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What is boiler plus?

Boiler Plus is an addition to Part L of the Building Regulations introduced by the Department for Business, Energy and Industrial Strategy (BEIS). It sets out new requirements for heating engineers fitting new boilers and heating controls, with the aim of reducing domestic carbon emissions and encouraging energy efficiency. Boiler Plus applies to the minimum requirements of installing boilers in existing buildings in England only as of 6th April 2018.

What is the purpose of the law?

The new law is designed to help meet the UK's commitment to lowering green house gas emissions by reducing domestic carbon emissions and increasing energy efficiency in UK homes.

What does the law state?

The new law has three main components:

  1. Any gas boilers installed or replaced must be minimum 92% efficient under the ErP European Rating System.
  2. Boiler interlock, time and temperature controls must be present and operational for all boilers if they are new, replacements or upgrades. This also applies to oil boilers.
  3. ​When replacing a gas fired combi boiler one of four energy saving measures must be selected and installed alongside time and temeperature controls. The available options​ are; smart thermostat (capable of optimisation and automisation), outdoor weather sensor installed on a north facing wall, load compensation or flue gas heat recovery (FGHR)


Which device should I choose?

What is a smart thermostat? A smart thermostat is any thermostat which has 1) Automation – a control function which automatically adjusts time and temperature settings based on occupancy detection and/or stored data from user adjustments over time and 2) Optimisation – a control function which starts the boiler operation at the optimum time to achieve the set-point temperature at the start of the occupancy period

What is weather compensation? Weather compensation devices enable the boiler to read the outside temperature via a sensor so that the boiler can adjust the temperature of your heating accordingly.
What is load compensation? Load compensation measures the response of the heating system and adjusts the flow temperature based on what is needed to reduce fuel consumption.

What is FGHR? A Flue Gas Heat Recovery (FGHR) is a device designed to improve energy efficiency of the boiler by recycling the heat from the flue gases which would usually be lost into the atmosphere. Instead this heat is used it to preheat domestic hot water.

For a more in depth look at these devices click here.

For the majority of consumers, installing a smart thermostat makes the most economic sense as this allows you to meet the requirement for dual time and temperature controls and the additional energy saving measure using one single device. It is possible to get thermostats with load compensation built in and this could also prove a cost effective way for consumers to comply with the new legislation. A weather compensator needs to be installed on a north facing wall and this will inevitably increase the cost of an installation due to the added labour involved, on top of the cost of the device, however, weather compensators' can be cost effective if a compliant stat is already fitted. Flue gas heat recovery is an expensive device; prohibitively so for most consumers. As such FGHR is not recommended for most combi installations as the return on investment is so long.

Further reading

More information about boiler plus is available from the Department for Business, Energy & Industrial Strategy

For Boiler Plus consultation response click here

For Boiler Plus impact assessment click here

For Boiler Plus FAQ click here

For Heat in Buildings consultation document click here

For Heat in Buildings impact assessment click here