Tags: Troubleshooting

Troubleshooting Gas Burners

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As is the case with all mechanical and electrical equipment, it is recognized that occasional repair and adjustment may be necessary on any burner. Table 2-4 represents a very general list of troubles and causes that can occur with gas burners and gives some suggested remedies.

Table 2-4 Troubleshooting Gas Burners

Symptom and Possible Cause Possible Remedy
Pilot does not light.
(a) Air in gas line. (a) Clear or replace line.
(b) High or low gas pressure. (b) Check for possible gas supply problem with local gas company; replace defective burner.
(c) Blocked pilot orifice. (c) Clean orifice or replace.
(d) Flame runner improperly located. (d) Move to correct location.
Pilot goes out frequently during standby or safety switch needs frequent resetting.
(a) Restriction in pilot gas line. (a) Clear or replace line.
(b) Low gas pressure. (b) Check for possible gas supply problem first with local gas company; Replace defective burner.
(c) Blocked pilot orifice. (c) Clear blockage or replace.
d) Loose thermocouple connection on 100 percent shutoff. (d) Secure connection or replace defective thermocouple.
(e) Defective thermocouple or pilot safety switch. (e) Replace thermocouple or pilot safety switch.
(f) Poor draft connection. (f) Correct.
(g) Draft tube set into or flush with inner wall of combustion chamber. (g) Move tip of draft tube to proper location.
Pilot goes out when motor starts.
(a) Restriction in pilot gas line. (a) Remove restriction or replace line.
(b) High or low gas pressure. (b) Check for possible gas supply problem with local gas company; replace defective burner.
(c) Excessive pressure drop when main gas valve opens. (c) Check for possible gas supply problem with local gas company; test main gas valve and replace if defective.
Burner motor does not run.
(a) Burned-out fuse or tripped circuit breaker. (a) Replace fuse or reset circuit breaker. If problem continues, call an electrician.
(b) Thermostat or limit defective or improperly set. (b) Reset thermostat or limit, or replace if defective.
(c) Relay or transformer defective. (c) Replace relay or transformer.
(d) Motor burned out. (d) Replace motor or burner.
(e) Tight motor bearings from lack of oil. (e) Lubricate bearings; repair or replace damaged bearings.
(f) Improper wiring. (f) Check wiring diagram for burner and rewire correctly.
Burner motor running but no flame.
(a) Pilot out. (a) Relight pilot or replace defective pilot.
(b) Pilot safety switch needs to be reset. (b) Reset switch.
(c) Thermocouple not generating sufficient voltage. (c) Replace defective thermocouple.
(d) Very low or no gas pressure. (d) Check for possible gas supply problem with local gas company; check for obstruction in gas line and correct.
(e) Motor running too slow. (e) Replace defective motor.
Short and/or noisy burner flame.
(a) Pressure regulator set too low. (a) Change to proper setting.
(b) Air shutter open too wide. (b) Correct opening size.
(c) Too much pressure drop in gas line. (c) Check for possible gas supply problem with local gas
company; check for obstruction in gas line and correct.
(d) Vent in regulator plugged. (d) Clear vent.
(e) Defective regulator. (e) Replace regulator.
Long yellow flame.
(a) Air shutter not open enough. (a) Adjust opening.
(b) Air openings or blower wheel clogged. (b) Clear.
(c) Too much input. (c) Reduce input.
Main gas valve does not close when blower stops.
a) Defective valve. (a) Replace valve.
(b) Obstruction on valve seat. (b) Remove obstruction.

Troubleshooting the Oil Burner Primary Control

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Table 5-4 lists possible remedies to a number of different operating problems associated with oil burner primary controls. Before checking the primary control, examine the following parts of the oil burner and ignition systems:

• Main power supply and burner motor fuse
• Ignition transformer
• Electrode gap and position
• Contacts between ignition transformer and electrode

Other system components that should be checked before examining the primary control are the oil piping to the tank, the oil filter, oil pump pressure, oil nozzle, and oil supply.

