Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 78·5.30
Shielding of oil-fired appliances
Oil-fired appliances must be located to prevent accidental contact and surrounded by non-combustible surfaces, either using a 25 mm thick non-combustible shield or a 75 mm air space from combustible materials.
An oil-fired appliance should be located where accidental contact is unlikely and it should be surrounded by a non-combustible surface which provides adequate separation from combustible materials. The appliance should be installed –
(a) with a shield of non-combustible material, having a minimum thickness of 25 mm, between the appliance and the combustible material. See Diagram 4.8; or
(b) with an air space of not less than 75 mm between the appliance and the combustible material. See Diagram 4.8.
Source — /Users/richardhill/Documents/planning-arch-project/data/documents/regional/Technical Booklet L - Combustion Appliances and Fuel Storage Systems.pdf