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WARNING:

  If the information in these instructions is 

not followed exactly, a fire or explosion may result 
causing property damage, personal injury, or death.

WHAT TO DO IF YOU SMELL GAS

   Do not try to light any appliance.

x

Do not touch any electrical switch; do not use any

      phone in your building.

x

Immediately call your gas supplier from a neighbor's phone.  

Follow the gas supplier's instructions.

x

If you cannot reach your gas supplier, call the fire

department.

Installation and service must be performed by a qualified
installer, service agency or the gas supplier.

FOR YOUR SAFETY

   Do not store or use gasoline or other flammable, 

combustible, or corrosive vapors and liquids in the 
vicinity of this or any other appliance.

CAUTION

Incorrect operation of this appliance may 
create a hazard to life and property and 
will nullify the warranty.

DANGER

Do not store or use gasoline or other 
flammable, combustible, or corrosive 
vapors and liquids in the vicinity of this 
or any other appliance.

IMPORTANT

B

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 pr

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, p

lease

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w

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an

d i

ts

 c

o

mp

onents

 

fo

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oss

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ble

 d

a

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age

.  

DO NOT

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r wi

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onents

.  

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 p

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 p

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.

WARNING

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 pr

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a

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To

 

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UNDER NO CIRCUMSTANCES MUST FLAMMABLE 
MATERIALS, SUCH AS GASOLINE OR PAINT THINNER BE 
USED OR STORED IN THE VICINITY OF THIS WATER 
HEATER, VENT-AIR INTAKE SYSTEM OR IN ANY 
LOCATION FROM WHICH FUMES COULD REACH THE 
WATER HEATER OR VENT-AIR INTAKE SYSTEM.

WARNING

DO NOT ATTEMPT TO LIGHT ANY GAS APPLIANCE IF YOU 
ARE NOT CERTAIN OF THE FOLLOWING:

x

Liquefied petroleum gases/propane gas and natural gas 
have an odorant added by the gas supplier that aids in 
the detection of the gas.

x

Most people recognize this odor as a “sulfur” or “rotten 
egg” smell.

x

Other conditions, such as “odorant fade” can cause the 
odorant to diminish in intensity, or ”fade”, and not be 
as readily detectable.

x

If you have a diminished sense of smell, or are in any 
way unsure of the presence of gas, immediately contact 
your gas supplier from a neighbor's telephone.

Gas detectors are available. Contact your gas supplier, or 
plumbing professional, for more information.

CAUTION

I

f

 

s

w

eat

 

f

i

tt

i

ngs

 

a

r

e

 

to

 

be

 u

se

DO NOT

 

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eat

 

to

 

t

h

e

 

n

ipp

les

 

on

 

to

of

 

t

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 w

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r.  Sw

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t

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t

u

b

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to

 

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a

d

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p

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d

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to

 

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 w

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c

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c

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ons

.  I

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at

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 h

eat

 i

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not

 

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to

 

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ipp

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 c

onta

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n

i

ng

 

a

 p

last

ic 

l

i

ne

r.

WARNING

FAILURE TO INSTALL AND MAINTAIN A NEW, LISTED 3/4” X 
3/4” TEMPERATURE AND PRESSURE RELIEF VALVE WILL 
RELEASE THE MANUFACTURER FROM ANY CLAIM THAT 
MIGHT RESULT FROM EXCESSIVE TEMPERATURE AND 
PRESSURES.

WARNING

Hydr

ogen

 

gas

 c

an

 

be

 pr

o

duc

e

d i

n

 

an

 

o

p

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r

at

i

ng

 w

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h

eate

t

h

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 h

as

 

not

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d w

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a

w

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f

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tan

fo

a

 

long

 p

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ri

o

of

 

t

im

e

 (

gene

r

all

t

w

o

 w

ee

k

s

 

o

r m

o

r

e

).  

Hydr

ogen

 

gas

 i

s

 

e

x

t

r

e

m

el

fla

mm

able

.  

To

 pr

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v

ent

 

t

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p

oss

i

b

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of

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 c

on

di

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, w

e

 

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c

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mm

en

t

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 h

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et

 

to

 

be

 

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p

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fo

se

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al

 

mi

n

u

tes

 

at

 

t

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 ki

t

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en

 

s

i

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befo

r

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se

 

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c

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al

 

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 which i

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m.  I

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 pr

esent

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 wi

ll

 

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an

 u

n

u

s

u

al

 

so

u

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s

uch 

as

 

a

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ng

 

t

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t

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e

 pip

es

 

as

 h

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 w

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beg

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ns

 

to

 

flo

w.  D

o

 

not

 

s

m

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k

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a

v

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o

p

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fla

m

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t

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fa

uc

et

 

at

 

t

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t

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e

 i

t

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s

 

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p

en

.

