What temperature should a combi boiler be set at?

Nowadays, most newly built and updated homes are fitted with combi boilers. These systems get the combi name as they provide hot water for both the central heating and taps and shower heads. The additional duties lead some people to question what temperature is best for combi boilers to be set at, especially if they have moved into a new property. 

Below are our temperature recommendations for combi boilers. 

What does boiler temperature mean? 

When you see references to ‘boiler temperature’, it concerns the heat inside the boiler unit itself. This is an important distinction, as it is likely to be different from the temperature readings put out by thermostats around the property.  

Combi boilers utilise condensing technology to heat water to be used for keeping your home warm. Unlike regular boilers, a condensing boiler has an improved heat efficiency by making use of waste gases. This process involves the extraction of latent heat from flue gases in addition to heat generation through fuel burning.

Benefits of setting boiler temperature 

One of the main reasons you would want to set your boiler temperature is for heating efficiency. By their nature, combi boilers are already more efficient at heating than non-condensing boilers, with newer models able to reach over 90%. Although efficiency levels will vary between models, most non-condensing types will only reach 70-80% efficiency. 

This typically means just 10% of the heat that combi boilers will be lost, and the rest put to use heating your home. However, this efficiency can be compromised if the boiler is producing too much or too little heat. As combi boilers run on gas and electricity, the result is that your bills could increase unnecessarily. 

Boiler temperature can be adjusted depending on your property and the type of rooms. For instance, it’s recommended that less heat is allocated to bedrooms than other parts of the property. If your home has a separate thermostat for your bedroom, this can be set at a lower temperature while the boiler temperature remains the same. Heat efficiency can also be improved by setting a boiler timer, which you can get more information on here. 

Recommended set temperature for a combi boiler 

Unfortunately, there isn’t one size fits all when it comes to setting the best temperature for a boiler. Along with the potential influence of building factors, different makes and models can produce different levels of heat efficiency. Generally, the best way to guarantee boiler efficiency is to set the flow temperature as low as possible without removing heat from the property. Instead, below is advice from our expert in-house engineers on what internal temperature is best for a combi boiler. 

Central heating 

Modern combi boilers should be set at a flow temperature of between 60-70°C. This is the heat of the water intended for use in central heating and to be transported to radiators throughout the home. A temperature no higher than 70°C is recommended as any hotter will risk compromising the boiler efficiency by preventing the system from entering the condensing mode.  

In warmer months, boiler flow temperature can be reduced. Typically, 50-55°C is adequate to provide enough heat to your home. Certain home features such as thick carpets and double glazing, can enable this lower temperature to be effective during winter too as it helps trap heat. 

Hot water outlets 

The temperature for use in water outlets such as taps and showers can be set lower, at around 50°C. As cooling occurs in the time it takes for the water to reach the exit point, this temperature setting ensures the water doesn’t scald at the point of use. To guarantee avoiding this, you can set it slightly lower at 45°C. 

How to set combi boiler temperature 

When setting your boiler temperature, the first thing to do is to check the user manual. Most boilers have a control knob or dial that can be turned to adjust the working temperature.  As mentioned earlier, the boiler will not display room temperatures unless you have an internal stat fitted. Nevertheless, combi boiler heating temperature setting in modern units is usually done with a digital LCD screen. 

Using Viessman boilers as an example, the radiator outlet temperature can be altered by: 

• Finding the MODE button and pressing it. It should be on the front of the boiler unit. 
• Once the radiator icon flashes, select it by pressing OK. 
• You should now be able to change the temperature up and down in increments of 1°C with the arrow keys. 
• When you reach your desired temperature, confirm it by pressing OK again. 

The process is the same for adjusting the tap output temperature, except you should look for the tap icon at the first stage. If you’re having any issues with your boiler control interface, National Boiler Spares provides a range of branded boiler spares to help meet your needs. 

Delivered spare parts for boilers 

Many people have never considered if they need to adjust their boiler temperature settings. However, a comfortable heating level is essential to ensuring a good quality of life. With a boiler set to the right temperature, you’ll be able to heat your home to the desired temperature in a short space of time. If you suspect your boiler temperature is inaccurate or inefficient, don’t hesitate to contact us today. It could be costing you hundreds of pounds every month due to over-heating.