This page covers the burner faults that lock oil units out, the tank and fuel-supply issues that cause half of all no-heat oil calls, and what the South Shore climate does to outdoor fuel equipment.
General inquiries: 7 AM–7 PM · Emergency calls: 24/7 · (888) 766-1474
Fuel type varies by property. Check whether the boiler uses gas, oil, propane, or electricity before calling; the fuel source affects the appropriate diagnostic steps.
The equipment reflects the housing: above-ground outdoor tanks behind capes and ranches where basements are finished or tight, and basement 275s in older homes and Victorians. Outdoor tanks live in salt air — legs rust, fittings corrode, and exposed fuel lines take the full force of January cold. Basement tanks live in damp — condensation forms inside a half-empty tank, and water sinks to the bottom of the fuel where the pickup lives.
That is why oil diagnosis in Marshfield starts at the tank, not the burner. The triage call will ask about the gauge level, whether the tank is above-ground or in the basement, when the filter was last changed, and whether the unit ran out recently — because fuel-supply faults cause a huge share of oil no-heat calls, and they are the cheapest to rule out. A burner cannot fire on fuel that is not arriving cleanly.
The components that actually fail on oil units.
Half the oil story happens before the burner.
Above-ground outdoor tanks near the shore are the hardest-working fuel equipment in town. Salt air attacks the legs and seams; a tank that looks fine from the driveway can have soft spots at the bottom seam where water collected. Surface rust on the shell is cosmetic — soft spots, weeping seams, or legs that flex under load are replacement signals, and they are worth having assessed before heating season, not during it.
Basement tanks have their own failure mode: condensation. A half-empty 275 in a damp Marshfield basement sweats inside, and water sinks to the fuel pickup. The result is a burner that sputters and locks out on water, not a lack of oil. Keeping the tank reasonably full through the season and changing the filter yearly are the two cheapest insurance policies an oil homeowner has.
Storm exposure ties it together. Nor'easters bring the deliveries to a halt and knock out power — and oil burners need electricity. An empty or near-empty tank going into a storm week is the most preventable no-heat call in Marshfield. Check the gauge before the forecast turns.
Oil burners wear on a schedule — service matches it.
An oil burner is a mechanical device with wearing parts, and the service schedule reflects that: yearly, before heating season — nozzle and filter replacement, electrode setting, chamber cleaning, and a combustion check with real instruments. The homes that skip a year are the ones that lock out in January, and the ones that skip two are the ones sooting up the chamber while they pay for it in fuel bills.
On the water side, the same sealed-system rules apply as anywhere: watch the gauge for a healthy 12–15 psi cold reading, and treat slow pressure loss as an expansion-tank or fitting question, not an oil question. If diagnosis shows the block itself is finished — weeping sections, a chamber that will not stay clean, efficiency stuck in the 70s — the installation and replacement page walks through staying with oil or switching fuels for your street.
Straight answers before you call.
The usual suspects are a worn nozzle, tired electrodes, a clogged filter straining the pump, or a weak ignition transformer — in that rough order of frequency. A proper service checks the fuel path and the ignition sequence together, because the two interact; a fuel-starved burner and a weak spark look alike at the lockout light.
Do not just hit reset. A run-out pulls sediment and air into the line, so the filter and nozzle may need attention and the line may need bleeding. Describe the run-out on the call — a pro restart after an empty tank is a standard service, and one blind reset often is not enough.
Rust on the legs and seams of an outdoor tank in salt air is the warning, not the failure — but it is the warning that matters. Surface rust on the shell is cosmetic; soft spots, weeping seams, or legs that flex are replacement signals. A pro can assess it on a service visit before it becomes a leak.
Fast sooting usually means the burner is not atomizing fuel cleanly — a worn nozzle, wrong pump pressure, poor draft, or a chamber that has never been properly cleaned. Soot wastes fuel and insulates the heat exchanger, so it shows up as climbing bills before it shows up as a lockout.
Only where piped gas actually reaches the property — the gas main has to be in the street, not just in town. The replacement page walks through the fuel-choice math; mention your street and the triage can tell you whether gas is even an option at your address.
Yearly, before heating season: nozzle and filter replacement, electrode setting, chamber cleaning, and a combustion check. Oil burners are mechanical and wear on a schedule — the homes that skip a year are the ones that lock out in January.
National guides that apply to oil systems here.
Nationally, oil boiler repair covers burner and fuel-path faults in general terms. If your unit is a sealed system losing pressure, the boiler pressure guide explains the healthy 12–15 psi cold reading, and boiler leak and pressure repair covers the fault behind it. Watching for the early warnings? Signs your boiler may need repair tells you what to notice. On gas instead — or thinking about switching? Gas boiler repair covers the piped-gas side of Marshfield, and a dead unit tonight belongs on emergency boiler repair.
Call (888) 766-1474 — mention your tank setup and the symptom, and get connected to a local pro.
