Advise and tips
Why Your Oil Boiler Needs an Annual Service: Advice for Off-Grid Homes in Somerset, Devon and Dorset
5 August 2026
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Why Your Oil Boiler Needs an Annual Service: Advice for Off-Grid Homes in Somerset, Devon and Dorset
Drive ten minutes out of most towns in our area and you are quickly into countryside where the mains gas network simply does not reach. For a great many homes across rural Somerset, Devon and Dorset, heating and hot water come from an oil-fired boiler and a tank in the garden. Around 1.5 million homes in the UK heat this way, and when an oil boiler is looked after it is a dependable, powerful bit of kit. Neglected, it can turn messy, inefficient and unreliable, usually at the worst possible moment in the middle of winter.
The single most important thing you can do for an oil boiler is have it serviced once a year by an OFTEC-registered engineer. Here is why that matters, and what a proper service involves.
Oil is different to gas
It is easy to assume all boilers are much the same, but oil-fired systems ask for a bit more care than their gas cousins. Oil burns less cleanly, so soot gradually builds up inside the boiler. The nozzle that sprays the fuel wears over time, filters clog, and the flexible fuel hoses and lines slowly degrade. None of this fixes itself. Left alone, it quietly eats into your boiler's efficiency until the day it locks out and refuses to fire.
That efficiency drop is not just an abstract worry. Industry figures suggest that even a 5% loss of efficiency in an oil boiler can mean burning something like an extra 150 litres of kerosene over a year, which is money going straight up the flue. A clean, well-tuned boiler simply gets more heat out of every litre you pay for.
What OFTEC registration means
OFTEC stands for the Oil Firing Technical Association, set up in 1991 to bring proper standards to the oil heating industry. It runs the registration scheme that certifies engineers as competent to install, service and repair oil-fired systems safely. An OFTEC-registered engineer works to the relevant Building Regulations, including Part J and Part L, and can issue a certificate of compliance for notifiable work.
Because oil heating is far more common in rural areas than in towns, OFTEC-registered engineers are less thick on the ground than Gas Safe ones, which is exactly why it is worth using a local firm that carries the registration and understands off-grid homes well. It is always sensible to check an engineer's credentials and to ask for a certificate after any major work.
What actually happens during a service
A proper oil boiler service is a good deal more than a quick look and a wipe down. A thorough visit will usually include a visual inspection for leaks, corrosion and general wear, cleaning or replacing the nozzle, de-sooting the heat exchanger and combustion chamber, and checking or changing the fuel filter. The engineer will inspect the fuel line and flexible hoses, check the flue, and carry out a combustion and efficiency test to make sure the boiler is burning cleanly and safely. The controls and thermostat get checked too, and a good engineer will take a look at the oil tank and its surroundings while they are there.
That last point is worth flagging. Your oil tank is part of the system, and a split, leaking or ageing tank is both an environmental problem and an expensive one. Keeping an eye on tank condition and fuel levels, especially heading into winter, saves a lot of grief.
Warning signs worth acting on
Oil boilers usually give you some notice before they fail. It is worth booking a service sooner rather than later if you spot any of the following: sooty marks or a smell of oil around the boiler, the boiler frequently locking out or needing to be reset, rumbling or unusual noises when it fires, or a noticeable jump in how much oil you are getting through. Any of these suggests the boiler is not running as it should, and catching it early is almost always cheaper and less disruptive than waiting for a full breakdown.
The best time to book
The ideal time to service an oil boiler is during the warmer months, from late spring through to early autumn, before the heating goes back into daily use. Getting it done then means any parts that need replacing can be sorted without you sitting in the cold, and your system heads into winter in good shape. If your boiler has not been looked at in the last twelve months, though, the best time is simply as soon as you can.
Local, OFTEC-registered help
DC Plumbing and Heating is a family run business based in Chard, and we look after oil-fired heating in off-grid homes right across Somerset, Devon and Dorset. We are OFTEC registered for oil work and Gas Safe registered too, so whatever your home runs on, we can keep it safe and running well.
To book an annual service or talk through a problem with your boiler, give us a call on 01460 357021.
Sources: OFTEC (registration and oil heating standards); industry data on oil boiler servicing and efficiency.



