Last updated on January 2nd, 2025
Are you wondering what the ideal temperature settings for your combi boiler should be? Setting it too high can waste energy and drive up costs, especially with rising UK energy prices, while setting it too low can leave your home feeling chilly. As a heating engineer with over a decade of experience repairing and servicing combi boilers, I’ll share the most efficient settings to keep you warm and your gas bills low.
Heating temperature setting
The heating temperature settings on a combi boiler can be adjusted in two places, at the boiler itself and at the room thermostat. The boiler controls the temperature of the water circulating through your radiators, while the thermostat controls the overall temperature of the room and home.
What’s the optimum temperature to set?
The ideal temperature setting for your combi boiler can vary depending on its size, system setup, and your home’s needs. However, for most combi boilers, a good starting point for heating is 65°C.
If your home isn’t warming up quickly enough, try turning it up slightly. On the other hand, if the radiators feel too hot to touch and you’re concerned about safety, especially with kids or pets around, you may want to lower the temperature a bit.
When it comes to your thermostat, most people find 19-21°C comfortable. That said, it’s a personal preference, and the lower you can set it while staying comfortable, the more energy and money you’ll save.
How to set the flow temperature
Setting the heating flow temperature on a combi boiler is usually very straightforward. Most combi boilers have two dials (though some may have only one). Look for the dial with a radiator icon, which controls the heating. Simply turn this dial until you reach your desired heating temperature setting.
If your combi boiler doesn’t show actual temperature numbers, setting it to around two-thirds of the maximum is usually ideal for the flow temperature. Some boilers also have an ‘E’ setting, which typically indicates the most energy-efficient option, use this if available.
If your boiler doesn’t have dials, it may have buttons instead. Simply press the up or down buttons to adjust the flow temperature to your desired setting. If you’re unsure how to operate it, refer to your combi boiler manual for guidance.
Hot water temperature setting
The temperature setting for hot water doesn’t significantly affect gas usage, as the hot water isn’t on for long periods like central heating. Showers and taps usually mix hot and cold water, so it’s better to set the hot water temperature on the boiler a bit higher rather than too low.
If the water is too hot, you can always adjust the temperature at the tap or shower, but if it’s set too low at the boiler, you can’t increase it once it’s running. Keeping the boiler’s hot water temperature at a reasonable level ensures you’re not wasting energy while also having the flexibility to control the temperature at the tap.
What temperature should the hot water be set at?
The standard temperature for hot water is around 55°C. If this isn’t hot enough for your needs, you can increase the temperature on your boiler. Conversely, if the water is too hot, simply turn it down to a more comfortable level. Adjusting the temperature ensures you have the right balance of comfort and energy efficiency.
How to use a combi boiler efficiently
If you don’t have a room thermostat, it’s highly recommended to install one. Operating your heating without a thermostat can lead to inefficiency and higher energy use. The combi boiler’s heating temperature controls the radiators, while the room thermostat regulates the temperature of the room, ensuring comfort without overheating.
The hotter you set the combi boiler’s heating temperature, the hotter the radiators will be, and the quicker the room will heat up. However, if the room thermostat is set to 20°C, it will turn off the heating once the room reaches that temperature. When the room cools below 20°C, the heating will come back on to maintain the desired temperature.
While raising the boiler’s temperature will make the room reach 20°C faster, the room will never exceed the thermostat’s setting. Even if the boiler’s temperature is set to 80°C, the room will only reach the temperature set on the thermostat.
Condensing boilers
Keep in mind, setting the combi boiler to maximum will heat your home faster, but it will also increase gas usage. If you have a condensing combi boiler, setting it too high will prevent proper condensation, reducing efficiency.
Summary
With gas prices so high, getting your combi boiler temperature settings right is essential. If you have thermostatic valves on your radiators, lower them in rooms you don’t use often to save gas. Finding the right balance, where your radiators aren’t too hot or too cold, is key for efficient heating during the winter.
Have any questions? Drop them in the comments below, I’ll do my best to help! If you found this post helpful, don’t forget to share it with others who might benefit.
FAQs
Should radiators be too hot to touch?
Radiators can be too hot to touch and quite often are. If you have small children in your home regularly, then having the radiators too hot to touch is probably a bad idea. You can turn the temperature of your radiators down at the boiler by turning the dial with the radiator symbol down or you might have to press a button.
Why are some of my radiators hotter than others?
Some of your radiators are hotter than others most likely because you need to balance the radiators. You might need to flush your central heating system also, but most of the time when some radiators are hotter than others it’s down to them needing to be balanced.
Does turning the boiler temperature down save money?
Yes, turning the boiler temperature down will save money. Whether it’s turning the room thermostat down (which will mean the boiler isn’t on as much) or turning the radiator temperature down on the boiler (which means the boiler won’t be working as hard) both ways will save gas and therefore money!
I set my tap hot water temperature on my combi boiler to 50°c, but the water gets much hotter than that setting and when the heating is on the water is almost scalding hot.
Can you advise me on what I should do about it please?
Thank you.
I have tried adjusting and resetting my water temperature on my boiler but for the last several days it’s showing as 20° and switches in when u reset it but it won’t go any higher despite being set to 65°. What should I do?
When I set the radiator temperature say to 50°C using the up/down buttons. The displayed temperature (and I presume the radiators) are much hotter 70-80 °C. Why is this? The temperature sensor is working as it is giving a (too high) reading so why does the “software” not turn down the heat? It is a Baxi combi 124-128.
Yeah if you’ve set the heating temperature setting to 50 and it’s actually 70+ then you have a problem. Potentially gas valve or PCB.
I’ve figured it out. The numbers that come up when I press the “radiator buttons” is actually a temperature profile (based on the external temperature) not the boiler temperature. So if it’s minus outside almost ant setting will take the radiators up to 85° . Why do these things have to be made so difficult?
The temperature setting controls are definitely getting more complicated and annoying on some boilers and thermostats, I think it’s down to trying to make them as energy efficient as possible.
Maybe as they have put a microprocessor in there and employed a software engineer. They need to think of new and exciting things to add to what should be a basic function device.