What Temperature Should My Boiler Be Set At?
What Temperature Should My Boiler Be Set At?
The temperature settings on a boiler can be confusing. It’s not always immediately obvious what the settings do, and it’s also not always clear what the best settings are.
Different boilers work in different ways, and you need to understand how your boiler works before you adjust the settings. The ideal settings for your home also depend on quite a few factors. You need to consider factors like what type of heating system you have, how well insulated your home is or how hot you want your tap water to be.
The settings on your boiler also have a big effect on how well your whole heating and hot water system works. They control how warm your home is as well as how efficiently your heating and hot water operates. You could save money on your energy bills and prolong the life of your boiler by finding efficient boiler temperatures that still effectively warm your house.
In this article, we’ll explain how boiler temperature settings work for the main types of domestic boiler in the UK. We’ll explain what temperature your boiler should be set at for central heating in the UK and what temperature it should be set at for hot water.
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What temperature should my boiler be?
Before you try to adjust your boiler, take the time to understand how boilers work.
Boilers produce hot water for your heating system and for the showers and hot taps in your home:
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Flow temperature – This is the temperature of the water your boiler supplies to your heating system.
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Hot water temperature – This is the temperature of the hot water your boiler supplies to the taps and showers in your home.
Combi boilers work by taking cold water from the mains, heating it and immediately supplying it to either your heating or hot water system. In a combi boiler, you have separate settings for heating and hot water.
System boilers and conventional boilers work with a hot water storage tank. Hot water is stored in a tank and supplied to both your heating and hot water systems from the tank. When hot water is stored in a tank it must be kept at a minimum of 60°C to prevent legionella bacteria from growing in the tank. For this reason, you normally can’t adjust either the flow or hot water temperature below 60°C on a system or conventional boiler.
You will only have separate control for flow and hot water temperatures on a system or conventional boiler if it has been adapted to allow this.
What settings should my combi boiler have?
Before you adjust the settings on your own combi boiler, make sure you look at the user manual. Optimal settings vary from boiler to boiler. It’s always a good idea to check the manual for tips.
Combi boilers are an efficient and space saving modern choice of boiler.
On a combi boiler, you have separate settings for flow and hot water temperature.
Flow temperature
This is the temperature of the water that flows to your radiators or underfloor heating.
For efficiency, it’s generally better to aim for reduced flow temperatures that still effectively heat your home. The best settings, however, depend on the type of boiler, the type of heating system you have and factors that affect heating efficiency, like the weather or how well insulated your home is.
You also shouldn’t lower the flow temperature below what a boiler and heating system is designed to operate at.
Hot water temperature
This is the temperature of the hot water that flows to your showers, baths and taps.
Combi boilers do not store hot water in a tank, making it possible to lower the temperature below 60°C to reduce the risk of scalding.
What temperature should a combi boiler be set at?
Here are some guidelines on what temperature a combi boiler should be set at for flow temperature, and what temperature it should be set at for hot water.
Flow temperature:
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General range: 50 - 60°C
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Condenser combi boilers: 50 - 55°C
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For underfloor heating: 35 - 55°C
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Old, less well insulated homes and homes with old heating systems: 60 - 65°C.
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In very cold weather: 60 - 65°C
Always make sure you check what temperature your boiler is designed to operate at before you change the settings.
If you want to reduce the flow temperature on your combi boiler for more efficiency, you can try. Be aware, however, that this will mean your house will heat up more slowly or won’t heat up properly if you set it too low. Elderly residents or people with health conditions could be affected by cold temperatures.
Normally, you should aim to find a reduced flow temperature that your boiler can operate at and which still effectively powers your heating system. You’ll probably need to adjust the settings a few times to find the right flow temperature to adequately heat your house.
What temperature to set a combi boiler at for hot water:
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Around 50°C
It’s best to reduce your hot water to around 50°C to avoid the risk of scalding if you live with children, elderly people or anyone else who’s at risk.
What temperature should my boiler be set at for central heating?
You cannot adjust the temperature below 60°C in a system or conventional boiler with a hot water storage tank unless it has been adapted to allow it. Normally, only combi boilers have a separate adjustable flow temperature for central heating.
The correct temperature to set your boiler at for central heating depends on what heating system you have and your model of boiler. As well as this, how well insulated your home is and how cold the weather is also have a big effect.
Different boilers are designed to work in different ways, and you should find out what temperature ranges your boiler is designed to operate in. You should also find out what ranges it works most efficiently in. If you have a condenser boiler, for example, it will work more efficiently at lower temperatures. Condenser boilers are normally most efficient at around 50 – 55°C.
Different heating systems also work optimally with different flow temperatures. Underfloor heating systems normally work at 35 - 55°C, which is a much lower temperature than radiators, for example. Modern heating systems, including smart heating systems, also work at lower temperatures than older systems.
The quality of the insulation in your home and the weather also have an effect on how much you can lower the flow temperature on your boiler before your heating becomes ineffective.
What temperature should my boiler be set at for hot water?
