Boiler Plus Legislation: Minimum Heating Control Requirements from 2018

Summary

Boiler Plus was introduced to reduce the energy consumption of domestic heating by requiring modern controls to accompany every new boiler installation. Prior to 2018, it was legal to install a new boiler with only basic on/off controls — this meant many new boilers operated inefficiently, cycling between full output and off rather than modulating to meet demand. The legislation mandates more sophisticated control to extract real-world efficiency from modern condensing boilers.

The practical implication for installers is that every new gas boiler installation in England must now include the Boiler Plus controls package or the customer must have an existing system that meets the minimum requirements. This affects quoting — the cost of compliant controls must be included in the price. It also affects existing system assessments: a like-for-like boiler replacement requires controls upgrade unless the existing system already meets the standard.

Understanding the four permitted efficiency measures is important because the right choice depends on the system type, property, and customer budget. Weather compensation and load compensation are the most technically sophisticated options; smart thermostats with automation are the most commercially promoted but require a reliable internet connection and customer engagement to deliver claimed savings.

Key Facts

• Boiler Plus — statutory guidance under the Domestic Building Services Compliance Guide (2018 onwards)
• Applies to — all new gas boiler installations in England (like-for-like replacements included)
• Not applicable to — existing boilers without service/replacement; oil, LPG, heat pumps (separate standards)
• Minimum baseline controls (all installs):
  • Room thermostat (or programmable room thermostat)
  • Time programmer (or combined with room thermostat)
  • TRVs on all radiators except the one in the room where the thermostat is located
• One of four additional measures required:
  1. Time and temperature zone control (separate programmer for upstairs/downstairs)
  2. Load compensation (boiler modulates based on room temperature feedback)
  3. Weather compensation (boiler modulates based on external temperature sensor)
  4. Smart thermostat with automation and optimum start (e.g., Nest, Hive, Tado compliant products)
• SEDBUK — Seasonal Efficiency of Domestic Boilers in the UK; minimum efficiency for new boilers is typically 92% (ErP Class A)
• TRV exempt radiator — the radiator in the room containing the room thermostat must not have a TRV (creates conflict between zone and room control)
• Scotland — separate regulations under Scottish Building Standards Section 6 (Energy); similar but not identical requirements
• Wales and Northern Ireland — covered under respective building regulations; broadly similar to Boiler Plus intent
• Landlord obligations — all rental properties must have adequate heating controls; EPC requirements drive further upgrades

Quick Reference Table

Detailed Guidance

The Four Efficiency Measures: Choosing the Right One

Option 1: Time and Temperature Zone Control This requires the heating system to have at least two independently programmable zones — typically upstairs and downstairs, or living areas and bedrooms. This requires a two-zone system (S-plan or similar) with separate zone valves and programmers. The added cost (zone valve, programmer, wiring) is offset by energy savings from not heating unoccupied zones. This is often the most appropriate retrofit for a 3-4 bedroom family home.

Option 2: Load Compensation Load compensation means the boiler adjusts its flow temperature based on the difference between the room temperature setpoint and the actual room temperature. If the room is close to setpoint, the boiler reduces its output (lower flow temperature, better condensing). If the room is cold, the boiler increases output. Load compensation requires the room thermostat to communicate with the boiler via OpenTherm or proprietary protocol. Many modern boilers have this built in — it simply requires the correct control to be fitted. This is often the most cost-effective option in simpler systems.

Option 3: Weather Compensation Weather compensation uses an external temperature sensor to determine the boiler flow temperature — colder outside, higher boiler output. This is the technically superior option for matching boiler output to true heat demand. Weather compensation works best with low-mass emitters (panel radiators, UFH) and reduces condensing boiler cycling to a minimum. An external sensor must be installed in a shaded, north-facing location — not in direct sun. Weather compensation requires OpenTherm or equivalent communication between sensor and boiler.

Option 4: Smart Thermostat with Automation Smart thermostats (Nest, Hive, Tado, Honeywell Evohome, etc.) qualify if they include: remote control via smartphone, learning or adaptive features (such as geofencing-based auto setback), and optimum start (turning on heating early to achieve setpoint by the desired time). Not all smart thermostats qualify — check the product against the Boiler Plus guidance. Simple remote-controllable thermostats without automation do not meet the standard.

TRV Requirements

TRVs (Thermostatic Radiator Valves) must be fitted to all radiators except:

• The radiator in the room where the room thermostat is installed
• Bathrooms (where a TRV is acceptable but not required)

The reason for excluding the thermostat radiator: if the TRV turns off the radiator in the thermostat room, the thermostat may never reach its setpoint and the boiler will run continuously. The radiator in the thermostat room acts as the reference emitter.

