel access cover

(¼" nut driver) and remove cover from heater. (see photos at right)

Step 4. Disconnect silicone tubing and wire leads from

pressure switch. (see photos at right)

Page 29

Rubber

escutcheon

Step 5. Remove pressure switch mounting screws

(5/16" wrench) and remove pressure switch.

Step 6. Assemble new pressure switch to heater using

screws from step 5.

Step 7. Reconnect wire leads. Note: wire leads are

interchangeable with either terminal.

Step 8. Reconnect silicone tubing to pressure switch

as follows:

a) Exhaust pipe tubing connects to

single tap located on switch

Step 9. Restore 120 volt power supply to water heater

and confirm proper operation following the

lighting instructions on the lighting instruction label or the lighting instructions located in the installation

and operating instruction manual.

Step 10. Reinstall service panel access cover and

rubber escutcheon.

Pressure switch

mounting screw

5/16 hex head

Wire leads

Silicone tubing

Exhaust Tube

pressure tap location

Page 30

LAARS Heating Systems

Hot surface Igniter Testing Procedure

Is igniter resistance

less than 150 Ohms

(cold)? (see “check igniter resistance” below)

Replace

hot surface igniter

(see page 30)

Volt meter set to

OHM setting

Refer to ignition module illustration below,

is there 120VAC across terminals

P6(1) and P6(2)?

(Check during igniter warm up period,

indicated by the igniter LED glowing on the

ignition module).

Replace ignition module.

(see page 34)

WARNING

120 volt potential exposure. Use caution

making voltage checks to avoid

personal injury. Igniter may be too hot

to handle, take necessary precautions

Check harness

connection from igniter

to ignition module.

Meter probe

Hot surface

igniter

CHECK IGNITER

RESISTANCE

IGNITION MODULE

Page 31

U.H.E Service Manual

Hot surface Igniter Replacement Procedure

Page 31

Step 1. Position main power switch to “OFF”

Step 2. Disconnect (unplug) water heater

from 120 volt power source.

Step 3. Un-latch & remove surround cover

from top of heater.

Step 4. Fold back insulation in front of combustion assembly to expose hot surface igniter.

(see photo at right)

Step 5. Disconnect igniter wire leads from ignition module.

Step 6. Remove the 2 igniter mounting screws (magnetic

tip, long reach Phillips screw driver) and remove igniter and gasket from transition base flange.

Step 7. Remove any residual gasket material from

transition base flange.

120 volt potential exposure. Isolate the

appliance and reconfirm power is

disconnected using a multi-meter.

Note: New replacement igniter will not have a shield over element. Handle carefully to prevent breakage.

Note:

Do not handle igniter element

or allow foreign material to come in contact with element.

WARNING

Hot Surface

Igniter

Step 8. Install new igniter with new gasket provided using

screws from step 5. Arrange igniter flange with offcenter hole towards front of heater.

Off-center

mounting hole

Heater front

Step 9. Reconnect igniter wire harness.

Step 10. Fold insulation back into place. Be sure no wires are in contact with burner flange.

Step 11. Restore 120 volt power supply to water heater and confirm proper operation following the

lighting instructions on the lighting instruction label or the lighting instructions located in

the installation and operating instruction manual.

Step 12. Replace surround cover on top of

water heater.

Igniter mounting

screws

Transition

base flange

Igniter flange

Igniter gasket

Igniter filament

Page 32

Flame Sensor Testing Procedure

LAARS Heating Systems

WARNING

120 volt potential exposure. Use caution

making voltage checks to avoid

personal injury. Flame sensor may be

too hot to handle, take necessary

precautions

Refer to illustration below, is there

a minimum of 1 micro amp during

1.5 second flame proving period?

With flame sensor Disconnected

from ignition module, check

continuity to ground.

Is there continuity to ground?

Remove flame sensor from water heater.

Check continuity from tip of flame sensor

Is flame sensor free

flame sensor with emery

cloth. (see page 33)

to end of wire lead. Is there continuity?

of oxidation?

Clean or replace

Is ceramic of flame

sensor cracked?

Replace flame sensor.