The best temperature to set you boiler at for hot water in the UK depends mainly on what type of boiler you have.
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System boilers and conventional boilers – The hot water should always be kept at a minimum of 60°C. This will stop dangerous bacteria from growing in the tank.
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Combi boilers – You can adjust combi boiler hot water temperature below 60°C without the risk of disease. Around 50°C is a good temperature to reduce the risk of scalding from hot taps.
How to set your boiler temperature
The way that you adjust the temperature on a boiler depends on the model of boiler. Most boilers have a central control panel for adjusting the settings. The best thing is to look in the manual for information.
Combi boilers have two separate settings for flow temperature and hot water temperature, and it’s often easy to adjust the settings:
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Step 1. Look for two separate controls labelled ‘heating’ or ‘hot water’ or with a radiator or tap icon to indicate what the settings adjust.
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Step 2. Adjust the temperatures.
System and control boilers have various different controls. If your system or conventional boiler has a single control for the hot water storage tank control, do not adjust the temperature below 60°C for safety reasons.
Did you know that heat pumps are a modern alternative to conventional boilers. Find out how heat pumps work to provide an alternative eco-friendly heating solution.
What is the boiler flow temperature?
The flow temperature on your boiler is the temperature at which water leaves your boiler and is supplied to your home’s heating system.
The flow temperature is important because it has a big effect on how powerful your heating system is and how hard your boiler has to work. The higher the flow temperature, the faster your home will heat up and the warmer it will get. This will cost more on your energy bills, however, and it will mean your boiler has to work slightly harder.
You can try to find an economical flow temperature that effectively heats your home. The flow temperature on your boiler is separate to the controls on your heating system like your main thermostat or thermostatic radiator valves (TRVs). These still operate in the same way if you adjust the flow temperature, although your heating system will not be able to work properly if the flow temperature gets too low. The temperature that water returns from your heating system to your boiler is called the return temperature.
Should I turn my boiler’s flow temperature down?
You can turn your boiler’s flow temperature down as long as your boiler is designed for this. All combi boilers allow you to turn the flow temperature down but you should always check what temperature a combi boiler should be set at before you adjust it.
By turning the flow temperature down, you might be able to find more efficient settings for your boiler. This could reduce your energy consumption and save you money on your fuel bills. It could also prolong your boiler’s life.
Just be aware that you still need your boiler to heat your house properly. Lowering the flow temperature could make it take longer to heat your house, or it might mean it doesn’t heat up properly at all. You also need to adjust the flow temperature to suit the type of heating system you have.
It’s important to consider how your heating system functions. Radiators, for example, are manufactured with a BTU rating. This indicates how much heat a radiator can deliver to a room. Radiators are designed to operate at their BTU rating when they are matched with a boiler that provides specific flow temperatures. Changing the flow temperature may mean your heating system has to work with a temperature below what it needs to work to full capacity.
How do I lower my boiler flow temperature?
The way you lower your boiler’s flow temperature depends on the type of boiler you have. Combi boilers often have a display with a setting that reads ‘heating’ or which features a radiator icon. You can adjust this to lower your flow temperature.
Be careful not to adjust the temperature too low. It’s possible that your heating system won’t work fully either immediately or in the future if the weather gets colder. Be careful if you live with elderly people or people with health conditions.
Will lowering my boiler flow temperature mean lower fuel bills?
Lowering your flow temperature to find the most efficient settings could save you money on your fuel bills. It’s not clear how much people can save, and savings will differ from household to household. You can, however, save money. Some sources claim you could reduce energy use by as much as 10%, although real figures are likely to be lower.
You can also look at other ways to cut your energy use. You could turn your thermostat down instead. As well as being effective, this is much easier than adjusting the flow temperature and you won’t adjust your heating system below its normal operating temperature.
Adding some simple smart home heating devices is a great way to cut your energy use. Smart thermostats and smart TRVs are great, simple devices that can help cut your energy use.
What are the risks if I turn my boiler’s flow temperature down?
You should not turn the flow temperature down in a system boiler or a conventional boiler with a hot water storage tank unless it has been adapted to allow it. Hot water held in storage tanks must be stored at a minimum of 60°C.
You can only adjust the flow temperature below 60°C in combi boilers and other boilers that are designed to allow it.
If you turn your boiler’s flow temperature down too low, it might mean your heating system doesn’t work properly. It might heat your house up too slowly or it might not be able to heat your house up properly at all. This could happen immediately after you lower the temperature, or it could happen in the future when there’s a drop in temperature.
You could also damage your boiler if you lower the temperature lower than it is designed to operate at. You should always consult the manual to find minimum operating temperatures.
Boiler temperature key takeaways
This article should have helped to guide you on what temperature your boiler should be set at for heating and hot water in the UK. Before you adjust the settings on your boiler make sure you understand how your boiler works. Different types of boiler are designed to operate in different ways, and they should only be adjusted according to how they are designed to operate. The settings on your boiler also need to be matched with your heating system as well as factors like the weather and how well insulated your home is.