Are your radiators really heating your home? Why choosing the right radiator matters for your comfort, bills and the planet

The Manufacturers’ Association of Radiators and Convectors (MARC) is urging consumers to check the specification around heat output when buying radiators, as some retailers are using non-standard figures so their radiators appear to provide more heat output than they really do.  MARC and its members have been working tirelessly to raise awareness of this issue and bring about change.

 What’s the problem?

Businesses must legally declare the heating output of radiators using a measurement called Delta T 50 (ΔT50) for standard heating systems and Delta T 30 (ΔT30) for low temperature systems.  Delta T reflects the difference between the water temperature in your heating system and the target ambient room temperature in your home.  The law also requires that all radiators are supplied with a Declaration of Performance (DoP).  The DoP is to show that the radiators have been tested by an independent laboratory and that the heat outputs being declared are accurate.  This ensures you get what you pay for and your installer can accurately size your radiators and your heating system.

 However, some businesses are declaring the heat output of radiators at Delta T 60 (ΔT60) or higher.  This exaggerates the radiator’s heat output and means your home could feel colder and your energy bills could rise.

 Why it matters to your wallet and comfort

What this means is that you could be buying the wrong size radiator for your room.  Incorrectly undersized radiators mean:

• Higher energy bills because you turn up your boiler or heat pump to stay warm.
• Colder homes, as radiators cannot deliver the heat that is needed to properly warm the room.
• Heat pumps may appear to underperform, when the real issue is radiators that are not the correct size for the room and the type of heating system.
• Increased carbon emissions, making it harder for the UK to hit net zero targets.

 Andy Phillips, Chair of MARC, explains: “Consumers deserve radiators that do the job they are promised.  Advertising radiators using mis-stated figures is misleading and can leave people cold while paying higher bills.  We urge consumers to check the product specification before purchasing.  The heat output should be stated at Delta T 50 and Delta T 30.  This means that you and your installer will be able to ensure that the right size of radiator is purchased for your particular property.  All radiators purchased should be supplied with a Declaration of Performance.” 

 Regulators are watching

The Office for Product Safety and Standards (OPSS), who is the National Regulator for construction products and enforces the Construction Product Regulations, has backed MARC’s efforts.  Duncan Johnson, Deputy Director of Construction Products Regulation for OPSS, said: “We are delighted to be working with MARC to address the challenges being faced in the radiator industry, helping to ensure that manufacturers and suppliers are providing information that is both accurate and compliant with the standard.”

 Businesses declaring radiators using Delta T 60 and not meeting the legal requirements are at risk of being investigated by OPSS and other regulators.

 What should consumers do?

• Check that businesses declare the output of radiators at Delta T 50 (ΔT50) and Delta T 30(ΔT30) only and not any other Delta T values.
• Speak to your installer and confirm they are using Delta T 50 or Delta 30 figures for heat loss calculations when specifying radiators for your home. 
• Avoid comparing Delta T values other than Delta T 30 and Delta T 50, as higher values falsely promise higher heat output.
• Check the Declaration of Performance before making your purchase.  This is the legal document that sets out the Delta T values and other important information for the radiator.  You can request the Declaration of Performance from the business supplying the radiator.  It may also be available on the business’s website.

 Buying the correctly sized radiator ensures your home is warm, your bills are fair and you are helping the UK’s transition towards net zero.

 For more information on how to choose compliant, efficient radiators, visit Legal Requirements For Radiators — MARC - Manufacturers Association of Radiators and Convectors