VT8800/WT8800 WATER HEATER CONTROLS
9
69-1731
Fig. 8. Troubleshooting Without Status Light.
Thermopile Output Check.
1.
Turn device knob to OFF.
2.
Disconnect thermopile leads.
3.
Turn device knob to PILOT, hold down knob to light
pilot burner. Hold the knob down for five or more
minutes.
4.
After five minutes, check thermopile output by
connecting the voltmeter to the positive red lead
and negative white leads.
5.
Output should be at least 350 mV. (See Fig. 8.)
Connect the 3.6 ohm resistor between the two ther-
mopile leads, the voltage should be at or higher
than one half of the open circuit voltage.
6.
The terminals prevent miswiring of positive (1/4 in.)
and negative (3/16 in.) leadwires.
7.
Flame must envelop thermopile at Hot Junction
(3/8 in. below tip).
8.
Keep heat away from cold junction (brass sleeve)
for maximum output.
Fig. 9. Thermopile output.
Sensor Calibration Check
1.
Turn device knob to OFF.
2.
Disconnect sensor leads (1 x 4 connector).
3.
Use ohmmeter to check resistance on upper or
lower sensor (see wiring diagram).
4.
Typical resistance values will be between 1700
ohms (160°F tank temperature) and 9300 ohms
(80°F tank temperature).
5.
Replace sensor assembly if you measure open
circuit or the ohms reading is significantly out of
range.
INSTRUCTIONS TO THE
HOMEOWNER
WARNING
Fire or Explosion Hazard.
Can cause severe injury, death or property
damage.
1.
IF YOU SMELL GAS:
• Turn off the gas supply at the appliance
service valve. On LP systems, turn off the
gas supply at the gas tank.
• Do not light any appliances in the house.
• Do not touch electrical switches or use the
phone. Leave the building and use a
neighbor’s phone to call your gas supplier.
• If you cannot reach your gas supplier, call
the fire department.
2.
The water heater control must be replaced in
event of any physical damage, tampering, bent
terminals, missing or broken parts, stripped
threads or evidence of exposure to heat.
TURN DEVICE KNOB FROM OFF TO
PILOT, PRESS DOWN KNOB AND HOLD,
LIGHT PILOT BY DEPRESSING PIEZO
IGNITION BUTTON, PILOT SHOULD
LIGHT
CHECK:
• WIRING OF THERMOPILE LEADS
• FLAME COVERAGE OF THERMOPILE
• THERMOPILE OUTPUT IS TOO LOW-RUN
•
THERMOPILE OUTPUT CHECK
STATUS LIGHT SHOULD FLASH AFTER
1 MINUTE, LED WILL FLASH NORMAL
SINGLE BLINK, RELEASE THE DEVICE
KNOB, PILOT SHOULD REMAIN LIT
TURN DEVICE KNOB TO DESIRED
TEMPERATURE SETTING, BURNER WILL
TURN ON ONLY IN ACTIVE CALL FOR
HEAT (WATER TEMPERATURE IS LESS
THAN TEMPERATURE SETTING MINUS
DIFFERENTIAL)
SYSTEM OK
CHECK:
• EXCESSIVE INLET PRESSURE
• TANK TEMPERATURE IS AT OR CLOSE
TO SET POINT.
• RUN SENSOR CALIBRATION CHECK
NO
NO
NO
YES
YES
YES
M22536C
TROUBLESHOOTING GUIDE WITHOUT STATUS LIGHT
CHECK:
• INLET PRESSURE
• MAKE SURE AIR IS BLED OUT OF SYSTEM
• PIEZO SPARKING TO THERMOPILE
• CLOGGED PILOT ORIFICE
• GAS LEAK IN PILOT TUBING CONNECTIONS
M22535B
TIME (MINUTES)
OUTPUT (mV)
THERMOPILE OUTPUT WITH TIME
500
600
400
300
200
100
0
0
1
2
3
4
5
6
7
8
9
10
900
800
700
NORMAL RANGE
OUTPUT TOO LOW
69-1731.fm Page 9 Monday, October 10, 2005 11:02 AM