# The Boiler (Efficiency) Regulations 1993, Paragraph 7


A back boiler or boiler designed to be installed in the living space where—
(a) the efficiency of such a boiler at effective rated output and at 30 per cent part load is equal to or greater than the efficiency requirements for standard boilers minus 4 per cent;
(b) in the case of a boiler designed to be installed in the living space, it bears on its casing the explicit indication that it must be installed in a living space.

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Source: https://www.legislation.gov.uk/uksi/1993/3083/schedule/3/paragraph/7 (the official version)
Page: https://openlegislation.uk/boiler-efficiency-regulations-1993/schedule-3/paragraph-7
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.