(see page 33)

Refer to ignition module/control board

illustration.(24 volts should maintain beyond the

1.5 second flame proving period.)

Is there 24 volts AC at locations P3(2) & P3(5)?

Replace flame sensor with

gasket and/or wire lead.

(see page 33)

Volt meter set to

Call for

technical support

Flame sensing circuit OK

Micro amps setting

(µA)

Meter probe

Flame

sensor

terminal

Meter probe

Flame sensor

terminal on

ignition module.

Page 33

U.H.E Service Manual

Flame Sensor Replacement Procedure

Page 33

Step 1. Position main power switch to “OFF”

Step 2. Disconnect (unplug) water heater

from 120 volt power source.

Step 3. Un-latch & remove surround cover

from top of heater.

Step 4. Fold back insulation in front of combustion assembly to expose flame sensor.

(see photo at right)

Step 5. Disconnect wire lead from flame sensor.

Step 6. Remove the 2 sensor mounting screws (magnetic

tip, long reach Phillips screw driver) and remove flame sensor & gasket from transition base flange.

Step 7. Remove any residual gasket material from

transition base flange.

Step 8. Install new flame sensor with new gasket provided

using screws from step 6. Arrange flame sensor with hook towards burner.

Flame sensor

mounting screws

120 volt potential exposure. Isolate the

appliance and reconfirm power is

disconnected using a multi-meter.

Flame

sensor

WARNING

Flame sensor

gasket

Arrange hook

of sensor

towards burner

Step 9. Reconnect flame sensor wire.

Step 10. Fold insulation back into place. Be sure no wires are in

contact with burner flange.

Step 11. Restore 120 volt power supply to water heater and confirm proper operation following the

lighting instructions on the lighting instruction label or the lighting instructions located in

the installation and operating instruction manual.

Step 12. Replace surround cover on top of

water heater.

base flange

Transition

Page 34

LAARS Heating Systems

Ignition Module Replacement Procedure

Step 1. Position main power switch to “OFF”.

Step 2. Disconnect (Unplug) water heater

from 120 Volt power source.

Step 3. Un-latch & remove surround cover from top of water heater.

Step 4. Locate Ignition module on control panel inside surround area.

(see photo below)

Ignition Module

located on control panel

120 volt potential exposure. Isolate the

WARNING

appliance and reconfirm power is

disconnected using a multi-meter.

Note: Replacement hot surface

ignition module works on all UHE

models prior to and later than “CF”

serial numbers. Direct spark ignition

models use a different control board

(detailed in following section).

Step 5. Carefully disconnect all wire harness connection to ignition module. Connection are

non-interchangeable to insure proper reinstallation.

Step 6. Remove the 3 screws (Phillips screw driver) holding the ignition module in place and

remove ignition module from control panel.

Step 7. Install new ignition module and secure in place with screws from step 6.

Step 8. Carefully reconnect all wire harness connection to ignition module. Connection are

non-interchangeable to insure proper reinstallation.

Step 9. Restore 120 volt power supply to water heater and confirm proper operation following the

lighting instructions on the lighting instruction label or the lighting instruction located in

the installation and operating instruction manual.

Step 10. Replace surround cover on top of water heater.

Page 35

U.H.E Service Manual

Transformer Replacement Procedure

Page 35

Step 1. Position main power switch to “OFF”.

Step 2. Disconnect (Unplug) water heater

from 120 Volt power source.

Step 3. Un-latch & remove surround cover from

120 volt potential exposure. Isolate the

appliance and reconfirm power is

disconnected using a multi-meter.

WARNING

top of water heater.

Step 4. For Hot Surface Ignition models, refer to ignition module illustration below, Disconnect wire harness

P1 labeled “PRIMARY” and P2 labeled “SECONDARY” from ignition module.

Step 3

Disconnect harness

Step 5. Disconnect secondary leads (blue &

yellow wire) from thermostat board.

“P1” & “P2”

from ignition module

Note the blue wire is connected to 24 volt “HOT” terminal. (see photo below)

Disconnect blue & yellow wire from thermostat board. Note blue wire is

connected to 24 volt “HOT” terminal.

