Assessments - 4, GPA: 4.5
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Connect a manometer to the pressure ports shown in Figure 20. Make sure that the gas supply piping has been purged of air and that all gas joints up to the gas valve have been thoroughly checked for leaks. Wait at least five minutes for any gas to dissipate before turning on the electrical power. C. Raise the thermostat at least 5 degrees above the room temperature. A delay of about 30 seconds will take place as the silicon carbide ignitor heats up. Once the ignitor is hot, the main gas valve will open and the burner should light. If the burner fails to light the system will make two more ignition attempts. If the burner lights, but goes out within 4 seconds, the system will make three ignition attempts. If the burner has not lit after the last ignition try, the gas valve will close and the system will go into lock out. DO NOT attempt to reset the system until the ignition system has been inspected and the problem resolved. Once the problem has been resolved and 5 minutes have passed since the last ignition attempt, reset the system by turning the thermostat to it's lowest setting and then back to where it was or by momentarily interrupting the electrical power to the boiler. D. With the burner in operation the manometer should show 1.9" W.C. manifold pressure. If not, see the BOILER CHECKING & ADJUSTMENT section. Close the manual shutoff valve in the gas supply line. As soon as the burner flame goes out, open the manual shutoff valve. A normal ignition sequence should take place. E. With the burner in operation, interrupt the power to the control circuit by lowering and raising the thermostat. A normal ignition sequence should follow. F. To test the ignition safety shutoff device, close the manual shutoff valve in the gas supply line. Within 6 seconds of main burner flame extinction, the main gas valve solenoid should close with an audible noise. The igniter should glow and make three attempts at ignition. After unsuccessfully attempting to light the burner the ignition module should lock out. Open the manual shutoff valve in the gas supply line. Reset the ignition control system by interrupting, then restoring electrical power to the boiler. A normal ignition sequence should take place. GS110 DIRECT VENT BOILER INSTALLATION AND OPERATION INSTRUCTIONS Page 25 Figure 20- Air and Manifold Pressure BOILER CHECKING & ADJUSTMENT INPUT RATE Gas appliances are rated based on sea level operation with no adjustment required at elevations up to 2000 feet. At elevations above 2000 feet, input ratings should be reduced by 4% for each 1000 feet above sea level. Check the input rate as follows: NATURAL GAS: 1. Turn off all other gas appliances that use the same gas meter as the boiler. 2. Call the gas company for the gas heating value. 3. Start the boiler and let it run for 15 minutes. 4. Using the gas meter and a stopwatch, clock the time that it takes to burn 10 cubic feet of gas and divide the time by 10. 5. Insert the heating value and the time, in seconds, into the formula below. Input Rate = Heating Value(Btu/ft3)(3600 s/hr) Flow Rate(s/ft3) EXAMPLE: If the heating value = 1000 Btu/ft3 and the flow rate = 36 s/ft3 Input Rate = (1000 Btu/ft3)(3600 s/hr) 36 s/ft3 Input Rate = 100,000 Btu/hr If the computed rate deviates by more than 5% from the rated input value of the unit adjust the gas valve pressure accordingly. DO NOT adjust the manifold pressure by more than 5%. If a proper rate cannot be maintained without adjusting the manifold pressure beyond the 5% limit, the burner orifice must be replaced. If the input rate is too low go to the next larger size orifice. if the input rate is too high, go to the next smaller size orifice. PROPANE GAS: The input rate for LP units is factory set based on the orifice size. The manifold pressure must be set at 1.9" W.C. and the orifice supplied with the boiler used unless the unit is to be derated for altitude. CAUTION: Never increase the input to the boiler above that for which it is rated. Doing so can cause premature failure of the boiler! GAS PRESSURE ADJUSTMENT NATURAL GAS: Optimum results are obtained when the boiler is operated at its full input rating, with 1.9" W.C. of manifold pressure. The manifold pressure should not be more that 5% off this value. The gas valve pressure regulator has been preset at the factory. If adjustment is necessary the following steps must be followed: 1. Connect each side of a manometer to the two pressure ports shown in Figure 20 to obtain the manifold pressure. 2. Connect a flue gas analyzer to the vent pipe. 3. Rotate the regulator adjustment screw clockwise to increase the manifold pressure, counterclockwise to decrease it. Never force the regulator adjustment screw or the gas valve will be damaged! 4. The CO2 reading should fall between 7% and 9% with a CO reading of less than 50 ppm air free. 5. Adjust the air damper using the screw on the front of the filter box if the CO2 and CO readings are not within the range given in step 4. 6. ...