TRV minimum specification for Boiler Plus: TRV3 or equivalent (2–7°C temperature range, interchangeable heads). Many installers default to Honeywell T4000 or Danfoss RA-N series. Note that premium TRVs (Danfoss Living, Nest-compatible heads) cost more but offer better temperature accuracy and compatibility with smart systems.

Combi Boilers and Zone Controls

Combi boilers present a specific challenge for zone control: there is no separate cylinder, so hot water zone control is not applicable. For combis, the Boiler Plus efficiency measure applies only to space heating. The most practical options for combi systems are:

• Smart thermostat with automation (Nest, Hive, Tado — all have combi-compatible wiring)
• Weather compensation (external sensor + OpenTherm connection)
• Load compensation (if supported by the specific boiler model)

For combi boilers with a simple two-wire (on/off) connection only, weather and load compensation may require a gateway device or may not be fully supported — check the boiler manufacturer's compatibility guide.

System Commissioning and Documentation

Boiler Plus compliance must be evidenced. When completing a Benchmark Commissioning Document (which must be completed for every new boiler installation), the controls installed must be recorded. Gas Safe engineers should keep a copy and leave one with the householder.

Building Control sign-off for new boiler installations (via the Gas Safe competent person scheme) requires confirmation that controls meet the minimum standard. A like-for-like replacement boiler fitted with sub-standard controls can result in a failed Building Control sign-off.

Frequently Asked Questions

Does Boiler Plus apply if I'm just replacing an old boiler like-for-like?

Yes. A like-for-like boiler replacement in England is treated as a new installation for the purposes of Boiler Plus. You must assess the existing controls and upgrade to the minimum standard if they are non-compliant. This is commonly needed when replacing boilers in older properties that have only basic programmer and no TRVs.

My customer doesn't want to upgrade the controls — what do I do?

You should explain that controls upgrades are a legal requirement under Boiler Plus and cannot be omitted from the installation. Document the conversation. If the customer refuses to allow compliant controls, you cannot lawfully complete the installation and notify it as compliant. In practice, most customers accept the controls requirement when the energy-saving benefit is explained — the payback period on a good smart thermostat is typically 2–4 years.

Does weather compensation work in all systems?

Weather compensation is most effective in hydronic heating systems (radiators or UFH) where flow temperature can be varied without affecting system reliability. It is less effective in systems where there is a large thermal mass (older cast-iron radiators, thick screed UFH) because the slow response time reduces the system's ability to track the weather-compensated setpoint. For best results, combine weather compensation with room thermostats that allow fine-tuning (weather comp sets the baseline, room thermostat trims for occupancy).

Is a Nest or Hive thermostat automatically Boiler Plus compliant?

Not automatically. The specific product must include automation features (geofencing, learning, or optimum start). Nest Learning Thermostat (2nd and 3rd gen) and the Nest Thermostat E (with learning enabled) qualify. Hive Active Heating with geofencing enabled qualifies. Tado Smart Thermostat qualifies. Basic Hive or Nest products without the automation features do not. Always check the current HHIC or BEAMA guidance on qualifying products.

What controls are needed for a system boiler with an unvented cylinder?

For a system boiler (not combi), the minimum controls are: room thermostat, programmer, cylinder thermostat, TRVs on all radiators except the thermostat room, and motorised valve(s) for zone control. The Boiler Plus additional measure (one of four) applies to the space heating circuit. The cylinder thermostat must be set to at least 60°C to prevent Legionella risk. A cylinder limit thermostat (high limit cut-out) is also required.

Regulations & Standards

• Domestic Building Services Compliance Guide (2018) — Boiler Plus requirements for England; issued under Approved Document L

• Approved Document L1A/L1B — Energy efficiency for new dwellings and existing dwellings

• Energy Efficiency (Private Rented Sector) Regulations — Minimum EPC rating for rented properties (currently EPC E)

• Building Regulations Part L (Scotland) — Scottish equivalent requirements (Section 6 of Scottish Building Standards)

• BS EN 215 — Thermostatic radiator valves; requirements and test methods

• HHIC — Boiler Plus Guidance — Industry summary of Boiler Plus requirements

• BEAMA — Controls Compliance Guide — Qualifying products and smart thermostat guidance

• BEIS — Boiler Plus Policy Summary — Original government consultation and final guidance

• Gas Safe Register — Installation Standards — Benchmark commissioning documentation requirements

• heating controls — Full heating controls comparison including smart thermostats

• boiler selection — Boiler sizing and specification

• flue types — Flue installation requirements

• competent person — Gas Safe and other competent person schemes