Radiator Buying Guide
Choosing the right radiator type can be complicated when so many heating options are available. Luckily, this radiator buying guide covers all the information you need to buy an efficient new radiator.
When you’re buying a radiator, there are so many things to consider. These include the room size you want to heat, the radiator style, the required BTU (British Thermal Unit) output, and the heating type that best suits your home. This guide focuses on various wall-mounted radiator options, explaining how they work to help you choose the best one for your property. As this guide is lengthy, feel free to use the contents below to jump to the section you need.
What size radiator do I need?
Before we get into the different radiator types available, it's best to know what size radiator you need to heat your room. The size of the radiator will be dependent on the heat output you need. Usually, the larger the room, the more heat you need to warm it, so the bigger the radiator will be.
Radiator heat output is measured in BTU, which stands for British Thermal Unit. Room dimensions, insulation quality, windows, and the room’s purpose may affect how much BTU you need.
A simple BTU calculation formula is:
BTU = Room Volume (cubic feet) × Heat Factor
To do this:
- Measure the height, width, and length of the room in feet.
- Times those numbers together to get the room’s volume / cubic feet value. For example, if a room measured 15ft x 12ft x 8ft, you would calculate 15 x 12 x 8 = 1440. 1440 is your cubic feet value.
- Times your cubic feet value with the most fitting heat factor below:
- Well-insulated bedrooms and living rooms: 5
- Bathrooms: 6-7
- Poorly insulated rooms: 8-9
- Adjust the calculation for rooms with large multiple windows by adding 10% or 15-20% for rooms with north-facing windows and rooms prone to heat loss.
The benefit of calculating BTU is that you can efficiently heat your room without wasting energy by overheating it. However, if you’re choosing between radiators with a higher or lower BTU than required, always pick the radiator with more BTU. This ensures your rooms will be sufficiently heated on even the coldest days.
Once you have your BTU value, you can filter online shopping sites to show radiators with that BTU output. If the radiators that show are too large for your available wall space, you might want to consider vertical radiators or installing multiple radiators within one room.
What is a central heating radiator?
A central heating radiator is connected directly to your home's central heating system and uses hot water to heat up. This radiator type is commonly used to heat entire properties.
What is central heating and how does it work?
Central heating radiators work by circulating hot water, heated by a boiler, through pipes inside the radiator. The hot water warms up the radiator, which then heats the air in the room. You can think of central heating radiators as metal hot water bottles. Some types, like convector radiators, have convection fins that increase their surface area, providing more space for the radiator’s heat to transfer to the air around it, enabling faster and more efficient heating.
What is an electric radiator?
An electric radiator uses mains electricity to heat its convectors. This makes it ideal for rooms without plumbing or when you want to heat a room separately (which helps save on energy bills). They should only be installed by a qualified electrician. A good option is ThermoSphere electric radiators, which come in stylish coloured glass panel options. They can be installed anywhere in the home and have various energy-saving features, including open-window detection, programmable heating schedules, and smart-learning technology.
How do electric radiators work?
Electric radiators contain an electric element. The element heats the metal panels, which transfer heat to the air and surrounding room.
Oil Filled Radiators
An oil-filled radiator can be plugged into a mains socket. They contain oil as a heating fluid (not as a fuel) which makes them stay hotter for longer. These radiators are often used as backup or supplementary heaters.
What is a dual-fuel radiator?
A dual-fuel radiator offers both flexibility and control, as it can be heated using both the central heating system and electricity. This is particularly useful in bathrooms, where you may want additional heat without running the entire central heating system. Because of this, many bathroom radiators are dual fuel.
How does a dual-fuel radiator work?
A dual-fuel radiator works similarly to both plumbed and electric radiators. The fluid inside is heated by either the central heating system or an electric element, and this heated fluid warms up the radiator's surface, which then heats the surrounding air.
Types of convector radiators
The most common radiator installed in domestic properties is the convector radiator Type 11, type 21, and type 22 are the most popular.
What is a type 11 radiator?
A Type 11 radiator (single panel radiator) comprises one metal front panel with one row of convection fins on the back.
