Oil burner parts, found two ways: pick your burner below for a labeled exploded diagram with OEM part numbers and where to buy, or start from the symptom further down. Not sure which part does what? Start with how an oil furnace works. Installing burner parts and setting combustion is licensed-technician work; this page is for understanding the fix and sourcing the right part.
Some links on this page are affiliate links: as an Amazon Associate this site earns from qualifying purchases, and it may earn from other retail partners, at no extra cost to you. Parts shown are general references, not specific endorsements. Match any part to your unit's make, model, and spec before buying.
Know your burner? Jump straight to its labeled diagram and part numbers.
Find the exact Lynn replacement chamber kit for your boiler or furnace by brand and model.
Tools rather than parts? The technician's tools and gear page lists the kit by job, and the flare fittings page explains why oil lines are never joined with compression fittings.
A clogged filter, a starved or failing pump, air in the suction line, or sludge from a low tank. The burner tries but never gets a clean shot of oil.
Read more: Oil furnace not turning on? Work this list before you call , Ran out of heating oil? Here's the order of operations , How to bleed and prime an oil furnace after running out , Oil furnace blowing cold air: why, and what to check , Water in your oil tank: how it gets there and what to do
A sheet of oil-only sorbent laid under the burner, filter, and pump. It catches the drips from a filter change, a bleed, or a weeping fitting before they soak into the floor and leave the boiler room smelling of oil.
Replace it when: Whenever a pad is saturated or you can smell oil near the burner. Put a fresh one down before a filter change or a bleed, and keep a pack on the shelf.
Catches sludge and water before they reach the pump and nozzle. The cartridge is a routine wear item changed at every tune-up.
Replace it when: Every tune-up, after a run-out, or whenever the burner starves for fuel.
Often replaced at the same visit: nozzle, pump strainer (in the tune-up kit), oil safety valve
Common: General 1A-25 cartridge, General 2A-700 spin-on
Oil filter and cartridge: how it works and what to buy →
Pulls oil from the tank and pressurizes it to the nozzle.
Replace it when: No or low fuel pressure, the pump will not prime, or it leaks at the shaft.
Often replaced at the same visit: pump coupling, nozzle, nozzle line
Common: Suntec A and B series, Webster
Purges air from the oil line so a one-pipe system self-bleeds after a run-out instead of locking out on air.
Replace it when: Repeated air-in-line lockouts, especially after the tank has run dry.
Often replaced at the same visit: flex oil lines
Fuel oil de-aerator: how it works and what to buy →
A fuel shutoff with a fusible link that closes the oil line automatically in a fire.
Replace it when: It sticks, leaks, or its fusible link has tripped.
Often replaced at the same visit: oil filter, nozzle, pump strainer (in the tune-up kit)
Fusible oil safety valve: how it works and what to buy →
Spins the fuel pump and the combustion-air fan on the burner.
Replace it when: The motor hums but will not start, runs hot or noisy, or trips on its reset.
Often replaced at the same visit: nozzle, pump strainer (in the tune-up kit), pump coupling
An additive that disperses water, controls sludge, and inhibits the microbes that grow at the oil and water line in a tank.
Replace it when: Seasonally, or when sludge or water has been a known problem in the tank.
Oil is arriving but nothing lights it: worn or mis-gapped electrodes, a cracked porcelain insulator, or a weak igniter or transformer.
Read more: Oil furnace not turning on? Work this list before you call , Oil furnace reset button: when to press it (just once)
The pair of ceramic-insulated rods that arc a high-voltage spark to light the oil spray.
Replace it when: Weak or no spark, a cracked porcelain insulator, or as part of a tune-up.
Often replaced at the same visit: nozzle
Steps house voltage up to roughly 10,000 volts to fire the electrodes. Newer burners use a solid-state igniter in the same role.
Replace it when: No spark at the electrodes when the electrodes and gap are good.
Often replaced at the same visit: nozzle, cad cell, pump strainer (in the tune-up kit)
The brain on the burner: it runs the ignition sequence, watches the cad cell, and latches into lockout on a failed start.
