Note: This advice is given by the CAP Executive about non-broadcast advertising. It does not constitute legal advice. It does not bind CAP, CAP advisory panels or the Advertising Standards Authority.


Plug-in heaters are electrical devices that warm the air around them. Marketers wishing to make objective claims about such products must ensure that they hold robust evidence for these claims – but they should also be aware that suggesting the product is an alternative to central heating or other heating methods is very likely to breach the Code.

Economical/’cheaper than’ claims

Many of the claims CAP has considered historically are claims that mini heaters are a viable and cheaper alternative to central heating.CAP understands from the Energy Saving Trust that at this time, gas is cheaper than electricity. For a whole house, gas central heating radiators can heat rooms effectively by creating natural convection currents. For heating a single room, it would also likely be cheaper and more efficient to run a single radiator. For homes with electric heating, typically electric storage heaters that could use the Economy7 tariff during off-peak hours would be cheaper than the standard electricity tariff the advertiser’s product would run off.

In light of this, it is very likely the ASA would consider ads for electric plug-in mini-heaters which claim – directly or indirectly - that such products are an economical alternative to central heating, to be materially misleading.

In January 2023, the ASA investigated a paid-for online display ad which stated "Use This To Stay Warm & Save Money This Winter. If you hate the cold but don’t want to raise your heating bills, you need to get this”. Once clicked, the landing page included the claims “Analysts are warning us this winter will be “extremely expensive, tough and long for many Brits” and “It'll warm up your rooms quickly, efficiently, and most importantly - cheaply! ... If you hate being cold, but don't want massive central heating bills - this is the best solution we can see right now.” The ASA considered that consumers would interpret the ads to be stating that, in the context of a cost-of-living crisis, the product was an alternative to gas central heating and other heating systems because it heated rooms more economically. The ASA sought advice from the Energy Saving Trust when reaching their decision, and ultimately concluded that there was no evidence that the product could provide an economical form of heating, either in one room or throughout a property, and therefore it was unlikely that a small heater would be a viable source of sufficient heating for most households (Ecom 7 Ltd t/a Instacool, Heater Pro X, 25 January 2023).

The same year, the ASA investigated a similar ad for a heater which stated “Brits Are Using New Heating Device to Combat Soaring Energy Bills” and “…This is not only good for the environment, but also good for your wallet... In addition, the Keilini Portable Heater is really cheap, tiny and very handy … With winter just around the corner, the Keilini Portable Heater is the cheapest yet most convenient way to stay warm and cozy”. Again, the advertiser provided no evidence that the product could supply the equivalent heating capabilities of other heating systems (with in a single room or whole house) at a cheaper price, nor did they provide evidence that the heater was an economical way of heating a room or property. The complaint was therefore upheld (Keilini Technology International Co Ltd, 25 January 2023). 

In 2020, the ASA also ruled against a claim that a heater could save “over 50% on heating” when compared to other heaters. Whilst the advertiser provided a speadsheet comparing against four different gas heaters, the ASA considered the claim was an absolute one and comparing against only four other products was insufficient. Furthermore, the data provided for these four heaters was also inadequate (John Mills Ltd t/a JML, 1 April 2020).

Efficiency claims

Marketers should also not claim nor imply that electric plug-in heaters are an efficient alternative to central heating or other heating methods - for instance, by stating or implying that the product provides comparable heating performance to central heating – unless they hold very robust evidence.

The ASA investigated a further ad for the Instaheat mini heater which stated, among other claims, “A convection ceramic heater with an incredible 99.8% efficiency” and “Wait while this powerful device heats the entire room, car, RV, garage, etc ... Up to 500 square feet”. However, the advertiser did not provide any evidence to substantiate their claims, and therefore the ASA concluded the ad breached the Code (Label Products BV t/a InstaHeat, 25 January 2023).

Similarly, in 2020, the ASA investigated the claim “In an outdoor breeze, the Instant Heater can pump out an extra 10 degrees more heat than gas can”. The ASA expected to see evidence that the advertiser had tested their heaters against a range of gas heaters in an outdoor environment – however, they found the advertiser had only tested against one other heater inside a room, using a fan to simulate wind. Overall, the ASA considered that the evidence received was insufficient to support the claim made (John Mills Ltd t/a JML, 1 April 2020).

General comparisons

It’s important to note that the CAP Code does not specifically rule out comparisons between plug-in heaters and central heating or other methods – however, the comparison should be fair and make clear the limitations of the heater vs. the alternative heating source. As above, claiming that the product is an ‘alternative’ or even a “substitute” to another heating source suggests that the efficacy is on par with that heating source, and is, in the absence of any evidence to this effect, likely to breach the Code.

Claims such as “No other heater is this efficient( Label Products BV t/a InstaHeat, 25 January 2023) are likely to be seen as objective comparisons against identifiable competitors. Therefore, marketers will need to follow our guidance in Comparisons: General, Comparisons: Identifiable Competitors and Comparisons: Verifiability.

Other objective claims

Advertisers must hold adequate evidence to support claims that consumers are likely to regard as objective and that are capable of objective substantiation, such as “tested and approved for home safety by the top regarded institutions” (Label Products BV t/a InstaHeat, 25 January 2023). Marketers should also not exaggerate the capabilities of their product. See Misleading advertising for more.

Marketers are also reminded that any environmental claims about plug-in heaters must adhere to Section 11 and our environmental guidance at www.asa.org.uk/environment.

See also Environmental claims: Electricity from renewable sources - domestic energy production and Types of Claim: No 1 


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