PHAM NEWS | SEPTEMBER 2026 26 Radiators& Towel Warmers


Why you should care about compliance


With some radiators carrying infl ated heat output claims, Chris Hone of Myson explains the risks for installers and why accurate calculations matter.


R


adiator suppliers have an important obligation under the Construction Products Regulation


2011. It stipulates that, under the designated standard BS EN 442, detailed independent testing must be carried out to measure the rated thermal performance output of the radiator at Delta T50 and Delta T30 in watts. These calculations are critical


when it comes to specifi cation decisions, enabling installers to source the right products for the right applications, in turn ensuring satisfi ed customers whose heating systems perform effi ciently. However, the Manufacturers’


Association of Radiators and Convectors (MARC), of which Myson is a member, in collaboration with the Offi ce for Product Safety and Standards (OPSS), has warned that some radiators in the UK market are being advertised with exaggerated heating claims. The impact of this is signifi cant, potentially leaving households cold and out of pocket, and heating installers with a poor reputation.


Crunching the numbers Under BS EN 442 and the Construction Products Regulation 2011, radiator outputs must be independently tested and declared using standardised conditions, including Delta T50 and Delta T30, and supplied with a Declaration of Performance (DoP) showing verifi ed heat output values. At Myson, this is standard procedure. But as MARC highlights,


some suppliers are promoting outputs using non-standard conditions, such as Delta T60, which can infl ate perceived performance and distort product comparisons. A radiator might produce


1,000W when operating at Delta T60 (for example, 85/75°C), but the same radiator at Delta T50 (say 75/65°C) may deliver around 800W. This means a system designed around a 1,000W heat demand could be underperforming if the output


Chris Hone GB sales director for Myson


was based on the higher Delta T rating. In practice, this means:


• Higher energy bills for


customers who have to turn up boilers or heat pumps to stay warm.


• Colder homes, as radiators


can’t provide the heat needed to warm rooms.


• Increased carbon


emissions. • Inadvertent non-


compliance for installers.


• Disgruntled customers. • Additional costs for


installers who may be required to remedy the underperforming work. The issue will become


With low-


temperature heating becoming increasingly


important, having reliable performance data is essential when selecting the right emitter


more signifi cant as heating systems continue to evolve. For example, the government is aiming for 450,000 heat pump installations a year. Heat pumps typically operate at lower fl ow temperatures than traditional boilers, meaning it’s vital that radiators are correctly sized to deliver the required output under those conditions. If a radiator’s performance


has been overstated, the system may appear underpowered once installed, even if the heat pump and system design have been specifi ed correctly. This creates unnecessary troubleshooting for installers and risks


The double TOPAZ bathroom radiator from Myson features generous tubular water channels to deliver more heat


misdirecting attention towards the heat source – which could potentially create further consumer uncertainty around the technology.


Compliant calculations The issue of non-compliant heat output claims is a growing focus across the sector, and MARC and OPSS are working to raise awareness of this issue among consumers, installers and suppliers. Andy Phillips, chair of MARC, has emphasised: “Using Delta T60 values or higher is in breach of the Construction Products Regulation and also undermines the integrity of our industry.” Suppliers found to be exaggerating their radiator outputs risk investigation by OPSS and other regulatory bodies, the consequences of which can be signifi cant. For installers, there are key


steps that can be taken to ensure compliance.


• Choose a trusted supplier


that focuses on transparency and support, which will help you specify with confi dence and deliver systems that perform as intended. Myson provides independently verifi ed performance data, clear technical documentation and products tested to recognised industry standards.


• Check the Declaration of


Performance (DoP) before purchasing a radiator from a supplier. This is the legal document that sets out the Delta T values and other important information for the radiator. It should be available directly from the supplier or via their website.


declared at Delta T50 and Delta T30, and in Watts.


• Confi rm that heat


output fi gures are supported by independent testing in accordance with BS EN 442. • Avoid comparing products


using diff erent Delta T values, as this can create misleading performance comparisons.


• Use only compliant heat


output fi gures when carrying out heat loss calculations and system design. These steps ensure the


products you use are compliant and fi t for purpose, building a happy customer base and helping to avoid costly corrections.


Specify with confi dence For installers, confi dence in a radiator specifi cation starts with confi dence in the information behind it. Myson provides independently verifi ed heat output data, clear technical documentation and a comprehensive range of radiators and heating solutions designed to support accurate specifi cation across applications. ◼ phamnews.co.uk/926/57


• Check that heat outputs are


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