Whirlpool EDP/EDN warranty Gas Valve Calibration, Symptom Evaluations, 10A. Delayed ignition

Endurance Page 31

observe the offset pressure at startup and after 20 seconds. The pressure will be ~ -2 in. w.c. at startup (during prepurge) and should become less negative (-0.1 in. w.c.) when the gas valve opens and gas flow starts. If the pressure remains at ~ -2 in. w.c. throughout the cycle replace the gas valve.

4.Ignitor failure: If the boiler goes through a normal start cycle but combustion does not occur, ignitor failure should be suspected.

Check the ignitor by unplugging the ignitor plug and measuring the ignitor resistance. It should be 50-100 (￿) ohms. If the resistance is not 50-100 ohms (￿), replace the ignitor. If the resistance is correct, reset the boiler and check for 120 VAC at the ignitor plug during the start cycle. If there is no voltage, replace the PCB or faulty ignitor wires.

5.Blocked or contaminated air source: Before proceeding, ensure that the vent terminal (Direct Vent installations) or the air inlet (Category IV installations) is not obstructed. In general, only direct vent installations have the potential for cross contamination (flue products entering the combustion air stream) of the combustion air source. This may be caused by leaky joints in the 3" flue pipe located inside the 5" combustion air pipe. If this is suspected, remove the front panel from the appliance, reset the boiler and allow it to go through a normal cycle. If during this cycle there is no flue odor, repair the leaky joints in the flue pipe.

SECTION 9.

Gas Valve Calibration

9A. Gas Valve Calibration (offset adjustment)

If poor combustion is suspected because of a strong exhaust smell, pulsation in the exhaust, or nuisance flame failure lockouts (shown as “LO” on LED), the gas valve offset pressure and exhaust CO2 should be checked and adjusted, if required. A magnehelic pressure gauge (with 0.1 in. w.c. divisions) and a CO2 tester are required for this adjustment.

Note: Direct vent installations may experience poor combustion that results from cross contamination of the combustion air source. Check for cross contamination before attempting offset pressure adjustment (see Section 8B-3.5).

CO2 sampling may be taken at the exhaust terminal or at the sample port on the 3” exhaust located inside the front panel top cover. See Figure 28 for the location of the offset pressure port and offset adjustment.

The CO2 values shown in Table 4 should be achieved when the unit is in high fire. To manually fix the unit in high fire, locate the four-pin connector on the bottom left of the control board, and jumper the middle two terminals together (see Figure 29). NOTE: For EBP (combination heat & hot water) units, when the unit is in “tank charge” mode it will stay in high fire, whether manually jumpered or not.

Note: During the prepurge cycle, the gauge will indicate several in. W.C. negative pressure.

Adjust the CO2 and/or offset pressure to the values shown in Table 4.

When adjusting the offset pressure, the CO2 will reduce as the offset pressure is adjusted more negative. FINAL ADJUSTMENT OF THE

OFFSET PRESSURE MUST ALWAYS RESULT IN A NEGATIVE PRESSURE UPON COMPLETION.

SECTION 10.

Symptom Evaluations

10A. Delayed ignition

Possible Causes

a.High lockup pressure (LP boilers) - occurs on start-up.

b.Gas valve regulation problem - occurs on start-up.

c.Incorrect gas orifice (Natural gas orifice in an LP boiler) - occurs on start up

d.Defective burner - occurs on startup or at burner

shutdown.

High lock up pressure is the most common cause of delayed ignitions on LP fueled boilers. It may result from an improper second stage regulator selection or from a faulty regulator.

Lock up can be detected by measuring the gas supply pressure to the boiler at the inlet pressure tap on the gas valve. The gas supply to the boiler must be shut off before making this connection. Use a water manometer or pressure gauge with a scale reading of at least 25 in. w. c. or 15 oz/in2. Loosen the screw in the gas valve pressure port one full turn and install a hose from the pressure gauge over the pressure port. Turn on the gas supply. The ENDURANCE boiler is designed to operate with supply pressures of 4-13 in. w. c. (2.3 - 7.5 oz/ in²). If the supply pressure exceeds 13 in. w. c. (7.5 oz/ in²) with the boiler not operating it is possible that this may be the cause of delayed ignitions and the pressure must be reset to ~ 9 in. w. c. (5.2 oz/ in2). Restart the boiler and then switch it off again. Lock up pressures must be measured when the boiler is not operating and preferably immediately after boiler shutdown. If the gas pressure again exceeds the allowable values, correct the lock up problem.