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CARBON MONOXIDE - CO
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DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DIRECT VENTS / SIDE WALL VENTS
DRAFT REGULATORS, DAMPERS, BOOSTERS
DUCT SYSTEM & DUCT DEFECTS
ELECTRIC MOTOR DIAGNOSTIC GUIDE
FAN, AIR HANDLER BLOWER UNIT
FLOODED HEATING EQUIPMENT REPAIR
FLUE SIZE SPECIFICATIONS
GAS BURNER Flame & Noise Defects
GAS PIPING, VALVES, CONTROLS
GEOTHERMAL HEATING SYSTEMS
HEAT PUMPS, DIAGNOSIS, REPAIR
HEATING COST SAVINGS METHODS
HEATING OIL PIPING TROUBLES
HEATING OIL TANKS
HEATING SYSTEM NOISES
HEATING SYSTEM TYPES
GAS LP & NATURAL GAS SAFETY HAZARDS
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
MOTOR OVERLOAD RESET SWITCH
NOISE, HEATING SYSTEMS
ODORS FROM HEATING SYSTEMS
OIL FILTERS on HEATING EQUIPMENT
OIL FILL PIPE LEAKS
OIL SPILL CLEANUP / PREVENTION
PLASTIC Plexvent / Ultravent RECALL
PUFFBACKS, OIL BURNER
RELIEF VALVE LEAKS
Reset Switch - Heater Primary Control
RESET SWITCH - ELECTRIC MOTOR
Reset Switch - Stack Relays
SAFETY, HEATING INSPECTION
SAFETY RECALLS CHIMNEYS VENTS HEATERS
SOLAR HEATING SYSTEM DESIGNS
SOOT on OIL FIRED HEATING EQUIPMENT
STEAM HEATING SYSTEMS
THERMOSTATS, HEATING / COOLING
VIDEO GUIDES: Heating System Videos
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
ZONE VALVES, HEATING
How to inspect, diagnose & repair oil burners used on oil-fired heating boilers or furnaces using a visual inspection approach as well as (optional) simple test equipment. We include a description of common oil burner adjustment and operating problems and we illustrate some of the basic oil burner tests and measurements made in servicing and adjusting the equipment for safe, efficient operation. We illustrate oil burner smoke testing and oil burner carbon dioxide level measurement.
This article series answers most questions about all types of heating system troubleshooting, inspection, diagnosis, and repairs. We describe how to inspect, troubleshoot and repair heating and air conditioning systems to inform home owners, buyers, and home inspectors and students of heating service methods about common heating system defects. The articles at this website describe how to recognize common oil-fired heating appliance operating or safety defects, and how to save money on home heating costs
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In the oil burner inspection article provided here we explain visual and other clues of oil burner problems.
An expert inspection of an oil burner begins either with having made note of building owner/occupant concerns (noises, odors, no heat, high fuel costs), or with having made some basic visual observations outside: a sooty chimney top, for example. The sketch is courtesy of Carson Dunlop Associates. )
The oil burner inspection continues indoors, even before entering the utility room where the oil burner (or often more than one of them if oil fuel is used for both heating and a separate water heater) is located: look at the building interior as you enter: are there odors, soot deposits, noises associated with the heating system?
The oil burner inspection becomes detailed, and diagnostic, when you can actually see the equipment. It's obvious that you should notice oil leaks, soot in the boiler or furnace room, noises, odors, signs of repeated repairs, piles of junked parts, signs of unprofessional work (covers off of controls, sloppy wiring or plumbing). But just what each of these clues might mean bears some additional explanation that we offer below.
If the chimney top is sooty we don't yet know the cause of poor oil burner operation but we know there is a problem. If your inspection of the chimney top, even from ground level, perhaps with binoculars, shows water, frost, or mechanical damage to the chimney itself, or a missing chimney cap, these conditions may not only affect the operation of the oil burner, but they may be very unsafe. See CHIMNEY INSPECTION DIAGNOSIS REPAIR.
On entering the building or by customer interview, start with a check for these signs of improper oil burner operation, regardless of whether the burner is powering a boiler, furnace, or water heater:
We mentioned outdoor oil tank problems above, but even indoors you may spot signs of trouble that affect oil burner operation.
While it was possible to "eyeball" older oil fired equipment (spit on the flue for temperature and blow cigarette smoke at the burner for draft), modern oil fired equipment requires more accurate measurement and adjustment for good operation.
The Guide also includes this chart of oil fired heating system efficiency at different CO2 levels and stack temperatures.
The little hole we describe is where the service tech inserts test equipment to measure stack temperature, smoke level, and CO level. Some tech's use two holes to permit more than one measurement simultaneously. No hole = never measured. (Or new flue vent connector parts have just been installed on older equipment and no one has made a hole yet.)