Replace it when: Erratic lockouts, no ignition sequence at all, or failed flame-detection tests after the cad cell and wiring check out.
Often replaced at the same visit: nozzle, pump strainer (in the tune-up kit), cad cell
Common: Beckett GeniSys 7505, Honeywell/Resideo R7184, Honeywell R8184
The burner lights but the cad cell cannot confirm it, so the primary control shuts down. Usually a sooted or mispositioned cad cell, or a flame-quality problem behind it.
Read more: Furnace fires then shuts off: oil burner flame failure , Oil furnace reset button: when to press it (just once) , Oil furnace blowing cold air: why, and what to check
Atomizes the oil into a fine spray for combustion. It is sized by flow rate (GPH), spray angle, and pattern, so the replacement has to match the burner's spec exactly.
Replace it when: Every tune-up, and any time the flame is sooty or smoky or the burner will not light cleanly.
Often replaced at the same visit: pump strainer (in the tune-up kit), oil filter, cad cell
The light-sensing eye that proves a flame is present. If it cannot see flame fast enough, the primary control locks the burner out.
Replace it when: The burner locks out even with a visible flame, or the cell face is sooted or cloudy.
Often replaced at the same visit: nozzle, pump strainer (in the tune-up kit), primary control
The brain on the burner: it runs the ignition sequence, watches the cad cell, and latches into lockout on a failed start.
Replace it when: Erratic lockouts, no ignition sequence at all, or failed flame-detection tests after the cad cell and wiring check out.
Often replaced at the same visit: nozzle, pump strainer (in the tune-up kit), cad cell
Common: Beckett GeniSys 7505, Honeywell/Resideo R7184, Honeywell R8184
Spins the fuel pump and the combustion-air fan on the burner.
Replace it when: The motor hums but will not start, runs hot or noisy, or trips on its reset.
Often replaced at the same visit: nozzle, pump strainer (in the tune-up kit), pump coupling
Sounds when carbon monoxide builds up. Every oil-heated home should have one on each level and one near the boiler room, because a sooted chamber, a blocked flue, or a puffback can put CO into the house before anyone smells oil.
Replace it when: When it chirps end-of-life (sensors last 7 to 10 years), if it is older than the date printed on the back, or if the house has none.
A run-out pulls air and tank sludge into the line. Bleeding, a fresh filter, and sometimes a de-aerator are what get it running again. Wondering about a stopgap fuel? Read can you put diesel or kerosene in an oil tank.
Read more: Ran out of heating oil? Here's the order of operations , How to bleed and prime an oil furnace after running out , What is Bioheat fuel? B5, B10, B20, and B100 explained
A sheet of oil-only sorbent laid under the burner, filter, and pump. It catches the drips from a filter change, a bleed, or a weeping fitting before they soak into the floor and leave the boiler room smelling of oil.
Replace it when: Whenever a pad is saturated or you can smell oil near the burner. Put a fresh one down before a filter change or a bleed, and keep a pack on the shelf.
Catches sludge and water before they reach the pump and nozzle. The cartridge is a routine wear item changed at every tune-up.
Replace it when: Every tune-up, after a run-out, or whenever the burner starves for fuel.
Often replaced at the same visit: nozzle, pump strainer (in the tune-up kit), oil safety valve
Common: General 1A-25 cartridge, General 2A-700 spin-on
Oil filter and cartridge: how it works and what to buy →
Purges air from the oil line so a one-pipe system self-bleeds after a run-out instead of locking out on air.
Replace it when: Repeated air-in-line lockouts, especially after the tank has run dry.
Often replaced at the same visit: flex oil lines
Fuel oil de-aerator: how it works and what to buy →
The flexible flare-ended lines that connect the burner (or a de-aerator) to the rigid oil line, so the burner can be swung open for service without unmaking fittings.
Replace it when: Cracked, stiff, kinked or weeping, and whenever the burner is repiped for a de-aerator.
