SEQUENCE OF OPERATION
–Power on.
–Heater in standby mode.
–Thermostat calls for heat.
–Blower motor starts.
–Blower operation closes the normally open blower prover/ blocked outlet safety pressure switch.
–On proof of airflow, Honeywell S8680J flame control module energized.
–45 seconds prepurge cycle begins.
–Following prepurge cycle, the pilot gas valve is energized.
–At the same time, the electronic spark generator in the module produces a high voltage spark pulse output.
–The voltage generates a spark at the ignitor that lights the pilot.
–If the pilot does not light (or flame signal is less than 1 micro
A)within 15 seconds system locks out and must be reset by turning burner switch “OFF” for a minimum of 1 minute. During system lockout, blower still runs.
–When the pilot flame is established (flame is sensed by flame rod), the main gas valve is energized.
–Main gas flows to main burner where it’s ignited by the pilot flame. Now heater is in Heating Mode.
–During the Heating Mode:
If gas line pressure drops below the setting point, the flame module is de-energized, gas valves closed, blower still runs.
If gas line pressure drops below the setting point then gas line pressure increases to above the setpoint, heater starts again from purging cycle.
If gas line pressure fluctuates around the setpoint too quick (less than a second) burner may still run with excessive gas valve ON/OFF cycle you must turn off the unit immediately, re-adjust the gas line regulator and/or install a larger gas supply line!
If the blower inlet and/or intake hood, or flue outlet/hood is/ are blocked for any reason, the safety switches will open, which will de-energize the flame control module.
–The spark generator is off.
–The flame module monitors pilot flame current. Should the flame failure occur during the Heating Mode, the unit will start again from purging cycle.
–Thermostat is satisfied, switch opens.
–Power is interrupted to the flame control module and blower motor. Gas valves are closed.
–Heater is in Standby Mode.
–Thermostat is satisfied, switch opens.
–Power is interrupted to burner, turning off blower and ignition control module. Solenoid and main gas valves are closed.
–Insufficient blower pressure causes safety pressure switches to open.
WATER TEMPERATURE CONTROL
DANGER
THIS WATER HEATER IS EQUIPPED WITH AN ADJUSTABLE THERMOSTAT TO CONTROL WATER TEMPERATURE. HOT WATER TEMPERATURES REQUIRED FOR AUTOMATIC DISHWASHER AND LAUNDRY USE CAN CAUSE SCALD BURNS RESULTING IN SERIOUS PERSONAL INJURY AND/OR DEATH. THE TEMPERATURE AT WHICH INJURY OCCURS VARIES WITH THE PERSON'S AGE AND TIME OF EXPOSURE. THE SLOWER RESPONSE TIME OF CHILDREN, AGED OR DISABLED PERSONS INCREASES THE HAZARDS TO THEM. NEVER ALLOW SMALL CHILDREN TO USE A HOT WATER TAP, OR TO DRAW THEIR OWN BATH WATER. NEVER LEAVE A CHILD OR DISABLED PERSON UNATTENDED IN A BATHTUB OR SHOWER.
THE WATER HEATER SHOULD BE LOCATED IN AN AREA WHERE THE GENERAL PUBLIC DOES NOT HAVE ACCESS TO SET TEMPERATURES.
SETTING THE WATER HEATER TEMPERATURE AT 120°F (49°C) WILL REDUCE THE RISK OF SCALDS. Some states or provinces require settings at specific lower temperatures.
Below you will find listed the approximate time-to-burn relationship for normal adult skin. Short repeated heating cycles caused by small hot water uses can cause temperatures at the point of use to exceed the thermostat setting by up to 20F°. If you experience this type of use, you should consider using lower temperature settings to reduce scald hazards.
Temperature | Time to Produce 2nd & 3rd |
Setting | Degree Burns on Adult Skin |
180°F (82°C) | Nearly instantaneous |
170°F (77°C) | Nearly instantaneous |
160°F (71°C) | About 1/2 second |
150°F (66°C) | About 1-1/2 seconds |
140°F (60°C) | Less than 5 seconds |
130°F (54°C) | About 30 seconds |
120°F (49°C) | More than 5 minutes |
| |
Valves for reducing point-of-use temperature by mixing cold and hot water are available. Also available are inexpensive devices that attach to faucets to limit hot water temperatures. Contact a licensed plumber or the local plumbing authority.
The water temperature is controlled by a thermostat, fig. 2, which has two sensing elements. One sensor is located near the top of the tank and the other is near the center. The thermostat is set in the lowest position before the heater leaves the factory.
The dial is adjustable and may be set for 1200 (49°C) to 1800F (82°C) water temperature, but 1200F (49°C) is the recommended starting point. It is suggested the dial be placed on the lowest setting which produces an acceptable hot water supply. This will always give the most energy efficient operation. The temperature control has a 4F° fixed differential.
ADJUSTMENT PROCEDURE (Initial Start-Up)
A minimum dynamic gas supply pressure of 8” w.c. for natural gas is required before making any adjustment to the gas control pressure regulator. Attempts to adjust the regulator during periods of low gas supply pressure could result in overfiring of the heater when the gas supply pressure returns to normal.