Table 5-4 Troubleshooting Oil Burner Primary Control

Symptom and Possible Cause Possible Remedy
Repeated safety shutdown.
(a) Slow combustion thermostat response. (a) Move combustion thermostat to better location. Adjust for moreefficient burner flame. Clean surface of cad cell.
(b) Low line voltage. (b) Check wiring and rewire if necessary. Contact local power company.
(c) High resistance in combustion thermostat circuit. (c) Replace combustion thermostat.
(d) High resistance in thermostat or operating control circuit. (d) Check circuit and correct cause.
(e) Short cycling of burner. (e) Clean filters. Reset or replace differential of auxiliary controls. Repair or replace faulty auxiliary control. Set thermostat heat anticipation at higher amp value. Clean holding circuit contacts.
(f) Short circuit in combustion thermostat cable. (f) Repair cable or replace combustion thermostat.
Relay will not pull in.
(a) No power; open power circuit. (a) Repair, replace, or reset fuses, line switch, limit control, auxiliary controls.
(b) Open thermostat circuit. (b)With power to relay, momentarily short thermostat terminals on relay. If burner starts, check wiring.
(c) Combustion thermostat open. (c) Repair or replace combustion thermostat.
(d) Ignition timer contacts open. (d) Clean magnet.
(e) Open circuit in relay coil. (e) Replace relay.

Troubleshooting Thermocouples

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Table 5-2 lists possible remedies for a number of different operating problems associated with thermocouples.

Symptom and Possible Cause Possible Remedy
Pilot flame lit but safety control fails to function.
(a) Thermocouple not hot enough to generate current. (a) Wait at least 1 minute for thermocouple to become hot enough.
(b) Drafts deflecting flame away from thermocouple. (b) Eliminate source of draft.
(c) Pilot flame too small or yellow in color due to restricted pilot line or dirt in primary air opening or burner head. (c) Disconnect, clean thoroughly, and reconnect. Change orifice if necessary.
(d) Loose or dirty electrical connections. (d) Disconnect, clean, reconnect, and tighten.
(e) Thermocouple tip too low in pilot flame mounted in bracket. (e) Check installation to make sure thermocouple is properly.
Safety control operates but fails when main burner has been on a short time.
(a) Restriction in pilot or main gas tubing. (a) Eliminate restriction. Provide normal pressure.
(b) Draft-deflecting flame couple. (b) Eliminate draft or baffle.

Troubleshooting Humidistats

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Read the humidistat manufacturer’ s installation and operating manual for troubleshooting problems, their possible causes, and their suggested remedies. In most cases, they will be specific to the type of humidistat (electromechanical, electronic, or pneumatic) and the model. Some very basic troubleshooting problems that apply uniformly to all humidistats are listed in Table 4-4.

Table 4-4 Troubleshooting Humidistats

Problem and Possible Cause Suggested Remedy
Slow response.
(a) Humidifier installed in a dead air space. (a) Relocate to appropriate location.
(b) Inadequate airflow caused by an incorrect cover. (b) Install a correct cover.
Inaccurate reading.
(a) Backplate too tight. (a) Retighten.
(b) Humidistat installed on inside surface of an outside wall. (b) Move to appropriate location.
(c) Humidistat installed near heat source. (c) Move nonpermanent heat source (lamp, TV set, etc.) away from humidistat or move humidistat away from permanent heat source (constant sunlight, fireplace, stove, etc.).
Constant readings.
(a) Defective humidistat. (a) Replace humidistat.
(b) Incorrectly calibrated humidistat. (b) Recalibrate humidistat.
(c) Humidistat is undersized. (c) Replace the humidistat with a correctly sized one.

Troubleshooting Thermostats

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Thermostat problems are sometimes the result of poor wiring connections. Check the wiring first. You should also make certain that the fan and system switches and the temperature setpoint are properly set.

The troubleshooting chart in Table 4-3 includes many of the more common symptoms and possible causes of operating problems associated with thermostats.

