Boiler Plus is the standard, introduced through Building Regulations Part L in April 2018, that sets a minimum efficiency requirement for new and replacement boilers in England, plus an additional energy-saving measure specifically required for combi boiler installations.

What Boiler Plus actually is

Boiler Plus is the informal name for a set of standards brought in under the 2018 update to Part L of the Building Regulations in England, aimed at improving the real-world energy efficiency of domestic heating systems, reducing carbon emissions, and helping households cut running costs. It applies specifically to new boiler installations and boiler replacements, rather than being a retrospective requirement on boilers already installed before the rules changed — if you’re not currently replacing a boiler, Boiler Plus doesn’t create any new obligation on the system you already have.

The baseline requirements for every boiler

Under Boiler Plus, every new or replacement boiler — combi, system or regular — must meet a minimum efficiency standard of at least 92% ErP (Energy-related Products) efficiency, and must be installed with a boiler interlock incorporating both time and temperature controls. In practice, this baseline requirement rules out installing a genuinely low-efficiency replacement boiler, and ensures every new installation has proper functional controls governing when the system runs and at what temperature, rather than a simple on/off arrangement with no real temperature management.

The extra requirement specifically for combi boilers

Combi boiler replacements have one further requirement on top of the baseline standard: the installation must also include one of four specific additional energy-saving measures. These are weather compensation, which adjusts the boiler’s output based on outdoor temperature; load compensation, which adjusts output based on how close the home is to the desired temperature; smart heating controls, which allow more sophisticated scheduling and remote control of the heating system; or flue gas heat recovery, which captures and reuses some of the heat that would otherwise be lost through the flue. An installer has to choose and fit one of these four options as part of a compliant combi installation — it isn’t a menu of nice-to-haves, it’s a mandatory part of meeting the standard for this specific boiler type.

Is any of this optional?

• No — Boiler Plus requirements are a legal part of the Building Regulations for qualifying installations in England, not a voluntary best-practice recommendation an installer can choose to skip.
• There’s no general opt-out available simply because a customer would prefer a cheaper, more basic installation without the additional control or feature.
• An installation that doesn’t meet the standard isn’t properly compliant, which can create problems with Building Regulations sign-off and any related paperwork, regardless of whether the boiler itself otherwise works.

What this means when comparing quotes

Because Boiler Plus compliance is mandatory for a qualifying combi replacement, a genuinely comparable quote should already include the cost of meeting it — the minimum efficiency boiler itself, plus whichever of the four additional measures the installer proposes. If one quote looks noticeably cheaper than others for what’s supposedly the same job, it’s worth specifically asking which Boiler Plus measure is included and confirming the boiler’s stated ErP efficiency rating, since a non-compliant quote isn’t actually a legitimate lower-cost version of the same installation — it’s a different, non-compliant job that happens to look similar on paper.

Why the standard was introduced in the first place

Boiler Plus followed government analysis suggesting that boilers were often not performing anywhere near their laboratory-rated efficiency once installed in real homes, largely because of how they were being controlled day to day rather than any fundamental flaw in the appliances themselves. A highly efficient boiler running with poor or absent controls can still waste a meaningful amount of energy through unnecessary cycling, overheating rooms that don’t need it, or simply running longer than actually required to reach a comfortable temperature. Requiring genuine interlock controls as standard, and an additional smart or compensating measure specifically for combi boilers, was intended to close that gap between how efficient a boiler could theoretically be and how efficiently it actually runs once fitted in an ordinary household.

FAQs

Does Boiler Plus apply if I’m just having my existing boiler serviced, not replaced?

No — Boiler Plus requirements are triggered by a new or replacement boiler installation, not by routine servicing or repair of an existing appliance that isn’t being replaced.

Can I choose which of the four combi measures gets installed?

Often yes, within what your installer offers and what suits your property — weather compensation, load compensation, smart controls and flue gas heat recovery each work slightly differently, so it’s worth discussing with your installer which genuinely fits your home and habits best, rather than simply accepting whichever is cheapest for them to fit.

Does a system or regular boiler need one of the four extra measures too?

No — the extra requirement for one of the four additional energy-saving measures specifically applies to combi boiler replacements. System and regular boilers still need to meet the baseline 92% efficiency and time-and-temperature control requirements, but not this additional combi-specific measure.

Sources

This guide draws on the following primary sources, current as of 16 September 2026:

• gov.uk: Boiler Plus — new standards for domestic boiler installations factsheet

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