Step 5

Ignition module

Thermostat

board

Step 6. Remove the 2 screws ( short Phillips screw driver) holding the transformer in place and

remove transformer from control panel. (see photo below)

Step 7. Install new transformer and secure in

place with screws from step 6.

Step 6

Remove transformer

mounting screws

Step 8. Reconnect wire harness P1 & P2,

connections are non-interchangeable to insure proper reconnection.

Step 9. Reconnect blue & yellow wire leading from the

P2 connection on ignition module to thermostat board. Note the blue wire must connect to the 24 volt “HOT” terminal. (see photo at right)

Step 10. Restore 120 volt power supply to water heater and

confirm proper operation following the lighting instructions on the lighting instruction label or the lighting instruction located in the installation and operating instruction manual.

Step 11. Replace surround cover on top of water heater.

Thermostat

board

24 volt common,

yellow wire connection

24 volt Hot,

blue wire connection

Page 36

LAARS Heating Systems

Sequence of operation:

With the thermostat calling for heat, prior to energizing blower, the ignition module checks the vent safety switch for normal switch position of normally closed. If the vent safety switch contacts are open, (not in normal position), the ignition module waits indefinitely for contact to close, The vent safety switch must be manually reset to close the switch contacts.

WARNING

120 volt potential exposure. Use caution

making voltage checks to avoid personal injury.

Heater side

harness

Locate harness

connection.

(see photo at right)

Is there continuity

Through GREY

Lead wires of heater side

harness?

(see photo at right)

Control side

harness

Reset button

Call technical

support.

Does heater

function?

Depress reset

button on high

limit switch. Is

there continuity

across high limit

switch?

(see photo below)

Replace vent

safety switch

(see page 37)

Reset heater, observe

heating cycle. Does

switch open?

Does switch open prior

to 350°F?

Replace vent safety

switch

(see page 37)

Is temp over 350°F?

DO NOT OPERATE

System over heating,

immediately contact

System OK

HEATER

technical support.

WARNING

Make sure exhaust collector compartment is not

overheating (350°F) before resetting vent safety

switch. If there is evidence the collector compartment

is overheating, CALL TECHNICAL SUPPORT.

Page 37

U.H.E Service Manual

Vent Safety Switch Replacement Procedure

Step 1. Position main power switch to “OFF”.

Step 2. Loosen adhesive backed rubber escutcheon from service panel access cover

and slide escutcheon back along exhaust pipe to allow for removal of cover (see photos at right).

Step 3. Remove screws from service panel access cover

(¼" nut driver) and remove cover from heater (see photos at right)

Page 37

Rubber

escutcheon

Step 4. Disconnect wire leads from vent

safety switch (see photo at right).

Step 5. Remove the 2 switch mounting

screws (Phillips screw driver) and nuts (5/16 wrench) and remove switch from heater.

Step 6. Install new switch using screws

from step 5.

Step 7. Reconnect wire leads.

Note: wire leads are interchangeable with either switch terminal.

Vent safety

switch

Step 8. Restore 120 volt power supply to water heater and confirm proper operation following the lighting

instructions on the lighting instruction label or the lighting instruction located in the installation and

operating instruction manual.

Step 9. Reinstall service panel access cover and

rubber escutcheon.

Page 38

LAARS Heating Systems

Disassembly Procedure for Access to Anodes & Flue Baffles

WARNING

Heater components may be HOT when performing the following steps in this procedure.

Take necessary precaution to prevent personal injury.

Step 1. Position main power switch to “OFF”.

Step 2. Disconnect (Unplug) water heater

from 120 Volt power source.

Step 3. Un-latch & remove surround cover from top of heater.

Step 4. Disconnect wire harnesses to allow for removal of control panel.

Note: Where ever possible, rather than disconnecting at the control panel, follow wire harness away from control panel and disconnect at control component location.

Step 5. Remove the three control panel mounting screws (¼” nut driver) and remove control

panel from the water heater (see photos below).

Control Panel

Mounting Screw

Step 6. Completely remove insulation (two pieces) from top of heater to expose collector cover

120 volt potential exposure. Isolate the

appliance and reconfirm power is

disconnected using a multi-meter.

