Oil Furnace Not Working: The Reset Button Rule

By Ray Bennett · Updated 2 October 2026 · 6 min read · Checked against the maker’s manual

Oil Furnace Not Working: The Reset Button Rule

Short answer

Press the red reset button once. Not twice, and never three or four times, because every press squirts more oil into a chamber that is not lighting and a late light off on a flooded chamber is what soots a whole house. Here is the one press rule and the five free checks that come before it.

If you take one thing from this page, take this. The red reset button gets pressed once.

Not twice because the first one did not work, and never four or five times while you get colder and crosser. Every press feeds another shot of oil into a chamber that is already not lighting, and when it finally does light, all of it goes at once.

Before you start

What to carry: a torch and a screwdriver. Twenty minutes, and most of it is looking rather than doing.

Is this even your machine? An oil furnace has a tank, a pipe to a burner, and a motor that sounds like a jet when it fires. If you have a gas line, or an electric furnace with a thick cable and no flame at all, this is not your page: the free checks for a gas furnace.

Oil boilers behave the same way. The burner, the reset button and the rule about it are identical, even though the heat goes into water rather than air.

The one press rule, and why it exists. Press reset once. If it fires and stays lit, good. If it stops again, stop.

What the extra presses do. The nozzle sprays a fine mist of oil every time the burner tries. If it is not igniting, that oil pools in the combustion chamber. Press it enough times and you have a puddle sitting in there waiting for a spark.

What happens then is called a puff back. All of it lights at once, and the blast pushes soot and oily smoke out through the cabinet and into the ductwork. It coats every room in the house in a greasy black film that does not wash off, and it is a bill in the thousands. It can also start a fire.

And if you can smell smoke or oil in the house, or see soot anywhere, switch the furnace off at the emergency switch and open windows. Do not reset it to see what happens.

The five things to check before you press anything

Tank, switch, thermostat, breaker, filter. Four of the five are free and the fifth is the cheapest part on the machine.

Check 1Free, twenty minutes

Work down the list, in this order

1. How much oil is actually in the tank. Not what the gauge says. Float gauges stick, and a gauge stuck on a quarter full can hide an empty tank. Tap the gauge, and if you can, use a dipstick on the tank.

2. The switch that looks like a light switch. There is an emergency switch, usually at the top of the basement stairs and often with a red plate, and a second one on or beside the furnace. One of them gets knocked off, or switched off by somebody who thought it was the cellar light.

3. The thermostat. Set to Heat, set above room temperature, and with fresh batteries if it takes them: how to prove a thermostat is calling for heat.

4. The breaker. One for the furnace and sometimes a separate one for the oil pump.

5. When the filter and nozzle were last changed. They are annual items. If it is three years since anybody serviced it, that is your answer rather than a mystery.

It ran out of oil, and now it will not go

Check 2

What a refill after a run out actually needs

This one catches nearly everybody, because a full tank feels like the fix and the furnace stays dead.

Air is now in the line. A pump cannot push air, so the line has to be bled at the burner before it will fire again. That is a short job for somebody with the tools and it is why the furnace still does nothing after the delivery.

The tank bottom got stirred up. Years of sludge and water sit in the bottom of an oil tank. A delivery drops in with force and mixes the lot, and the filter and the nozzle take it straight afterwards.

So ask for the filter and the nozzle with the visit. A bleed on its own on a tank that just ran dry often means a second call out soon after.

Let it settle first. A wait after a delivery before firing gives the worst of it time to drop back down.

And fit a tank gauge you trust. Running one dry is expensive every single time, and it is entirely avoidable.

It fires, then stops after a few seconds

A burner that lights and dies a few seconds later is a different fault from one that never lights at all, and the eye that watches the flame is usually involved.

Check 3

Tell a light off fault from a flame sensing fault

It roars, you see flame, then it stops within 15 to 45 seconds, the lockout time Beckett and Honeywell give for their controls. The control is being told there is no flame even though there is. The part that watches is a small light sensitive eye called a cad cell, and soot on it blinds it. Cleaning it is minutes.

It roars and never lights at all. No fuel, or no spark. That is the filter, the nozzle, the pump or the electrodes.

It lights but the flame is lazy, yellow and smoky. Do not leave it running. That is incomplete combustion, it sends soot into the heat exchanger, and soot is what ruins one: what a failing heat exchanger actually means.

It runs fine then cuts out after twenty minutes, every time. Airflow, not oil. The limit is tripping because the heat cannot get away, and the filter is the first suspect: what a tripping limit is telling you.

It short cycles, on and off every few minutes. Often the same thing, sometimes the control. Either way it is wearing the machine out fast.

Questions people ask

I already pressed it five times. What now?

Leave it alone and get somebody out before it fires. Say on the phone how many times it was pressed, because that changes how they approach it and it is far better said than discovered.

Why does my reset button keep tripping?

It is not tripping, it is locking out, and it locks out because the burner was told to light and no flame was proved. Something in the chain from tank to nozzle to spark to cad cell is failing, and the button is the messenger.

Is the reset button the same as the one on the boiler in the cellar?

If it is an oil boiler, yes, and the same rule applies. There are other reset buttons on other machines that mean different things: which reset button you are actually looking at.

Can I bleed the line myself?

Mechanically it is a bleed screw and a jar. In practice you are working with the burner live, oil under pressure and a machine that is about to light, and the saving is one call out. It is the point where most people are better off paying.

How often does it really need servicing?

Once a year, genuinely, which is not true of every machine in the house. Oil burns dirtier than gas, so the filter, the nozzle and the chamber all need the attention: what each machine actually needs and how often.

There is a smell of oil but it seems to run fine.

Worth chasing rather than living with. A weeping filter, a loose fitting or a slightly rich burner all smell, and an oil smell that has been there for weeks is usually a leak somewhere with a tray under it.

Sources: Beckett GeniSys 7505 oil burner control manual (lockout time, resets, pump bleeding, puff-back, annual service), Resideo (Honeywell) R7184 instructions 69-1459-06 (limited reset, lockout time, cad cell) and Riello single stage oil burner manual C6505027 (yearly oil filter, lockout causes)