Imagine buying a car advertised as reaching 30 miles per gallon, only to discover it barely manages 10. Now, imagine that happening not just with your car, but with your radiators, and that the “overstated mileage” translates to higher heating bills and missed climate goals. This shocking reality is playing out right now across the UK.
Misleading Metrics
Many consumers assume UK regulations safeguard against false advertising. Unfortunately, when it comes to radiator heat output, that’s not the case. Millions of radiators are sold annually with inflated heat claims, often exceeding 25% of the actual output. This discrepancy isn’t a minor quibble; it impacts heating efficiency, leading to higher bills and missed Net Zero targets.
The Investigation Begins
To uncover the truth, we purchased five radiators from five different UK websites, each acclaimed for their high heat outputs. The objective was simple: test these radiators at a regulated lab and compare their actual heat outputs to those advertised.
We drove the rads to BSRIA (Building Services Research and Information Association), a leading authority in testing, who conducted the evaluations. Their testing environment – a specialised, unventilated booth with water-cooled surfaces – ensures accuracy, free from external environmental influences. Radiators were measured and tested over an 8-hour period, with continuous data collection.
Spoiler Alert
The results, when they arrived, were as bad as we had anticipated, and in some cases, even worse, leaving us unsurprised yet deeply concerned:
- Radiator 1: Advertised output: 953 Watts (3250 BTUs); Actual output: 760 Watts (2592 BTUs); Overstated by 25%
- Radiator 2: Advertised output: 1026 Watts (3500 BTUs); Actual output: 786 Watts (2680 BTUs); Overstated by 31%
- Radiator 3: Advertised output: 927 Watts (3160 BTUs); Actual output: 738 Watts (2517 BTUs); Overstated by 26%
- Radiator 4: Advertised output: 988 Watts (3371 BTUs); Actual output: 716 Watts (2442 BTUs); Overstated by a whopping 38%
- Radiator 5: Advertised output: 889 Watts (3034 BTUs); Actual output: 712 Watts (2428 BTUs); Overstated by 25%
A Widespread Issue Beyond Sample Size
The results from these five radiators are a small representation of a much larger issue plaguing the UK radiator market. With millions of units potentially sold with exaggerated heat outputs, the economic and environmental impact is profound. Consumers face higher bills, and the nation’s Net Zero targets become harder to achieve due to increased energy wastage.
These findings also raise critical questions about regulatory enforcement and consumer protection. The overstated outputs not only lead to financial losses for consumers but also betray the trust placed in regulatory compliances and standards.
The Need for Urgent Action
Our investigation underscores a pressing necessity for government and regulatory intervention. It’s imperative that regulations are not just present, but vigorously upheld to safeguard consumer interests and maintain the integrity of the market. This issue transcends mere deceptive sales practices; it touches upon the wider ramifications for energy efficiency and the stewardship of our environment.
The radiator heat output scandal in the UK is a wake-up call for consumers, businesses and regulators alike. It underscores the importance of rigorous testing and transparent marketing. As consumers, it’s vital to stay informed and demand accountability. Sharing this article, supporting the petition below and calling for regulatory action are steps we can take to bring about change. Together, we can confront this issue, protect consumer interests and contribute to a more sustainable future.
We would like to call upon the readers and members of Renewable Heating Hub to actively spread the word about this vital concern. Please share this article and support our petition for regulatory reform at UK Radiators.com. Your voice can make a difference in bringing an end to this deceitful practice and paving the way for a more honest and efficient market.
Disgraceful situation, especially when using heat pumps as they runt at a lower temperature, has this been sent to the ASA , Trading Standards or Government? well done for doing the testing.
Unfortunately we have a situation at present where the various bodies are pointing fingers at each other as to who is responsible. Our petition aims to address this by going to the DBT and DESNZ directly, as they have the authority to determine who needs to take action. If you could sign it would be very much appreciated 🙏
Just wanted to highlight that there is a petition you can sign at UK Radiators.com
Sorry, but where exactly is it possible to sign the petition? URL please. I can’t find it; certainly not at the link you already gave – that seems to just link to a PDF.
@Dave, this link takes you a page with the petition at the bottom: UK Radiators.com
Hi Dave, the petition form is just above where the letter is but it does take a second to load.
Both flow rates and temperatures affect output, and I doubt BSRIA has the technology to match them to design specifications.
Manufactures have failings but distorting the truth is not one of them.
their failings are that they don’t explain themselves, the “intellectual capital” around radiators performance is not explained. And people jump to the wrong conclusions.
Hi Alec, thanks for your comment, I appreciate your perspective on this and you are correct that flow temperature affects output. This is why radiators are delta rated, so that it’s clear that the radiator outputs different amounts at different temperatures.
BSEN442 – the regulation that governs the manufacturer and sale of radiators, dictates that radiators must be tested by a notified body (BSRIA is the only one in the UK) and advertised using the rated thermal outputs at both Delta 50 and Delta 30.
The problem with these radiators is that they are being advertised with heat outputs that far exceed the rated thermal outputs achieved during testing. So in these cases (and many others), yes the manufacturers are distorting the truth.
If you have not done so, please watch the 7 minute documentary we produced (available on our website on the link above) as the evidence speaks for itself.
Happy to chat further or answer any questions you may have.
Thanks again
Rob
Actually they do. My case is a prime example.
Catalogue provided by my installers dated 2022 (January 2023 according to Adobe Metadata) output, vs same manufacturer catalogue dated late 2023 and latest 2025 are rated -28% less. So the fact that my installers used the 2022 brochure, is a factor to why my radiators are undersized, and each of my floors have around 33% shortfall.
Do you still think manufacturers are not inflating figures?
@Rob Nezard is the biggest expert I can think of in rads… what do you think Rob?
@Mars thanks Mars. Yeah it is a real issue.
We are working to drive change through the market but it’s a slow process.
We are actually pulling together case studies at the moment, @DREI would you be open to working with us on this?
@Rob Nezard you can see more of Drei’s rad dramas here as part of his overall bodge:
And I’m sure @DREI will be up for it… Drei let me know if you’d like me to connect you to Rob via email.
Hi @Rob,
I’d be more than happy to contribute. I have the original emails from my installer with the 2022 catalogue attached, as well as the later 2023 catalogue and the current 2025 version from Kartell’s website. Heat Geek actually recommended using UKRadiators.com instead of others precisely because of their MARC membership, which makes this all the more relevant.
I’ve also tracked down the 2021 (not 2022) and 2023 brochures online:
2021 – Kartell Catalogue, p.4 (MJ Bathrooms)2023 – Kartell Designer Radiators, p.4For reference, my radiators are K-Rail Aspen models.
Taking one of my installed models as example:
Double Column ASP60-115DW 600 x 1140
2021 output: 8,6452023 output: 6,223→ A 39% reduction.
That is a staggering discrepancy. In fairness, I can almost forgive my installers for the shortfall in design, because they used what they were given at the time. Then again, maybe they should have checked against the 2023 brochure, even so, Kartell’s shifting figures are the main root of my problem, with the poor buffer use and configuration second.
In my case there was no need of a buffer, or just a small up to 10l volumiser, because the pipe going from the heat pump to the property is about 18 meters, and they did not take that in consideration part of the Samsung’s 50l water volume requirement.
In my view, installers like mine should be pursuing a claim against Kartell, especially if I’m not the only customer facing radiator shortfalls caused by these catalogue inconsistencies.