Oil boiler repair in Scotland
Oil boilers fail differently from gas ones, and lockouts, nozzle problems and contaminated fuel account for most of the calls we take. We are OFTEC registered and cover oil breakdowns across East Lothian, Midlothian and Midlothian.
Gas Safe
OFTECOFTEC oil boiler repairs
When an oil boiler locks out or will not fire, our OFTEC registered engineers find the fault fast. We repair oil boilers across Scotland, including East Lothian, Midlothian and Midlothian, with emergency cover for no-heat jobs.
Boiler will not fire
The most frequent call we take on oil. Usually the nozzle, the photocell, the pump or an air lock in the supply line rather than the boiler itself.
Lockouts that will not reset
A boiler that locks out repeatedly is protecting itself from a fault that has not gone away. Resetting it over and over will not fix the underlying cause.
Fuel and tank problems
Water and sludge in the tank block filters and ruin nozzles. If the fuel is the problem, replacing boiler parts will only buy you a few weeks.
How it works
Call us
Tell us what the boiler is doing and whether it is locking out. That usually narrows the cause before we set off.
Diagnose the fuel path
We check the burner, the supply line and the tank, because on oil the fault often sits outside the appliance.
Agree the work
You get a clear explanation of what has failed and what the options are before anything is done.
Repair and commission
We complete the repair and run combustion tests, so the burner is left running correctly rather than merely running.
What happens on an oil repair visit
Oil systems have more moving parts than gas ones, so a proper diagnosis covers the fuel path as well as the appliance.
- A full check of the burner, including the nozzle, electrodes and photocell
- The fuel supply line, filter and de-aerator checked for air, blockage and water ingress
- The tank inspected for water, sludge and contamination where the fault suggests it
- Combustion testing to confirm the burner is running correctly once repaired
- Common failure parts carried on the van, including nozzles, filters and photocells
- A clear explanation of what failed, why it failed and how to reduce the chance of a repeat
- An honest view on repair against replacement where the boiler is near the end of its life
If we find the fuel itself is the problem we will say so, rather than fitting parts that will fail again in a month.
Why oil boilers lock out
A lockout is a safety response, not a fault in itself. The burner has tried to light, failed to detect a flame within a set period, and shut down rather than continue pumping oil into a chamber that is not burning it. Pressing reset asks it to try again, and if nothing has changed it will simply lock out once more.
The usual culprits are a worn or partly blocked nozzle, a dirty photocell that cannot see the flame, air in the supply line after the tank has run low, or water that has found its way into the fuel. None of those is fixed by resetting.
Repeated resetting is worth avoiding, too. Each attempt sprays more unburnt oil into the combustion chamber, which makes the eventual restart messier and can foul the boiler further. Two failed resets is the point to stop and call someone.
Oil boiler repair questions, answered
My oil boiler has locked out and will not reset. What now?+
A lockout means the burner tried to light and failed, so resetting without fixing the cause will only repeat it. Stop after two attempts and call us, because further resets push unburnt oil into the combustion chamber.
Why will my oil boiler not fire up?+
The usual causes are a worn nozzle, a dirty photocell, air in the supply line after the tank has run low, or water in the fuel. It is far more often the fuel path than the boiler itself.
Can water get into my oil tank?+
Yes, through condensation or a failed seal, and it is a common cause of repeat breakdowns. If the fuel is contaminated, fitting new boiler parts only buys a few weeks.
Do you carry oil boiler parts on the van?+
Yes. We stock nozzles, filters, photocells and the other components that fail most often, so many oil repairs are completed on the first visit.
I ran the tank low and now it will not start. Is that related?+
Almost certainly. Running a tank very low draws sludge from the bottom and lets air into the supply line, and the system usually needs bleeding and the filter checking.
Are you OFTEC registered?+
Yes. All oil work is carried out under OFTEC registration, and we are Gas Safe registered for gas work as well.
Should I repair or replace an ageing oil boiler?+
If the same component keeps failing or parts are getting hard to source, replacement usually wins over a few years. We will give you a straight answer rather than pushing an installation.
What local customers say
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Free, no-obligation quote. Gas Safe and OFTEC registered.
Page last updated: 27 August 2026