A.O. Smith BT- 80 Service Information, High Temperature Limit Switch, Pilot and Main Burner

WARNING

FAILURE TO CORRECT BACK DRAFTS MAY CAUSE AIR CONTAMINATION AND UNSAFE CONDITIONS.

•If the back draft cannot be corrected by the normal method or if a suitable draft cannot be obtained, a blower type flue gas exhauster must be employed to assure proper venting and correct combustion.

HIGH TEMPERATURE LIMIT SWITCH

(Auto Reset Type Energy Cut Off)

TO RESET AUTOMATIC GAS SHUTOFF

This water heater is equipped with a automatic reset type high limit (Energy Cutoff) sensor. The high limit switch interrupts the pilot and main burner gas flow should the water temperature reach 205°F(96°C). The high limit will automatically reset when the water temperature drops below 140°F (60°C).

WARNING

THE GAS VALVE MUST HAVE BEEN IN THE OFF POSITION FOR AT LEAST 5 MINUTES. This waiting period is an important safety step. Its purpose is to permit gas that may have accumulated in the combustion chamber to clear. IF YOU DETECT GAS ODOR AT THE END OF THIS PERIOD DO NOT PROCEED WITH LIGHTING. RECOGNIZE THAT GAS ODOR, EVEN IF IT SEEMS WEAK, MAY INDICATE PRESENCE OF ACCUMULATED GAS SOMEPLACE IN THE AREA WITH RISK OF FIRE OR EXPLOSION. SEE THE FRONT PAGE FOR STEPS TO BE TAKEN.

Before lighting the pilot and operating the heater, the following conditions must exist:

•Entire system filled with water.

•Air purged from all lines and no leaks (gas and water).

•All gas and water lines open.

SHOULD OVERHEATING OCCUR OR THE GAS SUPPLY FAIL TO SHUT OFF, TURN OFF THE MANUAL GAS CONTROL VALVE TO THE APPLIANCE.

SERVICE INFORMATION

The installer may be able to observe and correct certain problems which may arise when the unit is put into operation. HOWEVER, it is recommended that only qualified servicemen, using appropriate test equipment, be allowed to service the heater.

FOR YOUR SAFETY AND SATISFACTORY OPERATION, IT IS RECOMMENDED THAT THIS HEATER BE CHECKED ONCE A YEAR BY A COMPETENT SERVICE PERSON.

USERS OF THIS APPLIANCE SHOULD BE AWARE THAT GAS COMPONENTS WEAR OUT OVER A PERIOD OF TIME. THE GAS CARRYING COMPONENTS OF THIS APPLIANCE SHOULD BE INSPECTED FOR PROPER OPERATION PERIODICALLY BY A QUALIFIED SERVICE TECHNICIAN.

PILOT AND MAIN BURNER

Check pilot and main burner (figure 8) every 12 months for proper flame characteristics. This is done by removing door(s) on heater. The main burner should provide complete combustion of gas;

ignite rapidly; give reasonably quiet operation; cause no excessive flame lifting from the burner ports. Make sure that the flow of combustion and ventilation air is not blocked.

PROPANE

NATURAL

FIGURE 8

If proper flame characteristics are not evident, check for accumulation of lint or other foreign material that restricts or blocks the air openings in the heater or burner.

WARNING

SOOT BUILD-UP INDICATES A PROBLEM THAT REQUIRES CORRECTION BEFORE FURTHER USE. CONSULT WITH A QUALIFIED SERVICE TECHNICIAN.

Should the main burner or burner air openings require cleaning, turn off the gas to the water heater. Follow "to turn off gas to appliance" on pages 10 and 11 and allow the burner to cool. Remove the burner and clean with a soft brush. Clean main burner orifice with a suitable soft material. Follow lighting instructions on pages 10 and 11 to put the water heater back in operation.

CHECK FOR GOOD FLOW OF COMBUSTION AND VENTILATING AIR TO THE UNIT. MAINTAIN A CLEAR OPEN AREA AROUND THE HEATER AT ALL TIMES. DO NOT STORE COMBUSTIBLES OR FLAMMABLE LIQUIDS NEAR OR AROUND AN APPLIANCE.

CHECKING GAS INPUT

For appliance installation locations with elevation above 2000 ft.(610m) refer to HIGH ALTITUDE INSTALLATIONS section of this manual for input reduction procedure.

With this heater in operation, determine whether it is receiving the full rated input of gas. This may be done by timing the gas meter and measuring gas pressure with a gauge or manometer. When the heater is operating at full capacity (full gas input) it should consume approximately 1 cubic foot of gas in the time shown in table 3.

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