Table 4-3 Troubleshooting Thermostats

Symptom and Possible Cause Possible Remedy
Room temperature overshoots thermostat setting (too cold).
(a) Thermostat not mounted level (mercury-switch types). (a) Remount thermostat in level position.
(b) Thermostat not properly calibrated. (b) Recalibrate or replace.
(c) Thermostat exposed to heat source. (c) Move thermostat to better location.
(d) Thermostat setpoint too low. (d) Reset.
(e) System sized improperly. (e) Determine correct sizing and make system adjustments.
Room thermostat does not reach setting (too warm).
(a) Thermostat subject to draft. (a) Wiring hole may not be plugged. Move thermostat to better position.
(b) Thermostat not mounted level (mercury-switch types). (b) Remount thermostat in level position.
(c) Thermostat not properly calibrated. (c) Recalibrate or replace.
(d) Thermostat setpoint too high. (d) Reset.
(e) System sized improperly. (e) Determine correct sizing and make system adjustments.
(f) Thermostat damaged. (f) Replace thermostat.
System cycles too often.
(a) Thermostat exposed to heat source. (a) Relocate thermostat.
(b) Thermostat differential too small. (b) Reset or replace thermostat.
(c) Thermostat heating element improperly set. (c) Reset or replace thermostat.
(d) Thermostat subject to vibrations. (d) Remount thermostat in location free from vibrations.
(e) Thermostat exposed to cold draft. (e) Remount in better location.
System does not cycle often enough (burner operates too long).
(a) Thermostat not exposed to circulating air. (a) Remount in better location.
(b) Contacts dirty. (b) Clean or replace.
(c) System sized improperly. (c) Determine correct sizing and make system adjustments.
(d) Thermostat differential too great. (d) Reset or replace thermostat.
(e) Thermostat heating element improperly set. (e) Reset or replace thermostat.
(f) Thermostat set too high. (f) Reset.
Room temperature swings excessively.
(a) Thermostat not exposed to circulating air. (a) Remount in better position.
(b) Thermostat exposed to heat source. (b) Remount in better position.
(c) System sized improperly. (c) Determine correct sizing and make system adjustments.
Thermostat jumpered (system works).
(a) Thermostat contacts dirty. (a) Clean or replace.
(b) Thermostat setpoint too high. (b) Reset or replace thermostat.
(c) Thermostat damaged. (c) Replace thermostat.
(d) Break in thermostat circuit. (d) Locate and correct.
Burner fails to stop.
(a) Thermostat in cold location. (a) Relocate in better location.
(b) Thermostat set too high. (b) Reset.
(c) Defective thermostat. (c) Replace thermostat.
d) Thermostat out of adjustment. (d) Recalibrate or replace thermostat.
(e) Thermostat contacts stuck. (e) Correct.

Troubleshooting Coal Stokers

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All mechanical devices occasionally malfunction or operate below a commonly accepted level of efficiency. Coal stokers are no exception to this rule. Table 3-1 lists the conditions that indicate faulty operation:

Table 3-1 Troubleshooting Coal Stokers

Symptom and Possible Cause Possible Remedy
Abnormal noises.
(a) Loose pulleys or belt. (a) Tighten or replace.
(b) Dry motor bearings. (b) Oil the bearings.
(c) Worn gears. (c) Oil or replace.
(d) Gears lack oil. (d) Oil the gears.
Motor will not start.
(a) Hard clinkers over or on retort. (a) Remove the clinkers.
(b) Foreign matter caught in the feed screw. (b) Remove the foreign matter.
(c) Packing of coal in the retort caused by the end of the feed screw being worn. (c) Remove packed coal from the retort and replace feed screw.
Stoker operates continuously.
(a) Controls out of adjustment. (a) Contact manufacturer for a service call.
(b) Dirty fire. (b) Rebuild or clean fire.
(c) Fire out. (c) Rebuild fire.
(d) Dirty furnace or boiler. (d) Clean furnace or boiler.
Furnace filled with unburned coal.
(a) Clinkers clogging the retort. (a) Remove the clinkers.
(b) Coal feed set too high. (b) Reduce coal feed setting.
(c) Insufficient air getting to the fire. (c) Open manual damper. If this does not help, check air ports for clogging. Also, check the windbox. If it is full of siftings, they should be removed.
(d) Windbox filled with siftings. (d) Empty windbox.
Stoker will not run.
(a) Limit control has shut off furnace or boiler due to overheating. (a) Allow limit control time to cool off.
(b) Low-water cutoff has shut down the boiler. (b) Check water level in boiler and correct.
(b) Low-water cutoff has shut down the boiler. (b) Check water level in boiler and correct.
(c) Gear case has been exposed to water. (c) Do not try to operate the stoker. Drain and flush out the gear case immediately and refill with oil.
(d) Blown fuse. (d) Replace fuse.
(e) Tripped circuit breaker. (e) Reset circuit breaker.
Smoke backed into hopper.
(a) Hopper empty or low in coal (a) Fill the hopper to the proper level.
(b) Clinker obstructing the retort. (b) Remove clinker.
(c) Clogged smoke back connection. (c) Remove obstruction.
(d) Fire burning down in the retort. (d) Check air supply (fire may be getting too much) or rate of coal feed (may be too low).
Fire is out.
(a) Empty hopper. (a) Refill to proper level.
(b) Clinkers obstructing the retort. (b) Remove clinkers.
(c) Switch may be off. (c) Place in on position.
(d) Blown fuse. (d) Replace fuse.
(e) Tripped circuit breaker. (e) Reset circuit breaker.
(f) Failure in electric controls. (f) Contact manufacturer for a service call.

