If you’ve run out of heating oil, order a delivery first, then don’t keep pressing the boiler’s reset button. When an oil boiler runs dry it usually locks out, and it may need air bled from the fuel line before it will fire again. Once the tank is filled, give it time to settle and try one reset. If it still won’t run, our boiler repairs team can get it going. It happens more often than people think in cold spells, especially in rural homes around Devizes and Calne where many homes rely on oil.
What happens when an oil boiler runs dry
An oil boiler draws kerosene from the tank through a feed pipe to the burner. When the level drops too low, the burner starts pulling in air instead of fuel. The flame fails, the boiler goes into lockout and a light or fault code usually appears.
Two other things can happen as the tank empties. The last few centimetres of oil often contain sludge and water that have settled over the years, and that debris can be drawn into the filter or the burner. Air can also get trapped in the fuel line, which stops the oil pump from priming properly.
What you can safely do yourself
These checks are fine for any homeowner:
- Check the tank level. Use the sight gauge or level monitor so you know for certain the tank is empty, and not something else such as a closed valve.
- Order oil. Tell your supplier you’ve run dry. Many suppliers offer emergency or smaller top-up deliveries, but availability varies in cold weather.
- Wait after the delivery. A fresh delivery stirs up anything sitting in the bottom of the tank. Leaving it for a while, often an hour or more, lets that settle before the boiler draws from it.
- Try one reset. Press the lockout reset button once and give the boiler a minute or two. If it locks out again, stop there.
Pressing reset over and over can flood the combustion chamber with oil, which makes the problem worse and can be unsafe.
Jobs to leave to an OFTEC registered engineer
Bleeding air from the fuel line, changing the oil filter, cleaning the burner and checking the pump all involve working on the boiler and fuel supply. An OFTEC registered engineer should do these. They’ll also check whether sludge has blocked the filter or nozzle, which is common after running dry.
If the tank keeps throwing up sludge or water, it may be worth a closer look at the tank itself. Our oil tank installations page explains what’s involved if it’s reaching the end of its life.
How to avoid running out again
- Check your level weekly in winter, more often during a cold snap.
- Reorder when the tank is about a quarter full, not when it’s nearly empty. Delivery times can stretch in December and January.
- Think about a remote level monitor that shows the level indoors or on your phone.
- Keep the area around the fill point clear so drivers can deliver easily.
- Book an annual oil boiler service so the filter and nozzle are cleaned and replaced before winter.
Oil-heated homes in Devizes, Calne and Warminster
Large parts of West Wiltshire sit off the gas network, so oil is the norm in villages and farmhouses outside the main towns. Homes along the edge of Salisbury Plain near Warminster and the countryside around Calne often have long drives and tanks tucked well away from the house, which makes it easy to forget to check the gauge. Bigger, older properties can also get through oil quickly when the weather turns, so a tank that lasted ages in October can empty fast in a frosty November.
Frequently asked questions
Will my oil boiler restart on its own after a delivery?
Sometimes. If air hasn’t got into the fuel line, the boiler may fire after a single reset. Often, though, the line needs bleeding or the filter is blocked with sludge from the bottom of the tank. If one reset doesn’t work, leave it and call an OFTEC registered engineer rather than pressing the button again and again.
How long should I wait after an oil delivery before using the boiler?
A fresh delivery disturbs any sediment and water in the tank. Waiting a while, often an hour or more, gives it time to settle so the boiler is less likely to draw debris into the filter. Your engineer or oil supplier may give you specific advice for your tank and system.
Can running out of oil damage my boiler?
It can cause problems. Sludge and water drawn from the bottom of the tank can block the filter, nozzle or pump, and repeated resets can flood the burner. Most of the time an engineer can clear it, but it’s far easier and cheaper to avoid running dry in the first place.
Ran out of oil and the boiler won’t fire?
Give us a call on 01225 708562 or drop us a message and we’ll come out, bleed the line, clear any sludge and get your heating back on.