What temperature should my boiler be in winter?

Key takeaways

• Set the flow temperature between 60ºC and 70ºC for effective heating in winter, and lower it to 50ºC to 55ºC in milder weather.

• Adjusting boiler temperature can save 9% to 13% on energy bills while maintaining a warm home.

• Adjust boiler settings before winter and consider summer servicing for peak efficiency.

With the right boiler temperature settings, you can strike a balance between cosy warmth and managing your energy costs. The correct boiler temperature is crucial for maintaining a comfortable, cost-effective and energy-efficient home environment throughout the colder months.

What is the optimal combi boiler temperature setting?

The flow temperature is the temperature that a boiler heats water before sending it through your central heating system.

On modern combi boilers, you can set different flow temperatures for your radiators and your hot water. By default, these are higher than you need, so adjusting the settings can cut your energy consumption and save you money – while also keeping your home perfectly warm.

If your home is well-insulated, you can push your flow temperature even lower. You can make your home more energy efficient by:

• Installing cavity wall and loft insulation

• Upgrading your windows from single-glazed to double-glazed (or even triple-glazed)

• Draught-proof windows and doors to prevent heat escaping

Bear in mind, though, that everyone’s house and heating system is different. Make sure that the temperature you set is comfortable and not too cold.

If you have a health condition and need to stay warm, we'd recommend leaving your boiler settings alone to avoid risking your wellbeing.

For your hot water needs, a safe and practical setting for a combi boiler is around 50ºC. This temperature is adequate for domestic use, ensuring that the water is hot enough for baths and showers while also preventing the risk of scalding. If you're diluting your hot water with cold water when running a bath or shower, it's probably set too high.

How much can I save by lowering my boiler's flow temperature?

Turning boiler temperatures down does save money, with the Energy Saving Trust suggesting savings of around 9%.

When to adjust boiler temperature

Adjust your boiler temperature before the cold really sets in. Ideally, you should start using your heating system when indoor temperatures begin to dip to uncomfortable levels, based on personal preference and concerns about energy costs. While alternatives such as electric blankets can provide some relief, a properly heated home is essential, particularly during extremely cold weather.

Moreover, to ensure your boiler operates at peak efficiency, consider having it serviced during the summer months. It’s always worth paying to have your boiler serviced when demand is lower, and you can ensure it's in top condition for when you need it most.

Additionally, many boiler cover plans include a free annual service to keep your boiler in tip-top shape.

How do I adjust the temperature of a combi boiler?

Combi boilers have a control that you can directly adjust to set the temperature. This could be a physical dial or slider, or a digital display panel. You’ll typically have two separate controls: one for the tap, and the other for any radiators.

It’s quick and easy to control the flow temperature yourself, and you can change it anytime. If you’re unsure how to do so, consult your combi boiler’s user manual, or get in touch with a qualified professional.

How do I adjust the temperature of a system boiler and hot water cylinder?

Typically, these have a single control dial that regulates both heating and hot water flow temperature. The HSE recommends storing the water above 60ºC to control the risk from legionella, while the Heating Hub suggests keeping flow temperatures at 70ºC to compensate for heat losses when hot water is being transferred from the cylinder.

Do not adjust the settings on a system boiler or hot water cylinder yourself. This is because unlike combi boilers, system boilers have a hot water cylinder which requires specific settings and hotter temperatures to maintain health and safety guidelines.

Instead, you should get a qualified professional to visit and confirm the flow temperature that should be set for your hot water cylinder.

Energy saving measures for hot water cylinders

• Insulate your hot water cylinder with jacket insulation

• Add radiator reflector panels behind your radiators

What else can I do to save money on my energy bills?

• Invest in a smart thermostat

• Upgrade older and inefficient boilers

• Review your appliances and check how much they're costing to run

• More energy saving tips

• Switch to a new energy tariff if you're paying too much