Troubleshooting Oil Burners

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Individuals involved in the installing and repairing of oil burners should be aware of a number of different indicators of malfunctions in the equipment, their probable causes, and some suggested remedies.

The average individual is most aware of malfunctions that warn the senses through excessive noise, smoke, or odor. These are external warning signals that require immediate investigation. Their nature is such that tracing the probable cause of the malfunction is made easier.

Excessive noise (pulsation, thumping, rumbling, etc.) in the heating unit is generally caused by a problem with the oil burner nozzle. It can usually be corrected by any one of the following methods:

• Replace the nozzle with one having a wider spray angle.
• Replace the nozzle with one having the next size smaller opening.
• Install a delayed-opening solenoid on the nozzle line (this reduces pulsation).

Sometimes a noisy fire is caused by cold oil originating from outside storage tanks. This noise may be greatly reduced or eliminated by pumping the fuel oil under 120 to 125 psi through the next size smaller nozzle.

Excessive smoke has a number of possible causes, including the
following:

• The air-handling parts of the oil burner may be too dirty to operate efficiently.
• The combustion chamber or burner tube may be damaged by burn-through or loose materials.
• The oil burner nozzle may be the wrong size.

The dirty air-handling parts (e.g., the fan blades, air intake, and air vanes in the combustion head) can be made to operate more efficiently by a thorough cleaning. If the excessive smoke is caused by the oil burner nozzle, this can be corrected by replacing the nozzle with one that is a size smaller or one having the next narrower spray angle. A damaged combustion chamber is a more difficult problem to correct than the other two. In any event, all leakage through the walls must be eliminated before the oil burner can be expected to operate efficiently.

Excessive odors can be caused by flue obstructions or poor chimney draft. If the draft over the fire is lower than 0.02 to 0.04, it is usually an indication that the problem lies with the flue or chimney draft. The cause is usually an obstruction in the flue or poor chimney draft. Other causes of excessive odor include the following:

• Delayed ignition
• Too much air through the burner

Delayed ignition is commonly traced to a problem with the electrodes. This condition can result from a variety of causes, including the following:

• Improper electrode setting
• Insulator cracks
• A coating of soot or oil on the electrode
• Incorrect pump pressure setting
• Incorrect spray pattern in the nozzle
• Clogged nozzle
• Air shutter open too far

Table 1-6 lists a number of recommended electrode settings that should eliminate delayed ignition if the electrode setting is the cause of the problem. The type of nozzle spray pattern can also result in delayed ignition. This is particularly true when using a hollow spray pattern in oil burners firing 2.00 gph and above. It can be corrected by replacing the nozzle with one having a solid spray pattern.

table 1 6 Troubleshooting Oil Burners

Table 1-7 lists a variety of problems encountered with oil burners, many of which are of an internal nature and require a great degree of experience and training to correct.

