Boiler Plus Explained
If you are replacing a gas boiler in England, there is a set of requirements your installation has to meet, and it is worth understanding before you compare quotes rather than after.
It is called Boiler Plus, it came into force in April 2018, and the reason it matters commercially is that a quote which includes it and a quote which does not are not quoting the same job.
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What it requires
Three things.
- 1
Minimum efficiency.
The boiler must achieve at least 92% ErP seasonal efficiency. Every current model from the major manufacturers meets this, so it rarely limits the choice, but it does rule out old stock.
- 2
Time and temperature controls.
The installation must include a programmer and a room thermostat, with boiler interlock so the boiler shuts down when the thermostat is satisfied rather than continuing to cycle.
- 3
For combi boilers only: one additional efficiency measure,
chosen from four.
- Weather compensation using an external sensor to adjust flow temperature to outside conditions
- Load compensation adjusting flow temperature to how much heat the property currently needs
- A smart thermostat with automation and optimisation and not every smart thermostat qualifies
- Flue gas heat recovery which extracts additional heat from the flue gases
Why the fourth option matters when comparing quotes
That additional measure has a real cost, and it is the single most common reason two boiler quotes differ.
If one quote includes a qualifying smart thermostat and another does not, they are not comparable
Ask each installer which measure is included and whether it is in the price. It is a fair question and the answer is informative about the quote as a whole.
Also worth checking: not every smart thermostat on the market meets the requirement. If a specific model is being supplied, confirm it qualifies rather than assuming.
Which measure to choose
- Weather compensation is technically the strongest performer, because adjusting flow temperature to outside conditions keeps the boiler condensing efficiently. It is less flexible if your heating pattern changes.
- A qualifying smart thermostat is the practical choice for most households, because you get compliance and something people will actually use. Scheduling that is easy to change tends to get used, and scheduling on a small grey box in a hallway tends not to.
- Flue gas heat recovery works well and adds physical bulk around the boiler, which matters in a tight space.
Our smart thermostat page covers the controls question in more detail, including the distinction between simple on/off control and modulating control, which is what actually determines whether a smart thermostat improves your efficiency or just your convenience.
The other rule people meet at the same time
Boiler Plus is not the only requirement that has changed.
Part L of the Building Regulations now requires new and fully replaced wet heating systems to be designed for a maximum flow temperature of 55°C, rather than the 75 to 80°C older systems ran at.
The reasoning is the same: a condensing boiler only condenses, and only reaches its rated efficiency, when the return temperature is low enough.
The consequence is radiator sizing. A radiator delivers less heat at a lower flow temperature, so it needs to be larger to do the same job. Radiators sized decades ago for a hotter system will underperform, and the usual response is to turn the flow temperature back up, at which point the efficiency you paid for disappears.
This is the single biggest reason people replace a boiler and do not get the improvement they expected. See our radiator page.
Notification, which is not optional
Every gas boiler installation must be notified to Building Control, which a Gas Safe registered engineer does through the Gas Safe Register. You should receive a Building Regulations Compliance Certificate afterwards.
Keep it with your house paperwork. A buyer’s solicitor will ask for it, and a missing certificate becomes your problem at sale rather than the installer’s.
Questions worth asking any installer
- Which Boiler Plus efficiency measure is included, and is it in the price?
- If it is a smart thermostat, does that specific model qualify?
- What flow temperature is the system being designed around?
- Are the radiators sized for that temperature, or being reused as they are?
- Who notifies Building Control, and when do I get the certificate?
Frequently asked questions
Does Boiler Plus apply to me?
It applies to gas boiler installations in England. Requirements differ in Scotland, Wales and Northern Ireland.
Does it apply to system and regular boilers?
The efficiency and controls requirements apply generally. The additional measure requirement applies to combi installations.
Does it make a new boiler more expensive?
The additional measure has a cost. It is also the thing most often left out of a cheaper quote, so the saving is frequently not a saving.
Will any smart thermostat do?
No. It must have automation and optimisation to qualify. Confirm the specific model rather than assuming.
What is the 55°C rule?
A Part L requirement, separate from Boiler Plus, that new and fully replaced wet heating systems are designed for a maximum 55°C flow temperature. It affects radiator sizing.
Do I get paperwork?
Yes. A Building Regulations Compliance Certificate confirming the installation was notified, plus the benchmark commissioning record and warranty registration.
What to do about it
Get a quote that includes everything
Call 07514 312117 or send a WhatsApp. We tell you which measure is included and what the system is designed around, before you commit. Gas Safe registered 981362, CIPHE member, fully insured.