They are ideal for small rooms or hallways due to their slim profile. Type 11 radiators are less popular as they have a lower heat output than other convector radiator types. This makes them less effective at heating medium to large-sized rooms.
What is a type 21 radiator?
A type 21 radiator (double panel plus radiator) has a front and back metal panel with a single row of convection fins between them.
Type 21 radiators are best for medium-sized rooms, emitting more heat than type 11s. They are often installed in bedrooms.
What is a type 22 radiator?
A type 22 radiator (double panel) is made up of two metal panels with two rows of convection fins between them.
This radiator type is well suited to larger rooms like living rooms and kitchens as they have a higher heat output than type 21. Due to their heating efficiency, type 22 radiators are the most popular type.
What is a type 33 radiator?
Type 33 radiators (triple panel radiators) have three metal panels with three rows of convection fins between them.
These convector radiators have the highest heat output, making them ideal for large rooms. As they have a thicker profile, they are unsuitable for narrow hallways.
It’s also worth noting type 33 radiators are more expensive than other convector types and less widely available.
Type 10 and type 20 radiators
There are also type 10 radiators which have a single metal panel without a convector, and type 20 radiators which contain two metal panels with no convector between them. Type 10 radiators have an extremely compact design, making them great for small rooms and hallways.
Best bathroom radiators
Towel radiators are the most popular type of bathroom radiator. This is because they heat bathrooms and dry damp towels that hang from the radiator’s heated bars. Towel rail radiators work best in smaller bathrooms, and come in both plumbed and electric models.
If you opt for a towel radiator, remember that if you store too many towels on it the air circulation will be blocked, reducing its heat output.
When purchasing a radiator for your bathroom, it’s best to go for a corrosion-resistant finish, such as stainless steel.
Another popular choice for heating bathrooms is the vertical designer radiator. These create a focal point in the room and add a touch of luxury. A trendy option is the anthracite radiator. The dark grey colour has grown in popularity since 2015 as it modernises bathrooms with its contemporary aesthetic.
Designer radiators
Aside from the classic glossy white radiators that we’re used to, there is a wide range of styles available within the designer radiator market. The benefit of these radiators is they provide both functionality and aesthetic appeal. Some widely available options are:
- Vertical radiators: These are both visually attractive and great for areas with little horizontal wall space. The tall radiators come in various sizes and are convenient for kitchen installations.
- A cast iron radiator can be decorated with many elaborate designs, providing an older and more traditional finish.
- Some trendy designer radiators are crafted to look like modern art and can provide a beautiful focal point in a contemporary-style room. However, these modern radiators have a much higher price point.
- Column radiators offer a classic look and are versatile to match various room styles.
Material choice
It may not directly influence your purchasing decisions, but it’s handy to know that radiators are made from different materials. The metals they are made from contribute to their weight, heating efficiency and overall aesthetic. Below are the most common radiator materials:
- Steel radiators are affordable and available in many styles. They take longer to cool down than aluminium radiators and have a modern look. Panel radiators are often made of mild steel, whilst bathroom radiators come in stainless steel, making them rust and corrosion-resistant.
- Cast Iron radiators have great heat retention. So, they keep rooms warmer for longer after the heating has been turned off. This metal gives a traditional vintage look, making them perfect for period-style homes. As cast iron is heavy, strong wall fixings are required to mount this radiator. Because they are more difficult to handle, plumbers may charge more to install them.
- Aluminium radiators are lightweight, modern, and energy-efficient. This metal heats up and cools down quickly, so aluminium radiators don’t retain heat for long. Aluminium is usually for designer radiators, due to the metal's flexibility.
See below a summary of the different radiator materials. This table also includes copper, brass, and glass options.
Picking an energy-efficient radiator
If you’d like to reduce your heating costs or be more eco-friendly, look for energy-saving features. These include:
- Radiators that are compatible with thermostatic radiator valves. This type of valve lets you control the temperature of individual rooms, preventing lesser-used rooms from overheating and wasting energy.
- Radiators with quick heat-up times. Models that heat more quickly spend less energy on the initial warm-up phase, and heat rooms more efficiently. Aluminium and copper radiators are ideal choices.