Table 1-7 Oil Burner Troubleshooting

Symptom and Possible Cause Possible Remedy
No heat—circulator (pump) off and burner running.
(a) Defective circulator. (a) Replace circulator.
(b) Defective thermostat. (b) Replace thermostat.
(c) Defective relay. (c) Replace relay.
(d) Defective aquastat. (d) Replace aquastat.
(e) Incorrect aquastat setting. (e) Reset aquastat.
(f) Loose or disconnected wiring. (f) Tighten or reconnect wiring.
(g) Defective zone valve. (g) Replace zone valve.
No heat—both circulator (pump) and burner running.
(a) Defective or loose circulator coupling. (a) Repair or replace.
(b) Broken circulator impeller. (b) Repair or replace circulator.
(c) Air trapped in lines. (c) Locate point of entry and repair; purge air from lines.
(d) Loose or disconnected wiring. (d) Tighten or reconnect wiring.
(e) Defective zone valve. (e) Replace zone valve.
(f) Frozen flow valve. (f) Repair or replace flow valve.
No oil flow at nozzle.
(a) Oil level below intake line in oil storage tank. (a) Fill tank with oil.
(b) Clogged strainer. (b) Remove and clean strainer.
(c) Clogged filter. (c) Replace filter element.
(d) Clogged nozzle. (d) Replace nozzle.
(e) Air leak in intake line. (e) Tighten all fittings in intake line; tighten unused intake port plug; check filter cover and gasket.
(f) Restricted intake line (high vacuum reading). (f) Replace any kinked tubing and check valves in intake line.
(g) Air-bound two-pipe system. (g) Check for and insert bypass plug. Make sure return line is
below oil level in tank.
(h) Air-bound single-pipe system. (h) Loosen gauge port plug or easyflow valve and bleed oil for
15 seconds after foam is gone in bleed hose. Check intake line fittings for tightness and tighten if necessary. Check all pump plugs for tightness and tighten if necessary.
(i) Slipping or broken coupling. (i) Tighten or replace coupling.
(j) Rotation of motor and fuel unit is not the same as indicated by arrow on pad at top of unit. (j) Install fuel unit with correct rotation.
(k) Frozen pump shaft. (k) Check for water and dirt in tank and correct as necessary;
return defective pump to manufacturer or service center for repair or to be replaced.
Noisy operation.
(a) Bad coupling alignment at fuel unit. (a) Loosen fuel unit mounting screws slightly and shift fuel unit in different positions until noise is eliminated. Retighten mounting screws.
(b) Air in inlet line. (b) Check all connections for damage. Replace as necessary. Use only good flare fittings.
(c) Tank hum on two-pipe system and inside tank. (c) Install return-line hum eliminator in return line.
Pulsating pressure.
(a) Partially clogged strainer. (a) Remove and clean strainer.
(b) Partially clogged filter. (b) Replace filter element.
(c) Air leak in intake line. (c) Tighten all fittings; replace damaged fittings and/or damaged intake line.
(d) Air leaking around strainer cover. (d) Check for loose cover screws and tighten securely. Check for damaged cover gasket and replace if necessary.
Low oil pressure.
(a) Defective gauge. (a) Replace defective gauge.
(b) Burner nozzle capacity is greater than fuel unit capacity. (b) Replace fuel pump with one of correct capacity.
Improper nozzle cutoff.
(a) Trapped air causing fuel pump operating problem. (a) Insert pressure gauge in nozzle port of fuel pump. Run burner. If burner shuts down after a minute of operation and
pressure drops from normal operating pressure and stabilizes, the fuel pump is running and the problem is with trapped air. Correct as necessary.
(b) Defective fuel pump. (b) Insert pressure gauge in nozzle port of fuel pump. Run burner. If burner shuts down after a minute of operation and
pressure drop is 0 psi, fuel pump is defective and should be replaced.
(c) Filter leaks. (c) Check face of cover and gasket for damage and repair or replace as necessary.
(d) Loose strainer cover. (d) Tighten strainer cover screws.
(e) Air pocket between cutoff valve and nozzle. (e) Run burner by stopping and starting unit until smoke and afterfire disappear.
