This is perfectly normal and is simply the fuel venting through the weatherproof vent fitted to the oil tank.

Oil storage tanks should never be installed in a habitable area. If installed internally, they should always be contained within an enclosed chamber. Detailed requirements exist for internal oil storage installations. For more information contact your local Building Control Officer or OFTEC.

Oil tanks with a nominal capacity not exceeding 3,500 litres should not be fitted any closer than 1.8 metres to a non-fire rated (30 minute minimum fire resistance) wall or eaves. Where these clearances cannot be achieved, the measures noted in British Standard BS5410 and OFTEC Technical Instruction Book 3 must be provided – i.e. the provision of a 30 minute (minimum) fire resistant wall which extends at least 300mm above and beyond the ends of the oil tank. It will be necessary to protect exposed eaves forming part of a roof within 1.8 metres of the top of an oil tank to provide a minimum of 30 minutes fire resistance. Cladding can be applied to the eaves in order to prevent fire from spreading to the roof.

For oil tanks with a capacity of 3,500 litres or greater, please contact your local Building Control Officer or OFTEC.

Oil tanks with a nominal capacity of less than 3,500 litres should not be placed within 1.8 metres of a flu outlet. Where these distances cannot be achieved, the protection measures noted in OFTEC Technical Instruction Book 3 and British Standard BS5410 must be provided by means of a 30 minute fire resistant wall which extends a minimum of 300mm above and beyond the ends of the tank. For oil tanks with a nominal capacity of 3,500 litres or greater, please contact your local Building Control Officer or OFTEC.

If the oil tank has a nominal capacity of less than 3,500 litres, it should not be placed any closer than 760mm to a boundary. This assumes that there are no flu outlets or buildings between the tank and the boundary. Where these distances cannot be achieved, the protection measures noted in OFTEC Technical Instruction Book 3 and British Standard BS5410 must be provided by means of a 30 minute fire resistant wall which extends a minimum of 300mm above and beyond the ends of the oil tank. For oil tanks with a nominal capacity of 3,500 litres or greater, please contact your local Building Control Officer or OFTEC.

A single skin oil tank consists of a single container in which the fuel is stored. Unlike bunded oil tanks and bunded fuel tanks, single skin oil tanks incorporate no secondary containment. In the event of a spill, a pollution incident occurs.

Single skin oil tanks are not suitable for the storage of fuel at commercial, industrial or institutional premises, or at domestic installations with an installed capacity of over 2,500 litres – unless installed within a suitably bunded area.

For all other installations, an Oil Tank Risk Assessment must be undertaken by a competent person prior to installation and in accordance with the requirements of OFTEC Technical Instruction Book 3. In anticipation of possible future regulations, serious consideration should be given to fitting a bunded tank, even where a single skin tank may currently suffice.