WARNING

Remove Control

Panel

Step 7. Remove all collector cover

screws (5/16" socket) and remove collector cover (see photos at right).

Collector

cover

Step 8. Photo 44 shows heater with collector cover removed allowing

access to anode rods and flue baffles.

a) for anode service, see page 39. b) for flue baffle service, see page 40. c) for powered anode service, see page 41.

Note: UHE100T399 models have only 1 anode rod under the 2ndpass collector cover.

Anode

locations

Flue

baffles

Page 39

U.H.E Service Manual

Anode inspection and replacement

WARNING

Heater components and stored water may be HOT when performing the following steps in

this procedure. Take necessary precaution to prevent personal injury.

Step 1. Turn off water supply and drain water heater.

Step 2. Disassemble water heater per “Disassembly Procedure for Access to Andoes & Flue Baffles”.

Step 3. Locate and remove anode rods from heater (1-1/16 hex socket).

Step 4. Visually inspect anode rod. Anode rod should show signs of depletion, this is normal. If

the depletion is ½ of the original diameter (approximately ¾" diameter), replacement is recommended. If any of the steel core of the anode is exposed, replacement is recommended.

Page 39

Step 5. Upon completion of inspection or subsequent replacement, apply thread sealing tape or other

thread compound to threads of anode and reinstall into heater. Restore water supply and check for and repair any leaks found.

Step 6. Reinstall collector cover per “Collector Cover Installation Procedure”.

Step 7. Reinstall collector insulation and control panel, reconnect control panel wire harnesses.

Step 8. Restore 120 volts to water heater and verify proper heater operation following the

instructions on the lighting instruction label or the lighting instruction located in the

installation and operating instruction manual.

Step 9. Replace surround cover on top of water heater.

Page 40

LAARS Heating Systems

Flue baffle inspection and replacement

WARNING

Heater components may be HOT when performing the following steps in this procedure.

Take necessary precaution to prevent personal injury.

Step 1. Disassemble heater per “Disassembly Procedure for Access to Anodes & Flue Baffles”.

Step 2. Remove flue baffles from heater (pliers) (8 two inch baffles & 2 four inch baffles).

Step 3. Visually inspect flue baffles. Flue baffles should show signs of oxidation, this is normal.

If the oxidation has deteriorated any portion of the flue baffle, replacement is recommended. If any restrictors are missing, replacement is recommended.

Step 4. Upon completion of inspection or subsequent replacement, reinstall flue baffles into

heater.

Step 5. Reinstall collector cover per “Collector Cover Installation Procedure” see page 42.

Step 6. Reinstall collector insulation and control panel, reconnect control panel wire harnesses.

Step 7. Restore 120 volts to water heater and verify proper heater operation following the

instructions on the lighting instruction label or the lighting instruction located in the

installation and operating instruction manual.

Step 8. Replace surround cover on top of water heater.

Page 41

U.H.E Service Manual

Powered Anode Replacement for UHE100T399 only

Powered Anode Replacement UHE100T399 models only

WARNING

Heater components may be HOT when performing the following steps in this procedure.

Take necessary precaution to prevent personal injury.

The powered anode control module is located on the right vertical side of the control panel inside the surround panel. The control has a LED indicator light to show the status of operation. When the tank is filled with water and the power supply is on to the water heater, the light should have a steady green glow to indicate that protection current is flowing and operating normally. If the indicator light is not glowing, the power supply to the water heater or powered anode system is disconnected.

Page 41

Step 1. Check the power supply or wire connections to the powered anode control.

Step 2. Indicator light diagnostic codes:

a) If the control is flashing red, then there is a malfunction with the powered anode system.

Make sure there are no bare spots in the wire insulation to the powered anode rods.

Step 3. Check all electrical connections. The powered anode rods are insulated from the

water heater tank in the bushing.

a) With an ohmeter, check continuity between the powered anode terminal and the

bushing. There should not be continuity. If there is continuity, replace the powered anode assembly.