Our photo (left) shows a Bachrach stack temperature measurement being made "in the breech" above a troublesome oil burner and boiler installation.
Watch out: don't record the stack temperature before the oil-fired heating system has been running for five minutes or so - you want to be sure the system has reached its stable and "normal" operating temperature.
Waiting a few minutes at this boiler we saw the flue temperature rise to 600 °F. At 600 °F. this heating system was left running a bit "hot" by the service tech. Why? Because a too-short chimney meant the system had a history of inadequate draft, sooting, backpressure, puffbacks, and loss of heat. This "fix" was a band-aid that kept the system running longer between (frequent) service calls, but at the expense of higher heating bills and wasted fuel.
We could have addressed this short chimney with a draft inducer fan, but a taller flue would be smart anyway, to get the chimney top higher than the roof surface. We discuss examples of extending chimney height to improve draft, performance, and fire safety separately at CHIMNEY HEIGHT EXTENSIONS. We discuss draft inducer or "draft boosting" fans for heating systems (and maybe for some fireplaces) in detail at DRAFT INDUCER FANS.
Just how short is "too short" for a chimney is a problem along with roof clearance requirements discussed at Chimney Height & Clearance
See BOILER OPERATING STEPS, 39 steps in how a heating boiler works. The following oil burner noise clues are taken from our more complete article: OIL BURNER NOISE SMOKE ODORS. Also see COMPLETE COMBUSTION, Stoichiometric for an explanation of complete fuel combustion and boiler or furnace maximum efficiency.
The basic measurements made by any competent oil heat service technician include the stack temperature, draft, smoke level, and carbon dioxide level. These data tell us whether or not the equipment is properly adjusted and operating safely and economically.
One of these most basic tests performed by an oil heat service technician is the "smoke test" using a strip of filter paper and a pump to sample the oil burner exhaust, measuring the level of smoke in the exhaust.
Details of how to measure the oil burner smoke level, a key measure used in setting the combustion air level, are now at OIL BURNER SMOKE TEST
Our photo (above left) shows a traditional smoke testing pump (the black cylinder with a handle at its right end) used for decades. This equipment was produced by Bachrach, an oil burner test equipment manufacturer.
The second common test performed by an oil heat technician evaluates the oil burner efficiency by measuring the carbon dioxide level or CO2 level in the oil burner exhaust. While there are electronic sensors used by some technicians for this purpose, many oil heat service tech's continue to use the time-tested Bachrach Fyrite™ oil burner tester.
Details of measuring the carbon dioxide level for oil burners, a second key measurement needed for proper setting of oil burner combustion air & operating temperature are now at OIL BURNER CO2 TEST
We look for obvious trouble signs before making any changes or adjustments to the oil burner assembly by turning off power to the equipment, shutting off the oil supply line at the closest service valve, and opening the oil burner for inspection.
Our sketch (left) shows how an oil burner gun atomizes and sprays heating oil into the combustion chamber - Audel Oil Burner Guide
Most oil burners are opened by loosening two screw clamps at the front of the transformer box mounted atop the oil burner tube and folding the hinged transformer back to expose the interior of the tube, the oil burner nozzle assembly, and other parts. Some obvious trouble signs inside the oil burner include:
This topic has moved. Now at OIL BURNER WONT RUN we have collected oil burner diagnostic procedures from several texts,  -  adapted, expanded, and generally re-ordered steps in order of most likely to be successful and easiest to perform.
Readers needing an approach to heating system inspections that assures thoroughness, should also see HEATING SYSTEM INSPECTION PROCEDURE where we explain an organized approach to inspecting the entire heating system, beginning outdoors, continuing indoors, and ultimately in most detail in the boiler or furnace room.
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Frequently Asked Questions (FAQs)
Question: my oil burner shuts down after just a few seconds
My oil burner will come on for a few seconds and then shut down. I have changed the control, and the cad cell. If I disconnect the cad cell start the burner and allow it to run for about 10 or 15 seconds and reconnect the cad cell it will usually continue running until the water is hot. Sometimes the burner will operate normally for a period of time.
If it sets overnight when heat is called for it will shut down after it starts as if it has no flame. I know the fire is there because I can hear it burning. If I connect my multi-meter to the cad cell the resistance goes from very high to about 400-500 ohms. The only thing I haven't done is check the cut-off solenoid because I don't know how. Thank you for any help you can give me. - R.M. 2/25/2014
Reply: try this oil burner diagnostic flowchart
A competent onsite inspection by an expert usually finds additional clues that would permit a more accurate, complete, and authoritative answer than we can give by email alone. You will find additional depth and detail in articles at our website.
That said, try this diagnostic routine to see if that helps. OIL BURNER WONT RUN - Diagnostic Steps - what to check in what order
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