# The Boiler (Efficiency) Regulations 1993, Schedule 2: THE EFFICIENCY REQUIREMENTS


Boilers must comply with the useful efficiency requirements set out in the Table below —
(a) at rated output, that is, operating at rated output Pn expressed in kW, at an average boiler-water temperature of 70°C, and
(b) at part load, that is, operating at 30% part load, at an average boiler-water temperature which varies according to the type of the boiler.
Table
Type of boiler
Range of power output
Efficiency at rated output
Efficiency at part load
kW
Average boiler-water temperature expressed in °C
Efficiency requirement expressed in %
Average boiler-water temperature expressed in °C
Efficiency requirement expressed in %
* Including condensing boilers using liquid fuels.
** Temperature of boiler water supply.
Standard boilers
4 to 400
70
≥84 + 2 log Pn
≥50
≥80 + 3 log Pn
Low temperature boilers
4 to 400
70
≥87.5 + 1.5 log Pn
40
≥87.5 + 1.5 log Pn
Gas condensing boilers
4 to 400
70
≥91 + 1 log Pn
30
≥97.1 + 1 log Pn

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Source: https://www.legislation.gov.uk/uksi/1993/3083/schedule/2 (the official version)
Page: https://openlegislation.uk/boiler-efficiency-regulations-1993/schedule-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.