The Boiler Plus regulations require every new gas or oil boiler fitted into an existing home in England to come with time and temperature controls and a boiler interlock. A gas combination boiler must also come with at least one of four extra measures: flue gas heat recovery, weather compensation, load compensation, or a smart thermostat with automation and optimisation. The standards took effect in April 2018 through Approved Document L, the statutory guidance to Part L of the Building Regulations 2010, and they apply in England. This page sets out what must be fitted, who may fit it and what paperwork you should end up holding.
What are the Boiler Plus regulations and where do they apply?
Boiler Plus is the name given to the boiler and controls standards that came into force in England in April 2018. The standards sit in Approved Document L, the statutory guidance to Part L of the Building Regulations 2010. They apply to work in England. Scotland and Wales set their own building standards.
Boiler Plus is not a separate Act of Parliament. It changed what Approved Document L expects when a gas or oil boiler is fitted into an existing home. Three things are covered: the efficiency of the appliance, the heating controls fitted with it, and one extra energy-saving measure for gas combination boilers.
Which controls must every new gas or oil boiler in England come with?
Every new gas or oil boiler fitted into an existing home in England must come with time and temperature controls and a boiler interlock. Time control is the programmer or timer that sets when the heating runs. Temperature control is the room thermostat or an equivalent device. A boiler interlock is the control arrangement that stops the boiler firing when nothing in the house is calling for heat.
A gas boiler going into an existing dwelling must also meet a minimum efficiency of 92% ErP. ErP is the seasonal efficiency rating shown on the appliance energy label. Approved Document L allows a lower SEDBUK 2009 figure only in exceptional cases, at 78% for natural gas and 80% for LPG.
These controls are part of the boiler installation under Boiler Plus, not an accessory bought later. A quote that lists only the appliance and the labour is worth questioning before you accept it.
Which extra measure must a gas combi boiler come with under Boiler Plus?
A gas combination boiler fitted into an existing home in England must come with at least one of four extra measures, chosen to suit the system. Approved Document L Volume 1 sets out the four options.
- Flue gas heat recovery, which takes heat out of the flue gases and uses it to pre-heat the hot water
- Weather compensation, which varies the boiler flow temperature according to the outdoor temperature
- Load compensation, which varies the flow temperature according to the heat the house is calling for
- A smart thermostat with both automation and optimisation
Government guidance is specific about the fourth option. A smart control meets the requirement either because it provides load or weather compensation, or because it has both automation and optimisation. Automation means the device adjusts heat output itself, from a programmed demand or from detecting whether anyone is home. Optimisation means it calculates when to start so the target temperature is reached at the time you want it, using as little energy as possible.
The extra measure applies to gas combis. If you are still deciding between boiler types, our guide on combi, system or regular boilers explains how each one works.
Weather compensation or load compensation: how the two Boiler Plus measures differ
Weather compensation and load compensation are two of the four extra measures a gas combi boiler can be fitted with under Boiler Plus in England. Both vary the boiler flow temperature, but they take their reading from different places.
| Point of difference | Weather compensation | Load compensation |
|---|---|---|
| What the control reads | Outdoor air temperature, from a sensor fitted on an outside wall | The rise in return water temperature after the boiler fires |
| How the flow temperature is set | Flow temperature follows the outside weather and drops as conditions get milder | The boiler works out the load being called for and trims the flow temperature to match |
| What gets fitted | An external sensor plus a boiler and control that accept that sensor | A modulating room control, often an OpenTherm thermostat, paired with a compatible boiler |
| Compatibility to check | The boiler needs an input for a weather sensor from the matching control range | Boiler and thermostat must both support OpenTherm, usually shown by the logo on the box |
Which of the two suits your home depends on the boiler, the controls already wired in and how the radiators are run. OpenTherm needs compatibility on both sides, and older boilers often do not have it. The choice is made on site, which is one of the things a free boiler survey settles before any price is written down.
Can you ask your installer to leave the Boiler Plus measure out?
No. The Boiler Plus standards are mandatory for every installer working in England and there is no opt-out. The government clarification for installers and consumers states that an installer must not carry out a non-compliant installation, even where the customer asks for one. Asking to save on the controls puts the installer in breach, not you in credit.
Under Boiler Plus in England the controls are part of the boiler installation, not an optional extra. A quote for a gas combi that leaves out time and temperature control, a boiler interlock, or one of the four extra measures is not a compliant job.
Who may fit a boiler to Boiler Plus standards, and what paperwork follows?
Gas work on a boiler must be carried out by a Gas Safe registered engineer. The Gas Safety (Installation and Use) Regulations 1998, as amended, require a business doing gas work to be on the Gas Safe Register. HSE states that work on gas fittings in a home may only be done by a registered engineer who is qualified for that work, and that includes moving, servicing and altering an appliance, not just fitting one.
An installer registered with a competent person scheme can self-certify that the work meets the Building Regulations. That removes the need for you to apply to building control yourself. Under the gov.uk guidance the scheme notifies the local authority, and the householder receives a certificate within 8 weeks of the work being completed. Keep it with the appliance paperwork, as a buyer's solicitor will ask for it; our guide to the building regulations compliance certificate explains what the document shows.
Does Boiler Plus change when the new Approved Document L starts in 2027?
The combi boiler rule carries over. A 2026 edition of Approved Document L Volume 1 has been published, and it still lists flue gas heat recovery, weather compensation, load compensation and a smart thermostat with automation and optimisation as the four options for a gas combi.
The revised Approved Documents apply from 24 March 2027, and from 24 September 2027 for higher-risk building work, subject to transitional arrangements. Until then the 2021 edition incorporating the 2023 amendments is the version that applies to boiler work in England. A separate government consultation on boiler standards and efficiency has been running in the background, so it is worth checking the current edition at the time your boiler is fitted.
If you are replacing a boiler in London or the surrounding counties, our new boiler installation service starts with a free home survey. The controls your installation needs are set out in the written fixed price before any work begins.
Sources
- Boiler Plus: new standards for domestic boiler installations from April 2018 (factsheet)
- Clarification on the Boiler Plus regulations for installers and consumers
- Approved Document L, Conservation of fuel and power, Volume 1: Dwellings (2021 edition incorporating 2023 amendments)
- Approved Document L, Volume 1: Dwellings (2026 edition)
- Amendments to Approved Documents L and F, Circular 04/2026
- Building regulations approval: use a competent person scheme
- HSE — Domestic gas: frequently asked questions
- Viessmann — Understanding OpenTherm systems