CAUTION

T

ur

n

 

off

 

o

r di

s

c

onne

c

t

 

t

h

e

 

ele

c

t

ric

al

 p

o

w

e

s

upp

l

to

 

t

h

e

 

w

ate

r h

eate

befo

r

e

 

se

rvici

ng

. L

abel

 

all

 wir

es

 pri

o

to

 

di

s

c

onne

c

t

i

on

 wh

en

 

se

rvici

ng

 c

ont

r

ols

.   Wiri

ng

 

e

rr

o

r

s

 c

an

 

c

a

u

se

 impr

o

p

e

an

d d

ange

r

o

u

s

 

o

p

e

r

at

i

on

.  V

e

ri

f

y pr

o

p

e

o

p

e

r

at

i

on

 

afte

se

rvici

ng

.

P

age

 3

3

Summary of Contents for U2TW75T*RN

Page 1: ...238 50629 00A SERVICE MANUAL Troubleshooting Guide and Instructions for Service To be performed ONLY by qualified service providers Models Covered by This Manual U2TW75T RN UTW475S76R N Denotes Warra...

Page 2: ...I Pilot Testing Cleaning and Replacement 19 III Pressure Switch Testing and Replacement 20 IV Blower Testing and Replacement 22 V Blower Temperature Switch Testing and Replacement 24 VI Gas Control Te...

Page 3: ...O NOT ATTEMPT TO LIGHT ANY GAS APPLIANCE IF YOU ARE NOT CERTAIN OF THE FOLLOWING x Liquefied petroleum gases propane gas and natural gas have an odorant added by the gas supplier that aids in the dete...

Page 4: ...d exterior environments Cooler operation increases blower life by reducing bearing wear and noise Rugged Wiring Connections receptacle type connections promote error free wiring Increased Vent Lengths...

Page 5: ...ual Page 5 Manometer A liquid U tube type or a digital type can be used This device is used to measure gas and or air pressure and vacuum Multi Meter A digital type is strongly recommended This device...

Page 6: ...rease 1 28 opens on vacuum decrease 1 25 Power supply Dedicated 115VAC 60 Hz 15A Approved Gas Type Natural Venting System Power vent through the wall or vertical through the roof Approved Vent Materia...

Page 7: ...th ft m 4 Diameter 10 2 cm PVC Vent Connector Lengths 1 175 53 3 10 3 1 Through the Wall 2 170 51 8 10 3 1 Through the Wall 3 165 50 3 10 3 1 Through the Wall 4 160 48 8 10 3 1 Through the Roof 0 50 1...

Page 8: ...um Post purge 15 Seconds PS Fault Delay failed open close Retry after 2 Minutes Soft Lockout Retry after 5 Minutes ECO Limit Lockout Indefinite cycle power to restart Simulated Resistive Load Lockout...

Page 9: ...operation with no perceivable delay If the device is out of range the control LED immediately flashes 7 times with 3 second pause Normal Heating Sequence 1 2 Blower Energizes 3 Pressure Switch Proves...

Page 10: ...eds to verify resistive delay for 2 minutes and flashes 8 times then once with a three second pause This process is repeated 5 times until the control either returns to normal operation or proceeds to...

Page 11: ...ed the gas control turns off the blower and flashes 6 times then 2 times with 3 second pause The gas control waits 5 minutes before repeating ignition sequence 4 Trial For Ignition Fault a Pressure sw...

Page 12: ...build up on pilot electrode 4 Wire damage to pilot assembly or bad connection at gas valve 1 4 Page 19 1 Pressure switch tubing kinked or blocked 2 Blocked pressure tap on switch or blower 3 Faulty p...

Page 13: ...o be reset 2 Control is wet or physically damaged 1 Interrupt power supply 2 Replace gas control page 26 Troubleshooting Six three flash three second pause Pilot flame extinguished System auto resets...

Page 14: ...rk igniter flame sensor wire and the simulated resistive device from the gas control see photo 1 b Disconnect main burner feed line wrench pilot tube 7 16 wrench and igniter wire from gas control see...

Page 15: ...O NOT OVER TIGHTEN SCREWS Inner Door Gasket Replacement Procedure WARNING If the information in these instructions is not followed exactly a fire or explosion may result causing property damage person...

