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Фрагмент инструкции
Check for leaks. Measuring Manifold Pressure — LP Gas Units The main burner orifices on an LP gas unit are sized for the unit rated input when the manifold pressure is 3.5 in. wg. Proceed as follows to adjust gas input on an LP gas unit: a. Turn off gas to unit. b. Remove pipe plug on manifold (Fig. 22) then connect manometer at this point. c. Turn on gas to unit. d. Remove cover screw over regulator adjustment screw on gas valve. e. Adjust regulator adjustment screw for a manifold pressure reading of 3.5 in. wg. Turn adjusting screw clockwise to increase manifold pressure, or turn adjusting screw counterclockwise to decrease manifold pressure. f. Replace cover screw. g. Turn off gas to unit. Remove manometer from pressure tap. Replace pipe plug on gas valve, then turn on gas to unit. Check for leaks. —18— D. Check Burner Flame With burner access panel removed, observe the unit heating operation. Watch the burner flames to see if they are light blue and soft in appearance, and that the flames are approximately the same in appearance for each burner. See Fig. 23. Refer to maintenance section for information on burner cleaning and removal. BURNER FLAME E. Airflow and Temperature Rise The heating section of each unit size is designed and approved for heating operation within the temperature rise range stamped on the unit rating plate. Table 5 shows the approved temperature rise range for each rated heating input, and the air delivery cfm at various temperature rises. The heating operation airflow must produce a temperature rise that falls within the approved range. Refer to Indoor Airflow and Airflow Adjustments section on page 20, to adjust heating airflow when required. F. Heating Sequence of Operation See wiring diagrams in back of book and unit wiring label. On a call for heat, one of 2 Heating modes occurs, depending on the field setting of the economic balance point. The first Heating mode occurs when the outdoor temperature is warmer than the EBP. On a call for heat, the thermostat makes circuits R-Y and R-G. When compressor time delay (5 ± 2 minutes) is completed, a circuit is made to C, starting compressor (COMP) and outdoor-fan motor (OFM). Circuit R-G also is completed, energizing indoor-fan relay (IFR) and starting indoor-fan motor (IFM) after a 1-second delay. Should room temperature continue to fall, circuit R-W is made through second-stage thermostat bulb. One relay opens, turning off the compressor, and another relay is energized signaling the integrated gas control (IGC) board to bring on the gas heat. When the thermostat is satisfied, contacts open, deenergizing contactor and relay; motors and gas heater deenergize. The IFM may be controlled by a time-delay relay that keeps the fan on for 30 seconds. The second Heating mode occurs when the outdoor temperature is colder than the EBP. On a call for heat, the thermostat energizes the gas heat relay, signaling the IGC board to bring on the gas heat. In this Heating mode, both first- and second-stage heat is gas heating. When thermostat is satisfied, contacts open, deenergizing contactor and relay; motors and gas heater deenergize. The IFM may be controlled by a time-delay relay that keeps the fan on for 30 seconds. An LED (light-emitting diode) indicator is provided on the control board to monitor operation. The control board is located by removing the burner access panel. During normal operation, the LED is continuously on. See Table 6. Table 6 — LED Indications ERROR CODE LED INDICATION Normal Operation On Hardware Failure Off Fan On/Off Delay Modified 1 Flash Limit Switch Fault 2 Flashes Flame Sense Fault 3 Flashes Five Consecutive Limit Switch Faults 4 Flashes Ignition Lockout Fault 5 Flashes Inducer Switch Fault 6 Flashes Rollout Switch Fault 7 Flashes Internal Control Fault 8 Flashes NOTES: 1 There is a 3-second pause between code displays. 2 If more than one code exists, all applicable codes will be displayed in numerical sequence 3. This chart is on the wiring diagram located inside the burner access panel G. Limit Switches Normally-closed limit switch (LS) completes the control circuit through the thermostat R circuit. Should the leaving-air temperature rise above the maximum allowable temperature, the limit switch opens and the R control circuit “breaks.” Any interruption in the R control circuit instantly closes the gas valve and stops gas flow to the burners and pilot. The blower motor continues to run until LS resets. When the air temperature at the limit switch drops to the low-temperature setting of the limit switch, the switch closes and completes the R control circuit. The electric-spark ignition system cycles and the unit returns to normal heating operation. H. Auxiliary Limit Switch — Rollout The function of the switch is to close the main gas valve in the event of flame rollout. The switch is located above the main burners. When the temperature at the auxiliary switch reaches the maxi...