Boiler Plus: what must installers fit?

Ask a room of installers what Boiler Plus means and the efficiency figure comes back straight away, then a pause when someone asks which of the four extras actually count. This guide covers what it requires at the point of install in England, the four qualifying measures for a combi, where smart controls and OpenTherm sit, and how it lands in your paperwork.

What is Boiler Plus?

Boiler Plus is the shorthand for a package of standards for domestic boiler installations in England that came into force on 6 April 2018, through changes to Approved Document L of the Building Regulations and the associated Domestic Building Services Compliance Guide. It is not a separate law, and there is no such thing as a Boiler Plus certificate. It is the bar being raised inside the Building Regulations, aimed at what happens after the boiler is on the wall rather than at the boiler alone. An efficient appliance controlled badly is an inefficient heating system, and the standard closes that gap. Building standards are devolved, so it is England only: Scotland, Wales and Northern Ireland set their own requirements and their own notification arrangements, which is worth confirming if your patch straddles a border.

What must every boiler installation include?

• A minimum seasonal space heating efficiency of 92% ErP for the boiler being installed.
• Time control and temperature control, present and working, so the system is not simply running to a boiler thermostat.
• A boiler interlock, so the appliance is not firing when there is no demand for heat.
• On a combi, one of the four additional measures set out below.

These bite on boiler replacements in existing dwellings in England, and the controls requirement reaches oil as well as gas. On most jobs that is a programmer and a room thermostat you would have fitted anyway. The part that changes the quote is the combi measure.

What are the four options for a combi?

A combi installation must include at least one of four measures, and one is enough. The factsheet lists them as flue gas heat recovery, weather compensation, load compensation, and smart controls with automation and optimisation:

• Flue gas heat recovery: recovers heat from the flue products to preheat domestic hot water, so less gas is burned to reach the same tap temperature.
• Weather compensation: an outside sensor lets the boiler drop its flow temperature when the weather is mild, instead of running hot and cycling.
• Load compensation: the control works from the gap between room temperature and setpoint, and asks the boiler for the flow temperature the property needs.
• Smart controls with automation and optimisation: a control that learns how quickly the property gains and loses heat and adjusts timing and settings accordingly, rather than switching on at a fixed hour.

Which option should you fit?

That depends on the job, and it is your decision with the customer rather than the regulation's. Flue gas heat recovery is a survey decision, because it needs the space and a flue arrangement that suits, and it disappears into the install with nothing for the customer to switch off. Weather and load compensation both depend on the boiler accepting the control signal, which means reading the installation instructions before you promise anything on a quote. Smart controls are the option customers ask for by name, and the one most likely to generate a callback if the handover gets rushed. Whichever route you take, the compliance question is the same: is one qualifying measure fitted, commissioned and recorded.

Where do smart controls and OpenTherm fit?

This is where installs go wrong, so it is worth being precise. Smart controls qualify where they deliver automation and optimisation, not simply because an app exists. A thermostat you can turn up from the bus is a convenience feature; what the standard looks for is a control that automates settings and optimises how the property is heated. Plenty of controls sold as smart do both; some do not. The specification sheet, not the box, settles it.

OpenTherm sits alongside this rather than inside it. It is an open communications protocol that lets a control and a boiler exchange more than an on or off signal, which is what makes modulating and compensating control possible on an appliance that supports it, and where both ends support it, it is one common way of delivering load compensation. What this guide will not give you is a compatibility table. Which boilers and controls work together, and in which mode, varies by model and firmware, and any such list published on a website is out of date within months. Rely on the boiler's installation instructions and the control manufacturer's own compatibility information, for the models on the job you are quoting.

How does Boiler Plus interact with Building Regulations compliance?

Directly, because Boiler Plus is Building Regulations. Installing a boiler is notifiable building work, and the normal route for a Gas Safe registered business is self-certification through the competent person scheme: you notify the installation to Gas Safe Register, and the householder gets a Building Regulations compliance certificate off the back of it. Notifying an install that does not meet the standards does not make it compliant; it records a non-compliant installation against your registration.

Alongside the notification sits the commissioning record. The Benchmark checklist is where the controls fitted with the system get written down, and where you confirm the customer was shown how to use them, which for a compensating or smart control is no formality: a setup the customer disables in week two saves nothing. Three documents, three jobs. The Benchmark checklist is the commissioning record, the compliance certificate follows the notification, and the CP12 is the annual landlord gas safety record, which has nothing to do with installation day.

How do you keep the evidence together?

Boiler Plus is not hard to comply with. It is easy to be unable to prove you complied with, two years on, when a customer disputes what was fitted. The measure you chose, the commissioning record, the notification reference and a photo of the installed control are all evidence. Manifold keeps the job, the certificates and the photos against the property, so the install and the services that follow sit in one history rather than five places.