Page 16: ...on chamber Step 13 Reconnect spark igniter flame sensor wire and simulated resistive device to the gas control See photos 1 2 on page 14 Step 14 Reconnect the pilot tube to the gas control and tighten...

Page 17: ...dure below DANGER Under no circumstances shall flammable materials be used or stored in the vicinity of the water heater If flammable vapors are present a fire or explosion may result causing property...

Page 18: ...CE PROCEDURE I steps 5 through 16 Step 11 To resume operation follow the instructions located on the lighting instruction label or the lighting instructions located in the installation and operation m...

Page 19: ...acks in the pilot tube If found the pilot must be replaced Step 7 Inspect pilot orifice a Remove 7 16 nut from bottom of pilot assembly b Remove pilot tube and pilot orifice c inspect pilot orifice fo...

Page 20: ...blockage Replace switch see page 21 Position gas valve power switch to the ON position and adjust thermostat to call for heat this will start the blower Check with multi meter do pressure switch conta...

Page 21: ...p 1 Position gas control power switch to the OFF position Step 2 Remove the three screws Phillips screw driver from control access cover on blower assembly and remove cover see photos 4 and 5 Pressure...

Page 22: ...C Step 1 Position gas control power switch to ON position and adjust control to call for heat Step 2 Remove the three screws Phillips Screw driver from control access cover on blower assembly and rem...

Page 23: ...et head of water heater Step 8 Set new blower with gasket in place using locating pins on blower flange to line up with location holes in jacket head Be sure not to damage gasket Step 9 Secure blower...

Page 24: ...driver from control access cover on blower and remove cover see photos 17 and 18 Step 3 Locate blower temperature switch see photo 19 Reconnect wire leads and observe heater operation Do exhaust gas...

Page 25: ...llow wire leads from switch Step 5 With an appropriate tool such as side cutters snip the retaining lug from the blower housing to allow removal of temperature switch see photo 18 Step 6 Remove switch...

Page 26: ...or damage to the gas control may occur If necessary use a length of NPT pipe threaded into gas inlet of gas control b Position the main burner feedline and pilot tube back to the gas control and atta...

Page 27: ...ctions located on the lighting instruction label or the lighting instructions located in the installation and operation manual Step 7 If gas pressure is outside the specification noted above refer to...

Page 28: ...and 45 000 ohms If outside of this range replace the simulated resistive device If there is no continuity test the resettable thermal switch by following SERVICE PROCEDURE IX If the resettable therma...

Page 29: ...uity is not indicated the switch is open possibly due to an over heating condition The switch is designed to open at predetermined temperatures An open switch can be reset by depressing the red colore...

Page 30: ...hermal switch into place using screws from step 6 DO NOT OVER TIGHTEN SCREWS Step 8 Place manifold cover back in position and secure using the screws from step 4 Step 9 Reconnect wire leads from gas c...

Page 31: ...the igniter sparking Y Y Is LED on gas valve flashing the heartbeat code alternating bright dim N Safety circuit voltage is OK No voltage from gas control call for technical support Y NOTE This proced...

Page 32: ...meter set to volts AC is there 115VAC across terminals shown in photo 28 N Y 27 28 Reconnect cord set shown in photo 27 Repair damage Check for damage to AC supply power cord Y N Replace Blower 31 Che...

Page 33: ...be Inlet nipple dip tube should be free of cracks and any blockage Hydro jet slots should be open and free of any blockage Any damage such as cracks restriction due to deformation or unintentional hol...

Page 34: ...spect outlet nipple anode Outlet nipple anode should show signs of depletion this is normal If depletion is of the original anode diameter approximately diameter replacement is recommended If any of t...

Page 35: ...ary Step 8 Reinstall baffle into flue tube Be sure baffle hanger tab are inserted into notch location at the top of the flue tube see photos 35 36 Step 9 Check Burner to insure no scale has accumulate...

Page 36: ...ute Hz Hertz KWh Kilowatt hour LED Light Emitting Diode NPT National Pipe Thread Ohms Ohms resistance PSI Pounds per Square Inch RPM Revolutions per Minute ECO Energy Cut Out VAC Volts Alternating Cur...

Page 37: ...NOTES Page 3 37...

Page 38: ...NOTES Page 38 38...

Page 39: ...r 10 Gas Control 11 Gas Control Wire Harness 12 Brass Drain Valve 13 Ultra Low NOx Burner 14 Right Side Inner Door Assembly 15 Pilot Assembly 16 Manifold Mount Hex Head Screw 17 Manifold Mount 18 Main...

Page 40: ......

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