(f) Partially clogged nozzle strainer. (f) Clean strainer or change nozzle.
(g) Leak in nozzle adapter. (g) Change nozzle and adapter.
Oil leak—oil leaking inside burner.
(a) Seal leaking. (a) Replace seal or pump.
(b) Blown seal in a single-pipe system. (b) Check to see if bypass plug has been left in fuel pump. Replace pump.
(c) Blown seal in a two-pipe system. (c) Check for kinked tubing or other obstructions in return line. Replace pump.
(d) Cracked nozzle adapter. (d) Replace nozzle adapter.
(e) Defective pump piston. (e) Replace pump.
(f) Loose fitting. (f) Tighten or replace fitting.
(g) Loose fuel unit cover. (g) Tighten cover screws.
(h) Loose plugs or fittings. (h) Dope with good-quality thread sealer; retighten plugs or fittings.
(i) Leak at pressure adjustment screw or nozzle plug caused by damaged washer or O-ring. (i) Replace washer or O-ring as necessary.
(j) Damaged gasket. (j) Replace gasket.
Oil leak—oil leaking on outside of burner.
(a) Loose fittings. (a) Tighten fittings.
(b) Defective fittings. (b) Replace fittings.
(c) Damaged gasket. (c) Replace gasket.
Burner running—no oil pumping into combustion chamber and no fire in chamber.
(a) No oil in storage tank. (a) Fill storage tank.
(b) Clogged fuel pump. (b) Repair or replace fuel pump.
(c) Defective fuel pump. (c) Replace fuel pump.
(d) Clogged nozzle. (d) Clean or replace nozzle.
(e) Damaged or defective nozzle. (e) Replace nozzle.
(f) Clogged filter. (f) Clean or replace.
(g) Obstructed oil line. (g) Remove obstruction or replace fuel line.
(h) Closed oil valve. (h) Repair or replace oil valve.
(i) Loose or defective oil pump coupling. (i) Tighten coupling or replace oil pump.
(j) Defective oil valve. (j) Replace valve.
(k) Lost prime. (k) Reestablish prime or replace pump.
Burner running—oil pumping into combustion chamber but no fire in chamber.
(a) Chamber obstructed. (a) Locate and remove obstruction.
(b) Too much air. (b) Adjust to proper level.
(c) Water contaminating the oil. (c) Locate point of contamination and repair; drain and replace oil.
(d) Defective or weak ignition transformer. (d) Replace ignition transformer.
(e) Dirty electrodes. (e) Clean electrodes.
(f) Cracked or broken electrodes. (f) Replace electrodes.
(g) Loose wires. (g) Tighten connection or replace wires.
(h) End cone obstruction. (h) Repair.
Smoky fire.
(a) Improper pump pressure. (a) Set proper pump pressure or replace defective pump.
(b) Incorrect nozzle. (b) Replace nozzle.
(c) Distorted and burnt end cone. (c) Replace.
(d)Water contaminating the oil. (d) Locate point of contamination and repair; drain and replace oil.
(e) Dirty boiler. (e) Clean boiler.
(f) Dirty fan. (f) Clean fan
(g) Defective combustion chamber. (g) Replace.
Burner fails to restart after resetting safety relay.
(a) Power off. (a) Restore electricity to burner.
(b) Defective burner motor. (b) Replace burner motor or burner.
(c) Defective fuel pump. (c) Replace fuel pump.
(d) Defective safety relay. (d) Replace safety relay.
(e) Defective on-off switch. (e) Replace switch.
(f) Tripped circuit breaker. (f) Reset circuit breaker; call electrician if problem continues.
(g) Blown fuse. (g) Replace fuse; call electrician if problem continues.
(h) Loose or disconnected wiring. (h) Reconnect wires and tighten wiring connections.
Flame pattern not centered.
(a) Improperly positioned burner. (a) Reposition burner.
(b) Contaminated fuel. (b) Locate source of contamination and repair; drain and replace fuel.
(c) Obstruction in combustion chamber. (c) Locate and remove obstruction.
Water leaking from boiler pressure relief valve with pressure under 30 psi.
(a) Defective pressure relief valve. (a) Replace pressure relief valve.
Water leaking from boiler pressure relief valve with pressure at 30 psi or greater.
(a) Defective feed valve. (a) Replace valve.
(b) Holes or cracks in coils. (b) Replace coils.
(c) Expansion tank full. (c) Correct as necessary.
(d)Water temperature above 210°F . (d) Reduce water temperature; replace valve.