catalytic unitmeans a unit– (a) which contains a catalytic pad;
gas catalytic heatermeans an appliance suitable for use in any dwelling and designed for the heating of space by means of the catalytic oxidation of petroleum gas, being an appliance— (a) in which the source of the petroleum gas is in liquid form;
petroleum gasmeans a hydrocarbon mixture consisting predominantly of butane, butylene, propane or propylene or of any mixture thereof;
unbonded asbestosmeans asbestos which has not been treated by any adhesive or physical process which has resulted in the asbestos fibres cohering together.