- Electric radiators with smart technology. Some electric radiators let you set a heating schedule, have an eco mode to optimise energy consumption, open-window detection, and more useful features to prevent energy waste.
- Radiators requiring less water to operate heat up quicker and use less energy to maintain their temperature. They also reduce the load on your boiler. Also, consider the positioning of the radiator within the room. Placing radiators beneath windows helps to counteract cold air and improve heat circulation. However, in a large room, it may be beneficial to install multiple smaller radiators around the room for more targeted heating. (For example, installing a radiator near your living room sofa.)
Compatibility
Before you purchase a shiny new radiator, it’s crucial to check if it’s compatible with your home’s heating system. Otherwise, you could face costly installation fees if you adapt your current one.
System compatibility
- If your house has a wet central heating system where the radiators are connected to a boiler, see if the radiator you are purchasing is compatible. This is especially important for replacement radiators. (See if you have a closed or open-vented system. Some radiators are not suitable for high-pressure environments.)
- If you’re buying an electric radiator, make sure your home’s electrical system supports the radiator’s wattage. You may need to consult a qualified electrician to find out.
- If you’d like a dual-fuel radiator, you’ll need to check if the radiator will be compatible with both your central heating system and electrics.
Size compatibility
Aside from system compatibility, you’ll need to see if the radiator you’d like to purchase will fit in your home. Measure the available space you have (radiators are usually mounted onto the wall below the window sill) and compare it to the radiator you wish to buy. For rooms with limited wall space, vertical radiators can provide a solution.
Standard UK radiator sizes
Radiator sizes are measured in both height and width, and the standard sizes in the UK are:
- Height: 300mm, 400mm, 500mm, 600mm, 700mm, and 800mm.
- Width: From as narrow as 400mm to as wide as 2000mm or more.
Pipe connections
Measure the distance between the pipe connections to your old radiator, making sure the new radiator’s connections match up. If the pipes do not align, the pipework will need adjusting.
There are also bottom and side entry connections to consider. Most modern radiators have pipes that enter the bottom of the radiator, whilst some older radiators have side-entry connections. Adaptors or pipework adjustments are needed to accommodate differences in pipe entry location.
Wall mounting capability
If your new radiator is made of a heavy material, such as steel or cast iron, it’s best to check if your wall is strong enough to support the radiator’s weight. In particular, drywalls often require additional support.
If the radiator you are installing is too heavy for the wall, see if it can be floor-mounted via feet.
Cost considerations
One of the main factors to consider when purchasing a new radiator is the cost. Below is a table showing which radiators you can buy within each budget range.
*The prices shown are calculated using Builder Depot’s radiator range and were last updated in October 2024.
If you have a low budget, you can always paint white radiators to make them more stylish. Radiator paints and metal paints (like the Dulux Heritage eggshell range) are perfect for customising your radiators.
To learn more about customising your radiator, such as how to make your pipework look neater, read our radiator accessories guide.
Radiator maintenance
To save money, it might be worth fixing your existing radiator rather than buying a new one. Here are some common radiator problems and how they can be fixed:
- The radiator doesn’t heat evenly: This can be caused by trapped air and sludge. Try bleeding the radiator and flushing the system.
- Leaks: If the radiator is leaking, it could be caused by corrosion or damaged pipes and valves. Identify the source of the leak and replace any damaged parts. If there is a small leak within the radiator itself, you can temporarily use a radiator sealant.
- The radiator doesn’t heat up: If the radiator isn’t getting hot, it could be because of a closed valve, trapped air, or issues with your central heating system. Check the radiator valves are open, bleed the radiator, and check if your central heating system is operating correctly.
- The radiator makes noises: Radiators make noise if they contain trapped air or if the pressure in your central heating system is too high. Bleed the radiator to remove the trapped air and adjust the pressure on your boiler to the recommended level.
- Corroded rusty surface: Humidity may cause your radiator to become rusty. If there is only minor corrosion and no leaks, you can sand and repaint the radiator.
Summary
When purchasing a new radiator, the main factors you should consider are BTU (heat output), radiator type/style, available space for installation, and your budget. To learn more about heating, check out our handy Underfloor Heating Guide.