WV4460E POWER VENT WATER HEATER CONTROLS
69-1872EF—01
8
4.
Dusty, wet, or corrosive environment. Since these
environments can cause the control to deteriorate
more rapidly, the system should be checked more
often.
The system should be replaced if:
a. It does not perform properly on checkout or
troubleshooting.
b. The control is likely to have operated for more
than 100,000 cycles.
c. The control has been flooded.
SERVICE
WARNING
Fire or Explosion Hazard
Can cause severe injury, death, or property
damage.
Do not disassemble the water heater control; it
contains no replaceable components. Attempted
disassembly or repair can damage the control.
Sequence of Operations
1.
Follow the sequence of operation as shown in
Table 4. WV4460E Sequence of Operation.
Sequence
Mode
Description
Power Up
1
Start-up
Upon Power up, the control runs a safe-start check of
RAM, ROM, and I/O with a typical start-up delay of 1-2
seconds.
2
Flammable Vapor Check
To insure no outputs are energized if flammable vapors
are present, the control pre-loads a condition indicating
flammable vapors are present. If no vapors are really
present, then the control resumes normal operation with
no perceptible delays. If vapors are present, the control
will immediately perform the flammable vapor lockout.
Heating Sequence
0
Idle
Normal operation
1
Heat demand
The control receives a demand for heat (the temperature
is less than set point minus differential).
2
Open pressure switch
The control checks the pressure switch to insure that it is
open.
3
Energize draft motor
The induced draft motor is energized.
4
Close Pressure switch
The control monitors the pressure switch until it closes.
5
Energize pilot and spark igniter
The pilot valve and spark igniter are energized (after the
Prepurge time).
6
De-energize spark igniter
The igniter is de-energized (when flame is proved above
the “Igniter Off” level).
7
Energize main gas valve
The main valve is energized (when flame is proved above
the “RUN” level).
8
Wait 3 seconds to stabilize flame
Flame and Pressure Switch signals are ignored for 3
seconds after the main valve is energized (Flame
Stabilization Period).
9
Temperature reaches setpoint
The demand for heat is satisfied (temperature reaches
set point).
10
De-energize the main and pilot gas valves The gas valves are de-energized.
11
Monitor Flame
Flame is monitored until flame signal drops below Flame
Lost level.
12
De-energize draft motor
The induced draft motor is de-energized (after the
Postpurge time).
