As the warmer months settle in across London, many homeowners ask the same question: should you turn off your boiler in summer? It might seem like a quick way to save energy—but before switching it off completely, there are a few things you should consider. 

As the warmer months settle in across London, it’s natural for homeowners to wonder: “Should I turn my boiler off completely during summer?” It might seem like a simple way to save energy—but before flipping that switch, there are a few important things to consider.

At DL Gas & Maintenance, we get asked this every year, so here’s our expert breakdown of what you should do (and avoid) to keep your heating system safe, efficient, and ready for when autumn rolls around.

Why some people switch their boiler off completely

If you’re not using your central heating and have an alternative way to heat your water (like an electric immersion heater or solar thermal), turning your boiler off can make sense. It reduces gas usage, stops any unnecessary wear on internal parts, and can slightly cut your bills.

However, most modern households—especially those with combi boilers—still rely on the boiler for daily hot water, even in summer. That’s why it’s not always as straightforward as turning it off completely.

The smarter option: Summer mode or hot-water-only setting

If your boiler has a summer mode or a hot-water-only setting, we recommend using it instead of turning the system off fully. This disables the central heating function but still keeps your hot water flowing when you need it.

For most of our customers across Bow, Canary Wharf, Eltham, Sidcup, Hackney and Dartford  this is the ideal solution. It saves energy while avoiding the risks associated with letting your boiler sit completely idle.

Should you turn your boiler off in summer? Here’s what can go wrong

• Pump seizure – If your central heating pump isn’t used for months, it can seize up and stop working properly. Running the heating for 5 minutes every few weeks can prevent this.

• Display or control panel faults – Some older models can experience issues when powered down for long periods.

• Smart thermostat disconnection – Turning off your boiler at the mains can cause your smart heating controls to lose connection or reset.

• Legionella risk (for cylinder systems) – If you have a hot water tank, it needs to be heated to at least 60°C regularly to prevent bacterial growth. Leaving it completely cold for weeks isn’t safe.

Our engineer-approved summer boiler checklist

To keep things running smoothly over summer, our experts recommend:

• Use your boiler’s summer mode (or hot-water-only function)

• Lower the flow temperature to 55–60°C for efficiency

• Run the heating briefly every 2–3 weeks to prevent pump problems

• Book your annual boiler service in July or August—before the cold rush begins

• Switch off any unnecessary timers or heating schedules that may still be active from winter

Need professional help this summer?

DL Gas & Maintenance offers:

• Annual boiler servicing (ideal to book before autumn)

• Combi boiler upgrades and replacements

• Repairs and diagnostics if your system isn’t performing as it should

• Gas fire installation and servicing so your system runs efficiently year-round

We cover homes and properties across East and South East London, including Bow, Hackney, Eltham, Sidcup, and Canary Wharf.

Book your summer service today

Let our Gas Safe registered engineers help you keep your boiler in top condition. Whether you’re planning a full switch-off or just need some energy-saving tips, we’re always here to help.

Call us today on 020 3983 8090 or book online here to secure your summer appointment.