Often replaced at the same visit: de-aerator
The dial on top of the tank that shows the oil level on a float.
Replace it when: It sticks, fogs over, or reads the same no matter the level (do not trust a stuck gauge before a fill).
Any strong oil smell, smoke, or soot is a stop-and-call situation first, because of the carbon-monoxide and puffback risk. These are the parts a technician most often corrects once it is safe.
Read more: Oil furnace smells: is an oil smell in the house dangerous?
Atomizes the oil into a fine spray for combustion. It is sized by flow rate (GPH), spray angle, and pattern, so the replacement has to match the burner's spec exactly.
Replace it when: Every tune-up, and any time the flame is sooty or smoky or the burner will not light cleanly.
Often replaced at the same visit: pump strainer (in the tune-up kit), oil filter, cad cell
The hinged flue damper that stabilizes draft over the burner. Set wrong or stuck, it shows up as soot or odor.
Replace it when: It is stuck, rattling, or the wrong size after a flue change.
Often replaced at the same visit: nozzle
Barometric draft damper: how it works and what to buy →
Sounds when carbon monoxide builds up. Every oil-heated home should have one on each level and one near the boiler room, because a sooted chamber, a blocked flue, or a puffback can put CO into the house before anyone smells oil.
Replace it when: When it chirps end-of-life (sensors last 7 to 10 years), if it is older than the date printed on the back, or if the house has none.
The fittings on the tank itself: the gauge you read before a fill, the whistle that prevents an overfill, and the caps that keep water out.
Read more: How to read an oil tank gauge (and why a stick beats it) , Water in your oil tank: how it gets there and what to do , Oil tank replacement cost: price and when a tank is done
The dial on top of the tank that shows the oil level on a float.
Replace it when: It sticks, fogs over, or reads the same no matter the level (do not trust a stuck gauge before a fill).
The vent fitting that whistles while the tank fills and goes silent when it is full, so a delivery does not overfill.
Replace it when: It stopped whistling on the last fill. A no-whistle fill risks an overfill and spill.
Caps that seal the fill and vent pipes so water and debris stay out of the tank.
Replace it when: A cap is missing, cracked, or no longer sealing (water in the tank breeds sludge).
Water, sludge, and cold-weather gelling start in the tank. These are the consumables that keep the fuel clean before it reaches the filter and the nozzle.
Read more: What is Bioheat fuel? B5, B10, B20, and B100 explained , Water in your oil tank: how it gets there and what to do , Heating oil vs diesel vs kerosene: is it the same fuel?
Catches sludge and water before they reach the pump and nozzle. The cartridge is a routine wear item changed at every tune-up.
Replace it when: Every tune-up, after a run-out, or whenever the burner starves for fuel.
Often replaced at the same visit: nozzle, pump strainer (in the tune-up kit), oil safety valve
Common: General 1A-25 cartridge, General 2A-700 spin-on
Oil filter and cartridge: how it works and what to buy →
An additive that disperses water, controls sludge, and inhibits the microbes that grow at the oil and water line in a tank.
Replace it when: Seasonally, or when sludge or water has been a known problem in the tank.
A paste smeared on the bottom of the gauge stick before you dip the tank. It changes color exactly where it touched water, so you read the water depth separately from the oil above it.
Replace it when: Use it whenever water is the suspect: a filter that keeps loading up, sludge, or a burner that starves after a delivery. A trace is common and managed with treatment; more than a trace, or water that keeps coming back, means the tank needs pumping and cleaning.
A winter treatment that lowers the temperature at which heating oil or a biodiesel blend gels, so the fuel keeps flowing through the line and the filter in a cold snap.
Replace it when: Before cold weather, while the fuel is still clear: an additive cannot dissolve wax that has already formed, so it has to be in the tank before the fuel reaches its cloud point. Outdoor above-ground tanks are the ones at risk; indoor and buried tanks are buffered and rarely need it.
