John Wood Superflue Power Vent (75 Gallon) - Manual (Page 23)

Gas Control/Thermostat
This heater may be equipped with a Robertshaw WDER
2000N gas control/thermostat and a hot-surface igniter. This
control is a combination gas valve, thermostat and ignition
controller for use on this power vented water heater. The
valve contains a micro-controller that supervises the ignition
sequence and monitors the temperature settings and oper-
ation of the heater.
This heater is equipped with a hot-surface ignition sys-
tem that automatically ignites the burner. Do not
attempt to light this heater manually with a match or
flame-producing device.
Putting the Heater into Service
1. Turn the manual gas shut-off valve for the heater to the
“ON” position.
2. Turn the gas control switch to “ON”.
3. Follow the Lighting Instructions (Robertshaw) given on
the side of the water heater and also depicted in this
manual. See also “Gas Supply”, “Water Heater
Operation” and “Sequence of Operation”.
Temperature Adjustment
The temperature dial is adjusted to its lowest tempera-
ture position when shipped from factory.
• The temperature of the water can be selected by adjust-
ing the temperature dial located on the front of the con-
trol (see Figure 20).
• The large arrow position of the thermostat is the pre-
ferred starting point.
• Each division on the thermostat dial represents a 3°C
(5°F) water temperature change.
Note: To avoid scald injury, set the control to the lowest set-
ting that will supply your hot-water needs.
There is a hot-water scald potential if the thermostat is set
too high. In households with children, disabled or the elder-
ly, select a lower temperature setting. Tempering valves
(mixing valves) for reducing point-of-use water tempera-
tures are available and may be required by your local
authority. Consult a licensed plumber or your local plumbing
authority.
Heater Shutdown
1. Turn the thermostat dial to the lowest setting.
2. If the heater is running let it shut down first.
3. Turn off all electrical power to the heater or unplug the
power cord from the receptacle.
4. a) For WDER 2000N controls, press the gas control
switch located on the top of the control. It will auto-
matically turn to the “OFF” position.
5. Turn the manual gas supply valve to the water heater to
the “OFF” position.
Water Heater Operation
Figure 22 shows the water heater's sequence of operation
when a call for heat is initiated. The ignition control module
will attempt to light the burner three times. If the ignition con-
trol does not detect ignition it will enter lockout mode and
flash the error code.
– 23 –
CAUTION:
Read before proceeding. If you do not follow
these instructions exactly, a fire or explosion
may result, causing property damage, per-
sonal injury or loss of life.
WARNING
Risk of scalding
Hot water can produce third degree burns
in 6 seconds at . . . . . . . .60°C (140°F)
in 30 seconds at . . . . . . .54°C (130°F)
in 5 minutes at . . . . . . . . .49°C (120°F)
CONTROL CHECKS TO
ENSURE PRESSURE
SWITCH IS OPEN
BLOWER IS
ENERGIZED
CONTROL CHECKS TO
ENSURE PRESSURE
SWITCH CLOSES
INDICATING BLOWER
IS OPERATING AND
THERE ARE NO
VENTING BLOCKAGES
(INLET OR OUTLET)
IGNITER IS
ENERGIZED AND MAIN
VALVE IS OPENED
MAIN BURNER ON AND
THE FLAME IS
SENSED BY CONTROL
MAIN BURNER
CONTINUES TILL THE
WATER IN THE TANK
REACHES
THERMOSTAT
SETTING
MAIN BURNER SHUTS
OFF. BLOWER
CONTINUES FOR A
POST PURGE TIME
CALL FOR
HEAT
Figure 22 Sequence Of Operation