Boiler Plus in 2026: The Four Options, and Which One Suits a Cornish Home

What Boiler Plus requires

Since April 2018, a gas boiler installed in a home in England has had to meet a minimum standard known as Boiler Plus. Three parts of it apply to every installation:

• the boiler must be at least 92% ErP efficient;
• the system must have time and temperature control; and
• on a combi, the installation must include one additional measure from a list of four.

The four are flue gas heat recovery, weather compensation, load compensation, and smart controls with automation and optimisation. They are presented as equivalent. In a real house they are not, and which one you get is usually decided by the installer's habit rather than by your building.

Option 1: flue gas heat recovery

A heat exchanger in the flue takes residual heat from the exhaust gases and uses it to pre-warm incoming mains water. It is hardware: once fitted it works without anyone setting anything, which is its great advantage. It helps most in a household that draws a lot of hot water — a family with two showers running morning and evening — and least in a household that uses little.

Option 2: weather compensation

An external sensor measures outside temperature and the boiler lowers its flow temperature when the weather is milder, instead of firing at full temperature and relying on the thermostat to stop it. A condensing boiler is at its most efficient when the return water is cool enough to keep it condensing, so running cooler for most of the year is exactly the right behaviour.

This is the option that suits the Cornish climate best. The county's winters are mild and long rather than sharp and short: there are a great many days here that are too cool to leave the heating off and far too mild to need 75 °C flow. Weather compensation spends the whole of that season running the boiler in its efficient band.

Option 3: load compensation

Same principle, different input: instead of outside temperature, the control uses the difference between the room temperature and the target, and modulates the flow temperature accordingly. It responds to how the house is actually behaving — including solar gain through a south-facing window on a bright February afternoon, which weather compensation alone will miss.

Option 4: smart controls

A smart thermostat qualifies only where it includes automation and optimisation — not merely an app that lets you turn the heating on from the pub. Optimisation means the control learns how long the house takes to warm and starts accordingly, rather than firing at a fixed time.

It is the most popular option because it is the most visible one, and it is a perfectly good choice in a house where the occupancy pattern varies. In a house where someone is home all day on a steady schedule, it will do less than weather compensation would.

Which one suits a Cornish home

Our general view, which an installer should be willing to argue with you about rather than simply assert:

• Solid-wall stone or granite property, heating on most of the winter: weather compensation. The long mild season is where it earns its keep.
• Busy family house, high hot-water draw: flue gas heat recovery, because the saving follows the hot water rather than the heating.
• Irregular occupancy — holiday let, shift work, a house empty midweek: smart controls with optimisation.
• Big south-facing glazing: load compensation, which sees the solar gain the weather sensor cannot.

What this means when you compare quotes

Two quotes for the "same" boiler can differ by a few hundred pounds entirely because of this clause — one includes a learning thermostat and the other a flue heat recovery unit. When you compare, ask each installer which of the four their price includes and why they picked it for your house. An installer who cannot name the measure is either not including one, or has not read the rule.

One more thing worth knowing if you are off the gas grid, as roughly 47% of Cornish homes are: none of this applies to an oil boiler, and the decision you are actually making may not be a boiler decision at all. See boiler installation Cornwall for what each job type costs, and the Boiler Upgrade Scheme in Cornwall for the £9,000 that is available to off-gas oil and LPG homes replacing with a heat pump, against £7,500 elsewhere.