Oil Furnace Not Working? The Do’s and Don’ts Until Help Arrives

Is your oil furnace not working on a cold night? Start with four quick checks: your oil tank level, the burner switch, the thermostat and the furnace itself. If the burner still won’t start, press the reset button once only and then call for help. Some no-heat problems are easy for a homeowner to fix. Others need a trained technician. While you wait, skip the shortcuts like ovens, candles and space heaters used as your main heat, because they can put your family at risk.

Start with the simple checks

Most no-heat calls begin with something small, so look at the basics before you assume the worst. Each of these checks takes a minute or two and needs no tools.

Check your oil tank level

An empty tank is one of the most common reasons an oil furnace stops running. Look at the gauge on top of your tank. It’s usually a small glass or plastic dome with a float inside. If the float is at or near the bottom, you’re likely out of fuel. Customers on automatic delivery have their tank filled for them, so they don’t need to watch the oil level. If you’re a will-call customer, you’ll need to call ahead and schedule a delivery, so check your gauge often during cold stretches.

Running out of oil can also mean more than refilling the tank. After a run-out, the burner may need to be primed and restarted before it will fire again. If your tank was empty and the heat doesn’t come back after a delivery, give us a call.

Make sure the burner switch is on

Oil burners have an emergency shutoff switch, often at the top of the basement stairs or near the furnace. In many homes it looks like a regular light switch with a red cover plate. Someone can easily flip it off by mistake, thinking it controls a light. Make sure the switch is in the on position. Also check your electrical panel for a tripped breaker on the furnace circuit.

Check your thermostat settings

Confirm the thermostat is set to heat and that the set temperature is above the current room temperature. On a forced air system, the fan should be set to auto. If your thermostat runs on batteries and the screen is blank or dim, replace them. Our guide to the ideal temperature for your home in winter can help you pick a comfortable setting once the heat is back on.

Look at the furnace itself

Once you know you have fuel, power and a call for heat, check the furnace. See whether it’s running and whether the cabinet feels warm. If the furnace is running and warm but little heat reaches the rooms, a dirty air filter may be blocking the flow of warm air. Pull out the filter and hold it up to a light. If you can’t see light through it, swap in a clean one of the same size.

If the furnace isn’t running at all, look for the reset button on the burner relay. The relay is usually a small box mounted on the burner, and the button is often red. Press it once only. Each press sends oil into the combustion chamber. If the burner doesn’t light, that unburned oil can collect, and it could start a fire when the burner finally does ignite. If one press doesn’t restart the furnace, leave it alone and call a technician.

What not to do while you wait

Staying warm until help arrives matters, but some common shortcuts cause more harm than a cold house. Here’s what to avoid.

Don’t let your oil run low

A low tank can cause problems even before it runs dry. When the oil level drops near the bottom, sediment build-up from the tank floor can get drawn into the fuel line and clog the oil filter. With fuel additives, sediment build-up is uncommon, but keeping your tank from running low is still the easiest way to avoid a no-heat call. Automatic delivery takes this worry off your list.

Don’t heat with space heaters, ovens or candles

Space heaters can add warmth to a drafty corner, but the Massachusetts Department of Fire Services warns they aren’t designed to replace a household heating system. They’re a frequent cause of accidental home fires in winter. If you use one briefly, keep it clear of curtains, bedding and furniture, and never leave it running unattended.

Never heat your home with a gas or electric oven. A gas oven left on for heat can burn poorly and release carbon monoxide, a gas you can’t see or smell. The EPA explains how carbon monoxide affects indoor air and why unvented gas appliances are a concern. Candles are a fire risk too, and careless candle use causes many home fires every year. Working carbon monoxide alarms on every level of your home are a must. Our post on carbon monoxide safety for heating season covers where to put them.

Keep a no-heat call from happening

Regular maintenance is the best way to keep your oil furnace running through the winter. During a regular tune-up, a technician inspects and cleans the burner, replaces the oil filter and nozzle, and checks that the system is burning fuel safely and efficiently. No system is perfect, and even a well-kept furnace can stop working. But regular maintenance catches many small problems before they leave you in the cold. For more ideas, read 4 ways to help avoid no-heat emergencies in Massachusetts.