Sheet 4343-3 Page 4
TWINBED ® II PILOT SETUP AND TROUBLE-SHOOTING GENERAL SETUP — 4343 BURNER PILOT SYSTEM
CAUTION! Standards-compliant functioning of the Flame Detection System can be compromised if the pilot system is not configured and adjusted strictly in accordance with the information outlined in Sheet 4343-3. Refer to pilot schematic on page one for item numbers. 1. All fuel valves to furnace should have been closed during shutdown (both main and pilot valves). 2. Purge the furnace in accordance with local standards requirements. 3. Adjust the main burner air flow to its lowest operating condition (for instance, with air flow conditions of a hot regenerator at light-off). 4. Open manual gas shutoff valves (not shown on schematic) to get gas pressure to inlet of closed pilot manual valve . Set gas supply pressure to pilot system between 21 and 28"w.c. Note: Gas pressure must be set when gas is flowing. Make final adjustments to gas supply pressure once pilot is burning. 9 Warning: Startup and adjustment of combustion equipment should only be done by trained personnel familiar with combustion technology, combustion equipment, and with the particular burner system, equipment, and controls. 5. Turn open six turns the adjustment plug of the pilot gas limiting orifice valve . 6. Place the 4343 Burner in stop cycle mode (main burners off, blower running). 7. Set the pilot air regulator for a 7"w.c. pressure measured at the cooling air needle valve . Refer to "Air Supply to Pilot/Cooling Air Regulator" on page 2 for air pressure information. 8. Set fuel-tube cooling-air pressure at item to 1"w.c. 1 12 7 2
9. Make sure UV cooling air valves is open and air is flowing to UV mounting adapter. 10. Run trial for pilot ignition (power ignition transformer and open pilot gas solenoid valve 15 17
). Slowly open pilot gas
10
shutoff valve . Adjust pilot gas limiting orifice valve 9
until 4.3"w.c. is measured at the pilot gas pressure tap .
12
13
The pilot should ignite. 11. CAUTION! Verify that the pilot flame cannot be sensed by the main flame scanner, as this could permit a hazard to persist, and is indicative of a pilot setup issue. If the main flame scanner senses the pilot flame, confirm settings, readjust pilot and burner settings and retest until the main flame scanner dœs not sense the pilot flame. 12. If pilot does not ignite, see page 5.
TWINBED ® II PILOT SETUP AND TROUBLE-SHOOTING TROUBLE-SHOOTING 4343 PILOT SYSTEM
Problem Possible Cause
Possible Correction
A. Pilot dœs not light 1. No spark.
Check spark plug for carbon or no gap; ignition transformer ; and ignition wire for electrical continuity, short or failed/burned insulation. 17 18 14a
2. Pilot tip dirty or plugged. 3. Pilot air pressure is not correct. 14a
Clean.
Measure with a manometer when the main burner is in stop cycle mode. If not correct, adjust pilot air regulator
accordingly. 1
4. Pilot gas pressure is not correct.
Measure with a manometer when the main burner is in stop cycle mode. If not correct, adjust pilot gas needle valve accordingly. 12
5. Pilot gas solenoid valve 6. Pilot manual gas valve
not opening.
Check for power to gas solenoid valve.
10
closed.
Open.
9
B. Pilot gœs out after lighting:
1. Pilot tip dirty or plugged. 14a
Clean.
2. Pilot flame rod
not seeing flame.
Clean or replace flame rod
.
14b
14b
3. Incorrect pilot air pressure. 4. Incorrect pilot gas pressure
Adjust air butterfly valve . Adjust gas needle valve . 12 3
5. Incorrect upstream pressure to ratio regulator
.
See setup instructions (above) and adjust.
11
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