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Best Settings for Your Worcester Combi Boiler

For most homeowners in the UK with no more than 2 bathrooms in their properties, the Combination (Combi) boiler is the most popular boiler installed in the UK. Worcester Bosch is also the most popular boiler brand in the UK, so we thought it would make sense to outline what the best settings are to warm your house, heat water and improve efficiency.

We’ll be going over the optimal settings for both your hot water and central heating needs. We’ll also look into controls and features such as Load Compensators and Wireless Plugin Controllers which not only save you money, but are good for the environment, too. Let’s look first then at the settings for your central heating system using a Worcester Bosch combi boiler.

Settings for Your Central Heating System

With a Worcester Bosch Combi boiler, you have the advantage of controlling the period you want the radiators to be working (based on a 24-hour clock system). This means that you can regulate your radiators to go off when you’re not at home, and then program the thermostat to increase the temperature when you are around. 


During the winter, the ideal temperature setting should be 18-21°C. In areas that get extremely cold, then 21-23°C would be sufficient. If you’ve taken additional measures to retain heat, such as wall insulation or draught-proofed windows and doors, then you could set your thermostat to 17°C.


It might not seem like much but according to Worcester News, reducing the temperature by just a single degree celsius could result in heating bill savings of up to 10%, not to mention the environmental benefits this would have.

It’s important to note that your thermostat temperature for your central heating is not the same as the appropriate boiler temperature. For the correct central heating setting on the boiler itself, jump to the section: Worcester Bosch Settings 1 to 6

What Temperature Should Hot Water be Set (Combi Boiler)

For your hot water needs, we recommend setting your Worcester Bosch boiler at 55–60°C which is sufficient for most homeowners in the UK. Generally speaking, combi boilers don’t come with a hot water cylinder as they heat water on-demand, however some larger boilers might have a storage component. This temperature would be ideal to eliminate the presence of Legionnaires Disease, a form of Pneumonia caused by bacteria in the water.

Most Economical Settings For Combi Boiler

Typically, the most economical and efficient setting for your combi boiler is to set your hot water temperature to 60°C and your central heating temperature (within the boiler, itself, also known as the flow temperature) to 70-75°C. This is the ‘sweet spot’ in terms of giving you what you need, heating and hot water-wise, without being overly expensive or energy-intensive.

Worcester Bosch Boiler Settings 1 to 6

On Worcester Bosch boilers like the Greenstar Si, both the central heating and hot water temperatures are controlled using dials on the boiler’s front panel. Both of these dials are numbered 1 to 6. 


To set the right Worcester Greenstar boiler water temperature settings – around that 60°C mark – set the hot water dial to setting 3. For the correct central heating flow temperature, set the heating dial to setting 4 or 5. To find out which temperature all the settings correspond to, view the Greenstar Si manual.

How to Reduce Water Temperature on Worcester Boiler

Simply find the hot water dial on the front panel of your Worcester Bosch boiler (it will have settings going from 1 to 6) and lower it down one level. If, on the other hand, your Worcester boiler’s water isn’t hot enough, then turn up the hot water dial by one setting. This should easily give you hot enough water.

Best Settings for Worcester Bosch Smart Devices

Worcester Bosch Boilers come with highly advanced smart devices which enable you to program your boiler, even when you’re not around. Some of these devices can adjust the settings of your boiler; this is done through wireless communication between the thermostat and a corresponding temperature sensor.

Ideal Settings for Programmable Room Thermostats

When it comes to making savings on your energy bills, programmable room thermostats are amongst the best options out there to help you. For one, they allow you to heat a house from a reasonable temperature (rather than a cold start). This is preferable because we’re sure that most homeowners can relate to the long waits in the winter as the house warms up. 


These thermostats also ensure that your boiler reaches the maximum temperature you had set it at. If you had set your temperature at 21°C, for instance, then your central heating will cap off at that temperature. Lastly, room thermostats allow you to set the ideal temperature of a particular room.


If, for example, there’s a room in your home that’s used only occasionally, then you could set the thermostat at a lower temperature for that particular room. If the rest of the house is set to 20°C, then the empty room should be set to 10°C. If you adopt this strategy, then ensure that you keep the door firmly closed to retain heat elsewhere in the home.

Ideal Settings for a Mechanical RF Thermostat

Worcester Bosch boilers utilise the Worcester MT10RF as its Mechanical Room Thermostat. The MT10RF allows you to control the temperature of your central heating during the day and at night. The central heating comes on (and turns off) based on the time settings you’ve programmed for both the day and night. 


During the day, you could set your Worcester Combi Boiler at a temperature of 6 to 8°C if you’re not home. At night, when you’re nice and covered up, then you can consider lowering the temperature to 14 or 15°C.

Best Settings for a Worcester Bosch Wave System

This is another invaluable control on Worcester Bosch boilers which enables you to regulate your central heating and hot water from anywhere around the world. That means, if you’re away on your summer holidays you can be safe in the knowledge that you can still control your boiler’s settings.

Based on heating and hot water charts, the system allows you to regulate your home’s temperature, and therefore save on energy bills – something which is particularly important at the minute. 


The system also enables your Worcester Bosch Greenstar Combi boiler to achieve an A+ efficiency rating. With the system you can also activate holiday mode which ensures your boiler is running just enough to prevent the valves and other components from seizing up. During the winter, it would be best to set your thermostat at a minimum temperature of 5°C to prevent the boiler and pipework around your home from freezing.

Ideal Settings for a Weather Compensation Controller

Weather Compensators work alongside an outdoor sensor monitoring the weather. It’s quite similar to a load compensator, except that with weather compensators, the outdoor sensor monitors external temperatures.


When the temperature outside drops, your central heating increases its output to produce more heat. Conversely, when the temperature increases, the central heating output is decreased. 

Worcester Bosch boilers come with a highly advanced Greenstar Sense II compensator. As a thermostat, Greenstar Sense comes with six settings that enable users to tailor their heating system according to their needs. The controller can potentially increase energy efficiency by as much as 4%.

Load Compensation Controls

This is another valuable control that can help you significantly save on your energy bills. Load compensators work by regulating the radiator output in a room. If the temperature in the house decreases, the radiators will increase their output and release more heat. When the temperature in the house goes down, the radiators decrease their output and release less heat.


Ultimately, the best settings for your boiler depends on your central heating and hot water needs. Having a thermostat at a temperature ranging between 18 to 23°C and hot water ranging between 55 to 60°C gives you a ballpark estimate of what you’ll want to set your boiler to.


You can also improve the efficiency of your boiler with other controls such as Programmable Room Thermostats and Weather or Load Compensation controls. Increasing the efficiency of your boiler not only saves you money but your boiler becomes more eco-friendly, too. Something which we’re all looking to improve upon in the midst of a global climate crisis.