Assessments - 4, GPA: 4.3 ( )

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The device may be tested after disconnecting the four leads from their respective terminals on the unit. 1. Apply a test light to the yellow and red leads: • The lamp should light as the contact in this circuit is normally closed when the resistor is cool. 2. Apply the light to the black and yellow leads. • The lamp should not light as the contact in this circuit is normally open when the resistor is cool. 3. Remove the test light. 4. Apply 120 volts to the white and red leads which power the 1900 ohm resistor. • After warming period, the contacts of the thermal balancer should change position. 5. Remove the 120 volt power source. 6. Apply the test light as described in steps 1 and 2. • While the resistor is still warm, the lamp indications should be the opposite as described above. If this is not the case, replace the thermal balancer. THERMAL BALANCER SCHEMATIC DIAGRAM FIGURE 16 INSPECTING THE HEAT EXCHANGER AND VENTING SYSTEM Every 6 months, inspect the venting system (including the chimney) for blockages which will retard free draft and points of flue gas leakage. Remove any obstructions and replace any damaged or deteriorated vent pipe. Check the heat exchanger to be sure it is not blocked by dirt or soot. It is not sufficient to only look through the flue outlet with the draft hood removed. Examination should also be made using a mirror and light through the burner opening, viewing the entire bottom area of the exchanger. Qualified servicers should follow this procedure when the heater’s external heating surfaces need cleaning. 21 CAUTION DO NOT USE A NYLON BRUSH OR OTHER STATIC CREATING MATERIAL TO CLEAN DUST AND CARBON DEPOSITS FROM HEATING SURFACES AND VENT. SUCH DEPOSITS ARE FLAMMABLE AND MAY BE IGNITED BY STATIC ELECTRICITY. USE A METAL BRUSH TO MINIMIZE THE DANGER OF EXPLOSION. 1. Turn off the electrical power and main manual gas shutoff valve. • Allow heater parts and vent to cool before disassembly. 2. Remove the heater draft diverter and vent pipe running to the chimney. • Check parts and chimney for obstructions and clean as necessary. • Replace any damaged or deteriorated parts of the venting system. 3. Remove burners from heater and other metal parts as required to clean and vacuum the heat exchangers and combustion coils. • Refer to parts list supplied with this manual for disassembly aid. 4. Reinstall the parts removed in steps 2 and 3. • Be sure the vent pipe has a minimum upward pitch of one quarter inch per foot of length and is sealed as necessary. 5. Restore electrical power and gas supply to heater. • Check for gas leaks and proper heater and vent operation. Upon reassembly, a negative draft must be produced by the system. Check for proper draft by holding a lit match near the draft hood opening while the heater is operating. The flame should be drawn into the draft hood opening indicating proper draft. GAS PRESSURE REGULATOR The gas pressure regulator is included in the combination gas valve, fig.14, and is set to operate on the gas specified on the heater model and rating plate. Periodically check main burner, fig. 13, and pilot flame, fig. 15, for proper operation. This should be checked every six months. Do not subject the gas valve to inlet gas pressure of more than 10.5" W.C. - natural gas, 13.0" W.C. - propane gas. If higher gas pressures are encountered, a service regulator is necessary. Check for a minimum inlet gas pressure value shown on the Rating Plate before making any adjustment of the 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. DO NOT INCREASE PRESSURE ABOVE THAT SPECIFIED AS OVERFIRING WILL RESULT IN DAMAGE TO THE HEATER . If gas pressure regulator cannot be adjusted to correct pressure PREVENTIVE MAINTENANCE RECOMMENDED PROCEDURE FOR PERIODIC REMOVAL OF LIME DEPOSITS FROM COIL TYPE COMMERCIAL WATER HEATERS The amount of calcium carbonate (lime) released from water is in direct proportion to water temperature and usage, see fig. 17. with sufficient gas pressure at the valve, replace with new gas valve. RELIEF VALVE At least twice a year the system relief valves should be checked to ensure that they are in operating condition. To check a relief valve, lift the lever at the end of the valve several times. The valve should seat properly and operate freely. CAUTION BEFORE MANUALLY OPERATING A RELIEF VALVE, MAKE SURE THAT A DRAIN LINE HAS BEEN ATTACHED TO THE VALVE TO DIRECT DISCHARGE TO AN OPEN DRAIN. FAILURE TO TAKE THIS PRECAUTION COULD MEAN CONTACT WITH EXTREMELY HOT WATER EXITING THE VALVE DURING THE CHECK OPERATION. If a relief valve discharges periodically or continuously, it may be due to thermal expansion of water in a closed water supply system, or, it may be due to a faulty relief valve. Thermal expansion is the normal response of water when it is heated. In a closed system, thermal expansion will cause the system pressure to buil...

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