Volt meter set

to OHM setting

Page 42

LAARS Heating Systems

Collector Cover Installation Procedure

Step 1. Remove old silicone from top surface of collector flange and collector cover.

Step 2. Apply ¼" bead of Ultra Copper Silicone around entire collector flange surface. Allow

caulk to “cure” for 10 minutes.

Step 3. Carefully reinstall collector cover, tighten screws evenly.

Step 4. Allow a minimum of 6 hours before putting heater back in service.

Apply ¼" bead of Ultra Copper

Silicone around entire collector

flange surface

Page 43

U.H.E Service Manual

Product Handling - Carefully uncrate the heater. Move in place with a hand truck (Do not use the venting pipes for handles).

Electrical Requirements - Make sure there is 120 volts line voltage. Line voltage must be properly polarized. Adequate ground supplied to the heater.

Venting Requirements - All venting must stay within the required lengths and diameter (see table below). Proper support of the venting pipe is a MUST (every 5ft vertical and 3ft horizontal). Termination must be located to prevent re-circulation of flue gases. Medium to long sweep 90° elbows or straight exhaust terminal coupling recommended.

Gas Requirements - Gas piping sized adequately, ¾" or larger to heater or 1" or larger for UHE100T399 models. Install a properly sized regulator (if unknown, assure an adequate volume of gas is available). 7" W.C. is required when the unit is running. Gas pressure must stay below 14" W.C. static pressure. Pressure drops between static pressure and operating flow should be less than 3" W.C.

Page 43

Condensate Requirements - Condensate line needs to slope to a drain at a minimum of ¼" per foot. Make sure the condensate line does not have the potential to freeze. If using more than one heater and using a common condensate line, make sure the condensate line is properly sized.

Service/Mechanical Room - Provide adequate space for servicing heater. Leave room to get to the top and bottom pressure switches as well as enough overhead room to remove the anode rods for servicing (18" min.).

Vent tables

Balanced Direct Vent Systems

PVC, CPVC

Total length of intake piping and exhaust piping

added together must not exceed “Maximum

Combined Length” Shown below

Maximum Combined Length (feet)

Model Number 3"

UHE60T125, UHE100T150 120'

UHE60T150, UHE100T199

UHE60T199 80' 130'

UHE100T250

100'

80'

170'

150'

130'

Total length of exhaust piping must not exceed

Model Number 3"

UHE60T125, UHE100T150 120'

UHE60T150, UHE100T199

Power Vented Systems

PVC, CPVC

“Maximum Vent Length”

Shown below

Maximum Vent Length (feet)

170'

100'

UHE60T199

UHE100T250 80' 130'

80'

150'

130'

UHE100T300

UHE100T399 50' 100'

Unbalanced Direct Vent Systems

Air intake CAN NOT exceed exhaust

by more than 30 feet

Note: each 3" & 4" 90° Elbow is equivalent to 5 feet of straight pipe. Note: each 3" & 4" 45° Elbow is equivalent to 2.5 feet of straight pipe.

60'

110'

UHE100T300

UHE100T399 50' 100'

60'

110'

Page 44

Date

LAARS Heating Systems

Service Provider

Phone Number

Venting (PVC, CPVC):

Vent size 3" or 4"

Intake 90's (qty)

Exhaust 90's (qty)

Gas Line:

Size & material

Distance from meter to water heater

Electrical:

Line Voltage

Intake 45's (qty)

Exhaust 45's (qty)

Gas Pressure:

Static

Running Inlet

Manifold

Low Voltage

Model Number

Serial Number

Length of straight pipe (intake)

Length of straight pipe (exhaust)

Venturi:

Setting from Bottom in Turns

Polarity

Igniter Resistance:

LED Flashing Y or N Which One(s)

Error Codes on Control Display (Direct Spark Ignition System Only): __________________________________

Condensate Line:

Size & Material

Length

Is trap provided Y or N

Combustion:

CO2 CO

Installation Site Name & Address:

Flame Sense Micro -Amps:

Installation Site Contact Name & Phone

Spark Gap: ___________

Exhaust Collector Pressure:

Positive Inches W.C.