The wear parts a yearly tune-up replaces before they fail mid-winter. Replacing these on a schedule is what keeps the lockouts on this page rare.
Read more: Oil furnace maintenance: tune-up checklist and cost , How long do oil furnaces last? Lifespan and warning signs
A sheet of oil-only sorbent laid under the burner, filter, and pump. It catches the drips from a filter change, a bleed, or a weeping fitting before they soak into the floor and leave the boiler room smelling of oil.
Replace it when: Whenever a pad is saturated or you can smell oil near the burner. Put a fresh one down before a filter change or a bleed, and keep a pack on the shelf.
Atomizes the oil into a fine spray for combustion. It is sized by flow rate (GPH), spray angle, and pattern, so the replacement has to match the burner's spec exactly.
Replace it when: Every tune-up, and any time the flame is sooty or smoky or the burner will not light cleanly.
Often replaced at the same visit: pump strainer (in the tune-up kit), oil filter, cad cell
The pair of ceramic-insulated rods that arc a high-voltage spark to light the oil spray.
Replace it when: Weak or no spark, a cracked porcelain insulator, or as part of a tune-up.
Often replaced at the same visit: nozzle
Catches sludge and water before they reach the pump and nozzle. The cartridge is a routine wear item changed at every tune-up.
Replace it when: Every tune-up, after a run-out, or whenever the burner starves for fuel.
Often replaced at the same visit: nozzle, pump strainer (in the tune-up kit), oil safety valve
Common: General 1A-25 cartridge, General 2A-700 spin-on
Oil filter and cartridge: how it works and what to buy →
The flexible flare-ended lines that connect the burner (or a de-aerator) to the rigid oil line, so the burner can be swung open for service without unmaking fittings.
Replace it when: Cracked, stiff, kinked or weeping, and whenever the burner is repiped for a de-aerator.
Often replaced at the same visit: de-aerator
A fuel shutoff with a fusible link that closes the oil line automatically in a fire.
Replace it when: It sticks, leaks, or its fusible link has tripped.
Often replaced at the same visit: oil filter, nozzle, pump strainer (in the tune-up kit)
Fusible oil safety valve: how it works and what to buy →
On a boiler, the control that sets the high limit and runs the circulator from the water temperature.
Replace it when: Overheating, the circulator will not run, or wild temperature swings.
Common: Honeywell/Resideo L8148, Honeywell L8124
On a hot-water boiler, moves heated water out to the baseboard or radiators.
Replace it when: The burner fires but heat never reaches the rooms, or the pump is noisy or seized.
An additive that disperses water, controls sludge, and inhibits the microbes that grow at the oil and water line in a tank.
Replace it when: Seasonally, or when sludge or water has been a known problem in the tank.
On a warm-air oil furnace (not a boiler), the return-air filter that keeps the blower and heat exchanger clean.
Replace it when: Monthly to quarterly through the heating season, sooner if it looks loaded.
The annual wear set a tune-up replaces together: nozzle, oil filter cartridge, cad cell, electrodes, and pump strainer gasket.
Replace it when: Once a year, before the heating season starts.
Often replaced at the same visit: nozzle, oil filter, primary control
The hinged flue damper that stabilizes draft over the burner. Set wrong or stuck, it shows up as soot or odor.
Replace it when: It is stuck, rattling, or the wrong size after a flue change.
Often replaced at the same visit: nozzle
Barometric draft damper: how it works and what to buy →
The refractory liner that holds combustion heat and protects the chamber walls.
Replace it when: When it is cracked, slumped, or crumbling, which a tech catches during a tune-up.
Find your exact chamber by boiler model →
See the upgrades and components guides for de-aerators, filters, dampers, and fire valves.
Parts and brands listed are the common, widely available ones for residential oil heat. Price figures are rough estimates, not live prices, and the exact part has to match your unit's make, model, and spec. Shopping links are affiliate links. The "Often replaced at the same visit" lines come from aggregate service records (counts of what was replaced on the same visit, nothing more) and are a prompt to check the neighboring part, not a rule.
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