It’s a cold morning, the radiators are stone cold and the tank gauge is sitting on empty. If you’ve run out of heating oil, order a delivery first, then switch the boiler off so it doesn’t keep trying to fire. Once oil arrives, wait before restarting. If the boiler won’t fire or locks out, call us on 01865 602 994, as air may have been drawn into the supply line. You can also book a visit through our services page for help across Oxfordshire.
Step 1: Get oil on order
Call your usual supplier and ask about their quickest delivery option. Many offer smaller emergency top-ups at short notice, often at a higher price per litre. In a cold snap, delivery times can stretch, so the sooner you call, the better.
Step 2: Switch the boiler off
Turn the boiler off at the programmer or switch. Leaving it on means it keeps trying to fire with no oil, which can lead to repeated lockouts.
Don’t keep pressing the reset button. Repeated resets on an oil boiler can allow unburnt oil to build up in the combustion chamber, which creates a risk when it does fire. Most manufacturers warn against resetting more than a set number of times.
Step 3: Wait after the delivery
When the tank has been filled, give it time to settle before restarting. The delivery stirs up sludge and water from the bottom of the tank, and you don’t want that drawn straight into the filter. Your supplier or technician can advise how long to wait.
Step 4: Try the boiler once
Switch the boiler back on and let it try to fire. Some will start normally. Many won’t, because running dry pulls air into the oil line and the pump can’t push air.
If it locks out, press reset once only, as the manual describes. If it locks out again, stop there.
Why an engineer may need to visit
Getting an oil boiler going after it’s run dry often involves:
- Bleeding air from the oil pump and supply line
- Checking or changing the oil filter, which may have picked up sludge
- Checking the nozzle and burner for any damage from running dry
- Making sure the boiler fires cleanly and the combustion is right
This involves the fuel supply and burner, so it should be done by a competent oil technician, ideally OFTEC registered.
Keeping warm while you wait
- Use portable electric heaters safely, keeping them away from curtains and furniture
- Close internal doors to hold heat in the rooms you’re using
- Don’t use outdoor heaters, barbecues or camping stoves indoors, as they produce carbon monoxide
- If you have an immersion heater, it can provide hot water in the meantime
How to avoid running out again
- Check the gauge regularly through autumn and winter, and more often in cold spells
- Order early. Many people reorder at around a quarter full, rather than waiting until it’s nearly empty
- Don’t trust an old gauge. Sight gauges and floats can stick, so a dipstick or a remote monitor may give a better reading
- Watch for sudden drops. Unexplained loss could mean a leak or theft
- Book an annual service so the filter and supply line are checked
Off-grid homes around Oxfordshire
Many villages around Witney, Thame, Bicester and Princes Risborough rely on heating oil, and a delivery can take longer when every home on the round is ordering at once. Keeping an eye on the tank through October and November saves a cold wait later. If your boiler is old and keeps giving trouble, our oil boiler installation page covers replacement options.
Frequently asked questions
Why won’t my oil boiler start after a delivery?
Usually because air has got into the oil line after the tank ran dry. The pump can’t push air, so the burner won’t get oil and the boiler locks out. Sludge stirred up during delivery can also block the filter. Both need a technician to bleed the line and check the filter, rather than repeated resets.
How many times can I reset an oil boiler?
Check your boiler manual, but most manufacturers advise only one or two attempts. Each failed start can leave unburnt oil in the combustion chamber, which is a safety concern. If the boiler locks out again after a single reset, leave it off and call a qualified oil technician to find out why.
Can running out of oil damage the boiler?
It can cause problems. Sludge and water from the bottom of the tank can be drawn into the filter and pump, and air in the line causes lockouts. In most cases, bleeding the line and changing the filter sorts it, but it’s worth having the burner checked properly before relying on it.
Boiler still won’t fire?
If you’ve had oil delivered and the boiler still won’t start, give us a call on 01865 602 994 or drop us a message and we’ll get someone out to get your heating back on.
