Oil Boiler FAQs
Frequently asked questions about oil heating systems.
What is OFTEC certification and why does it matter?
OFTEC (Oil Firing Technical Association) is the registration scheme for oil heating engineers, equivalent to Gas Safe for gas work. An OFTEC registered engineer can self-certify oil heating installations and issue the necessary compliance certificates. It is a legal requirement for all new oil boiler installations and major modifications to be carried out by an OFTEC registered technician.
How often should an oil boiler be serviced?
Oil boilers should be serviced annually by an OFTEC registered engineer. Oil combustion is inherently more sooty than gas, meaning components such as the nozzle, electrode, and heat exchanger require more frequent cleaning and replacement. Skipping a service significantly increases the risk of boiler failure and carbon monoxide exposure.
Are all new oil boilers condensing?
Yes. Since 2007 it has been a legal requirement in England and Wales to fit a condensing oil boiler when replacing an existing oil boiler (with limited exceptions). Condensing oil boilers extract additional heat from the flue gases, achieving efficiencies of 90%+ compared to 70–80% for older non-condensing models. This translates to meaningful reductions in oil consumption.
What are the regulations around domestic oil tanks?
Domestic oil storage tanks must comply with Building Regulations Part J and the Oil Storage Regulations. Key requirements include: minimum 10-litre capacity bund (secondary containment) for tanks over 3,500 litres, or bunded tanks for tanks over 2,500 litres near watercourses; adequate distance from buildings and boundaries; oil supply pipework must be protected and terminated correctly. We can advise on tank compliance during your survey.
How efficient are modern oil boilers?
Modern condensing oil boilers achieve efficiency ratings of 90–94%, earning an A or A+ ErP rating. This compares very favourably with the non-condensing boilers installed before 2007, which were often 65–75% efficient. Upgrading from an old oil boiler can reduce your heating oil consumption by 20–30%.
How does oil heating compare to gas?
Mains gas is generally cheaper per kWh than heating oil in the UK, though oil prices can fluctuate significantly. Gas boilers tend to require less frequent servicing than oil boilers. For properties that are off the mains gas grid, oil remains a very popular choice due to its relatively high energy density and the wide availability of OFTEC-qualified engineers.
What is the difference between kerosene and gas oil?
Kerosene (28-second oil, also called Class C2) is the standard domestic heating oil used in most UK homes. It burns more cleanly and is more suitable for modern condensing boilers. Gas oil (35-second oil, also called red diesel) is a heavier fuel typically used in older non-condensing boilers and some commercial applications. Always use the fuel specified by your boiler manufacturer.
Can I convert my oil boiler to a heat pump?
Yes, and off-gas properties such as oil-heated homes are exactly the type of property the government's Boiler Upgrade Scheme was designed to support. The £7,500 BUS grant makes heat pump conversion financially attractive for oil heating households. Our engineers can carry out a full suitability assessment and provide a clear comparison of projected running costs.
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