What are the Most Economical Settings for a Combi Boiler?

Key Takeaways

  • Optimising combi boiler settings can lead to substantial savings on energy bills. The most economical temperature for a combi boiler is between 60℃ to 65℃.
  • The most efficient setting varies with different factors such as insulation, external temperature and the age and model of the boiler.
  • Making use of advanced boiler features like heating schedules, priority hot water kits and modulation can help improve boiler efficiency.
ℹ️ Good care and maintenance will help save money on your heating bills over time by ensuring your boiler is always operating at peak efficiency. When was the last time you had your boiler serviced?

Understanding the Different Settings on a Combi Boiler

A combi boiler is an integral component of many homes, providing both heating and hot water. These boilers have several settings that help you control the efficiency and performance of the system. The settings typically found on a combi boiler include:

Temperature Setting

This controls the temperature of the water that is heated and sent to the radiators and taps.


Modern boilers can adjust their output depending on the heat demand, which makes them more efficient.

Heating Schedule

Allows you to set specific times for the boiler to heat up, optimising energy usage.

Hot Water Priority

This function prioritises the delivery of hot water over central heating.

What to know about “Turning Your Boiler Down”

turning boiler down

A common misconception is that having your boiler temperature set high will warm up your home quicker. However, this isn’t always the case. A more economical and efficient approach is to have your boiler run for longer periods at a lower setting.

Understanding Flow Rates

The ‘flow temperature’ refers to the temperature of the water as it leaves your boiler to circulate through your radiators. A common issue with many boilers is that they operate at flow and return temperatures of 80/60°C, which is far from optimal for a condensing gas boiler. 

To achieve the highest possible efficiency, you should aim to operate your boiler in ‘condensing mode’, which requires temperatures of 70/50°C or less. Peak efficiency is typically achieved when the flow temperature is 60°C or lower.

Detailed Efficiency Optimization for a Combi Boiler

Mode Flow Temperature Return Temperature Flue Gas Temperature Efficiency Remark
Regular Mode 80°C 60°C > 120°C Less Efficient Traditional operating mode, not utilizing condensation heat
Condensing Mode <= 70°C <= 50°C < 120°C Highly Efficient Utilizing condensation heat, can save more energy
Peak Efficiency <= 60°C <= 40°C < 120°C Most Efficient This mode ensures maximum efficiency of the boiler

Detailed Efficiency Optimization for a Combi Boiler

Adjustment Before After Impact on Efficiency Resulting Mode
Lower Flow Temperature 80°C <= 70°C Increased Condensing Mode
Lower Return Temperature 60°C <= 50°C Increased Condensing Mode
Lower Flow & Return Temp. 80°C/60°C <= 60°C/<=40°C Greatly Increased Peak Efficiency Mode

Adjusting Flow Rates

The flow rate measures the volume of water that can flow through your system per minute. To adjust the flow rate on your combi boiler:

  • Locate the flow rate adjuster, typically a dial or knob.
  • Turn the adjuster clockwise to increase the flow rate and anticlockwise to decrease it.
  • Make minor adjustments and monitor your boiler’s performance to find the optimal flow rate.

Finding the Optimal Temperature Setting

finding the optimal temperature setting

The optimal temperature setting for your combi boiler depends on your home’s specific circumstances, including how well insulated it is, the external temperature, and the boiler’s age and model. 

A temperature setting of around 60℃ to 65℃ is typically sufficient for most homes. This level efficiently heats your home without wasting energy. Reducing your boiler temperature doesn’t mean your home will be cooler; it means your boiler operates more efficiently and uses less energy to reach the desired temperature.

Combi Boiler Settings to Save Money

combi boiler settings to save money

To maximise the efficiency of your combi boiler, you can adjust certain settings. Here’s how:

Considering a Heating Schedule

A heating schedule, or heating timer, provides several benefits when used with your home’s heating system. It allows you to program your heating system to turn on and off at specific times, aligning with your daily routines and needs.

This can greatly enhance comfort and convenience while also saving energy and reducing costs. Here are the main benefits:

Energy Efficiency

By only heating your home when you need it, you can avoid wasting energy on heating when nobody is home or everyone is sleeping. This can significantly reduce your energy consumption and thus your carbon footprint.

