1. Turn down the boiler flow temperature

For combi boiler homes: quick win, good savings

What type of boiler it works for

✔ Combi boilers (As long as they are condensing — anything installed since 2005 almost certainly is.)
✘ Boilers that work with a hot water cylinder

Typical savings

• Around 7-8% for combi households.

Why it works:

Modern condensing boilers are designed to recycle waste heat to reach their advertised efficiencies, but this process can only happen the radiators are run a bit cooler.

Lowering what is called the 'flow temperature' from the boiler to the radiators helps it capture the waste heat and reduce gas use. Studies have found that most home stay warm at 60degC flow temperatures

2) Turn off the hot water 'pre-heat'

Most homes: quick win, decent savings

What type of boiler it works for

✔ Combi boilers (As long as they are condensing - anything installed since 2005 almost certainly is.)
✘ Boilers that work with a cylinder

Typical savings:

• Around 3-5% for combi households

Why it works:

Some combi boilers keep a small tank of water hot all day for quicker hot taps. This means the boiler fires regularly, even when you’re asleep or out.

Switching off pre-heat stops this constant burner cycling.

3) Reduce cylinder heating times

For homes with a cylinder: small effort, meaningful savings.

What type of boiler it works for

✔ Boilers that work with a hot water cylinder
✘ Combi boilers (they heat water on demand and don’t have a cylinder)

Typical savings:

• Around 2-4% for cylinder households

Why it works:

Most homes with a hot-water cylinder heat it for far longer than is necessary. Energy charities and independent advice are clear:

• You don’t need to heat hot water all the time, just heat it shortly before you need it.
• Timers exist so you can run the cylinder in short, targeted periods rather than continuous blocks.
• Most cylinders can reheat in 30–60 minutes, so long runs simply waste energy.

4) Turn down radiators in little used rooms

For most homes: quick win, low effort, meaningful savings

Who this applies to

✔ Homes with TRVs on radiators
✘ Rooms without TRVs (fixed valves)

Savings available:
If the average home turns down radiators in two rooms to around 15°C and keeps the doors closed, it typically saves 5–8% of total gas use for heating, based on the standard estimate that every 1°C reduction saves ~6% in that room.

Why it works:

Reduce the amount of floor space your boiler needs to heat will reduce your energy use.

What the numbers on your radiator valve mean:

• 1 ≈ 12–14°C
• 2 ≈ 15–17°C
• 3 ≈ 19–21°C
• 4 ≈ 22–23°C
• 5–6 = very warm (rarely needed)

5) Keep your existing boiler going

For most homes: quick win, zero disruption, big savings

Why type of home this works for:

✔ Any home with a working gas boiler
✔ Homes planning to switch to a heat pump later
✘ Homes with unsafe or irreparable boilers (rare)

Typical savings:

• Avoiding premature replacement saves £2,500–£4,000, plus yearly gas savings from simple optimisation.

Why it works:

Most boilers are retired long before their time. Although modern models can run for 18–22 years, about 75% of UK households have boilers under 12 years old, so many are replaced halfway through their lifespan.

To make matters worse, replacing early rarely saves money. Most homes already have a top efficiency A-rated boilers, so a new A-rated boiler one won’t lower bills enough to justify the upfront cost.

The smarter option is usually to keep the boiler you’ve got. Parts remain widely available for older models and a servicing plan or maintenance contract is typically 35–55% cheaper over a decade than fitting a new boiler.