2525 W CASINO RD BASE FILE 2025-01-03

service diagnosis 2. YELLOW TIPPING. Yellow tipping of a normally blue 5. FLOATING FLAMES.floating flames are long—do not flame is caused by insufficient primary air, and indicates have well-defined cones, roll around in the combustion incomplete combustion producing carbon monoxide, chamber, sometimes completely off the ports. Usually an aldehydes, and free carbon (soot). A dirty orifice or one aldehyde odor is present to indicate incomplete combus- that is out of line can also reduce primary air and cause tion. If secondary air supply is reduced too far, burner yellow tipping. Check orifice, clean, realign, or replace flames will float. Often the pilot .flame near the port if necessary. With propane gas, some yellow tipping is smothers and goes out. Lack of combustion air causes always present, but is not objectionable. burner flames to float.The unit maybe overfired so its flue outlet area may be too small for the increased firing rate. 3. FLASHBACK, Flashback occurs when air-gas mixture Check input rate and reduce if necessary.Soot or dust may ignites inside the burner to burn near the orifice. Flash- be blocking the flue. Check flue and clear any blockage. back on ignition or during burner operation usually can Adjust primary air to get rid of yellow tipping tht may be eliminated by reducing primary air. The burner may produce soot to block flueways. Make sure combustion air also be operating below its rated capacity. Check input inlets are not blocked. rate and adjust to correct value by increasing orifice size or manifold gas pressure. (,L s5 r , GOOD BAD Figure 19 Flame rollout appearance 6. FLAME ROLLOUT. Flames rolling out of the combus- tion air inlets when the burner is turned on can create a fire hazard, scorch unit finish, burn wires, or damage controls. Gas in the burner mixer may be ignited, pro- ducing flashback. Flame rollout is a variation of floating flames, with flames reaching for air outside the combus- tion chamber. Basic cause is lack of combustion air that may be due to overfiring, poor draft, or flue blockage. Fi ure 17 STANDING PILOT SYSTEMS 1 9 Wavering flame or misalignment IF PILOT DOES NOT LIGHT 1. Check gas supply to pilot. 4. WAVERING FLAMES. Drafts across burners may 2. Bleed air from pilot line. (Use special care In bleeding cause flames to waver or appear unstable. Wavering propane units.) flames can lead to incomplete combustion if flames impinge on cool surfaces. Wavering can be caused by air 3. If pilot sputters, check pilot line for condensate or drafts into the burner compartment or diverter relief other obstruction. opening or by misalignment of the burner. Draft-blown 4. If flame is feeble,orshort,check pilot orifice for cleanli- flames may indicate a cracked heat exchanger. ness. Replace if necessary. 5. Be sure thermocouple contact point is clean.If problem persists,replace thermocouple and/or pilot safety valve. If unit is equipped with an ECO (energy cut-off device located on rear panel of unit.) Check fuse in ECO and make sure it has not blown and is operating correctly. Caution:The ECO fuse should blow only if excessive unit temperatures are experienced.If fuse is blown make sure the cause of the unit overheating is found and corrected before replacing the fuse and placing the unit back into operation. 6. If the above steps do not correct the condition,consult your local gas company, or local Modine factory representative. IF STANDING PILOT DOES NOT STAY LIT 1. Check manifold pressure with all units operating making certain that there is proper pressure. 2. Check pipe or tubing size to unit. See Table 1. 3. Be sure all pilot connections are tight. Figure 18 4. Check for excessive drafts. Floating flame condition 5. Check for clogged pilot orifice or pilot line. 6. Check for leaks around pilot fittings. If leaks cause flame impingement on thermocouple lead, thermo- Page 22 couple may become inoperative.