Number

Page 45

U.H.E Service Manual

Page 45

1 Combustion Surround Assy.

2 Burner Assy (specify model)

3 2ndPass Top Collector Cover

4 Screw 10-16 x 3/4

5 Vent Termination Elbow

6 Thermostat Sensor Probe

7 Baffle 4" Flue (specify model)

8a Anode Rod Assy

8b Powered Anode (for UHE100T399)

9 Baffle 2" Flue

10 Wire Harness Service Panel

11 Plastisert Nipple 1-½" NPT

12 Plug

13 Nipple

14 T&P Relief Valve

Exhaust Pipe (PVC) w/Hose Barb

(except UHE100T399) 16 Condensate Trap Elbow (specify model)

17 Silicone Hose

18 Outer Door Service Panel (specify model)

Vent Pipe Support Bracket (except 19

UHE100T399) 20 NSF Escutcheon

21 Exhaust Pressure Switch

22 Nuts

23 Collector Temperature Limit Switch

24 Screw 6-32x 3/8

25 Cleanout Access Cover

26 Cleanout Gasket

27 Screw 5/16-18 x ¾ HH Grade 5

28 Cleanout Cover

29 Cold Water Inlet (Hydrojet) Assy.

30 No Handle Brass Drain Valve

31 Concentric Vent System (optional)

32 ASSE Approved Mixing Valve (optional)

Customer must specify complete model

number and serial number when

ordering service parts.

Page 46

AA Latch Assy

BB Screw 8-32 x ½ RHCR

CC Ignition Control Assy

DD Jacket Head

EE Main Power Switch

FF Potentiometer

GG Combustion Surround

JJ Surround Base

Customer must specify complete model

number and serial number when

ordering service parts.

LAARS Heating Systems

1A Combustion Surround Assy. (specify model)

2A Blower Gas Valve Assy (specify model)

3A Burner Assy (specify model)

4A Blower EBM (specify model)

5A Silicone Hose

6A Burner Mounting Insert Gasket

7A Screw 10-32 x3/4

8A Gasket & Screw

9A Gas Valve (specify model)

10A Nipple (specify model)

11A Reducer (specify model)

12A Nipple (specify model)

13A 2" dia. Flex Reducer (or PVC reducer for 399)

14A Inlet (PVC)

15A Gasket Blower Transition (specify model)

16A Screw 8-32 x ¼ RHCR

17A Gasket Flame Sensor

18A Flame Sensor

19A Transition Tube

20A Nut Hex Washer

21A Gasket Hot Surface Igniter

22A Hot Surface Igniter

23A Burner Mounting Gasket

24A Burner Tube

25A Burner Mounting Gasket

26A Burner Mounting Insert

Page 47

U.H.E Service Manual

Page 47

Electronic Control Module

Screw 8-32 x 1/2

Control Mounting Panel

Thermostat PC Board

Transformer 120VAC x 24VAC x 40VA

Terminal

Terminal Strip

Power Cord

Control Wire Harness

Thermostat Wire Harness

10C

Rectifier Harness (specify model)

11C

Blower Wire Harness (specify model)

12C

Power Switch Wire Harness

13C

Flame Sensor Wire Harness

14C

Powered Anode Control Harness (399 only)

15C

Powered Anode Harness (399 only)

16C

Powered Anode Control (399 only)

17C

Customer must specify complete model

number and serial number when

ordering service parts.

Page 48

LAARS Heating Systems

AC Alternating Current BTU/H British Thermal Units CO Carbon Monoxide CO2 Carbon Dioxide DC Direct Current DSI Direct Spark Ignition ECO Energy Cut Off GFI Ground fault interrupt

GPM Gallons per Minute

HSI Hot Surface Igniter

Hz Hertz LED Light Emitting Diode

NOx Oxides of Nitrogen

NPT National Pipe Thread

PSI Pounds per Square Inch

RPM Revolutions per Minute VA Volt Amps

VAC Volts Alternating Current W.C. Inches of Water Column °C Degrees Centigrade °F Degrees Fahrenheit

µA Micro Amp

NOTES

800.900.9276 • Fax 800.559.1583 (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