Cost Saving

Reduced energy consumption also leads to reduced utility bills. According to some estimates, properly using a heating schedule could save you 10% to 30% on your heating costs.


A heating schedule ensures your home is at the right temperature when you need it to be. For example, you can set it to heat up your home just before you wake up or return from work, so you always come to a cosy, warm environment.


Once set, the heating schedule operates automatically. You don’t have to remember to turn the heating on or off, nor worry about coming home to a cold house.


Most heating schedules allow you to set different temperatures for different times of the day and different days of the week. This means you can tailor your heating to your specific needs and routines.

By efficiently managing when and how much heating is used, a heating schedule is a great tool for maximising comfort while minimising energy consumption and costs.

Don't let your energy bills soar due to a poor maintenance.

Contemplate Using a Priority Hot Water Kit

A Priority Hot Water Kit is typically an addition to a heating system that allows the domestic hot water (DHW) to be prioritised over the central heating system. Essentially, when there’s a demand for hot water (like when someone opens a hot water tap or a shower), the priority hot water kit signals the boiler to momentarily suspend the central heating and prioritise heating the water for immediate use.

This system is especially useful in peak usage times when you might need immediate hot water but don’t necessarily need to be heating the whole house, like in the morning when people are typically showering and getting ready for the day. 

It can help ensure there’s always enough hot water when you need it, without having to continuously heat a large volume of water, hence saving energy. Remember that the specific design and functionality can vary between different manufacturers and models of boilers, so it’s always best to refer to the manual or consult with a professional.

Modulation Settings

Adjusting the modulation settings of a combi boiler should be done by a qualified professional. This is because these settings can have a significant impact on the operation, efficiency, and lifespan of your boiler, and improper adjustment could lead to inefficient operation, increased energy usage, or even damage to the boiler.

The modulation settings control how the boiler adjusts its output in response to changes in demand. When demand is low, the boiler can reduce its output to save energy, and when demand is high, it can increase its output to ensure sufficient heating or hot water supply. 

Here are the general steps a professional would take to adjust the modulation settings:

  1. Access the Boiler’s Settings: The technician would access the boiler’s settings, usually by navigating through the boiler’s control panel or digital interface.
  2. Locate the Modulation Settings: The modulation settings are usually located in a specific section of the boiler’s settings. The exact location will depend on the model of the boiler. The user manual or technical guide should provide specific instructions.
  3. Adjust the Modulation Settings: The technician would adjust the modulation settings to the desired levels. This could involve increasing or decreasing the maximum and minimum output levels, adjusting the rate at which the boiler modulates its output, or making other adjustments depending on the boiler’s features and capabilities.
  4. Test the Boiler: After adjusting the settings, the technician would test the boiler to ensure it is operating correctly. This would typically involve running the boiler and monitoring its operation to ensure it is modulating its output correctly in response to changes in demand.

Again, it’s important to reiterate that adjusting these settings should be left to professionals. If you’re experiencing issues with your boiler, or you think it could be operating more efficiently, we recommend contacting a certified HVAC professional for assistance.

Frequently Asked Questions (FAQs)

What is the Most Economical Temperature for Central Heating?

The most economical temperature for central heating is generally between 60℃ and 65℃. This setting allows your boiler to heat your home effectively without wasting energy.

What is the Most Efficient Way to Run a Boiler?

The most efficient way to run a boiler is to keep it at a steady temperature, use a heating schedule, enable modulation, and use a priority hot water kit if available. Regular servicing and maintenance are also important for ensuring boiler efficiency.

Does Turning the Boiler Down Save Money?

Yes, turning down your boiler temperature can save money. Lowering the temperature allows the boiler to operate more efficiently and use less energy. However, the boiler may need to run for longer periods to heat your home to the desired temperature.


The most economical settings for a combi boiler can vary depending on a range of factors but in most cases you want a temperature of 60℃ to 65℃ (flow rate of 70/50°C). However, by understanding your boiler’s settings and optimising them, you can achieve significant savings on your energy bills without compromising the comfort of your home. If your boiler is due for its annual service and you’re in London please do get in touch.

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