A cheap Xiaomi can be just as good as an expensive Dyson when it comes to hair dryers, the Consumer Council said on Thursday, as it warned that some manufacturers claims are nothing but hot air and some models are a bit of a damp squib.

“The primary function of a hair dryer is to dry hair, thus drying rate is a critical factor,” the watchdog noted as it presented the findings of a study involving 13 hair dryer models on sale in Hong Kong, ranging in price from not much more than HK$100, to well over HK$3,000.

Instead of actual hair, a cloth moistened with water was used to test how good the different dryers were, with the council blasting the fabric for a minute at a temperature of around 75°C and then comparing the weight before and afterwards to see how much water had evaporated.

“Results showed that the drying rates of the 13 models ranged from an average of 3.4g to 6.3g per minute,” the watchdog said, adding that it was then able to deduce that the fastest model could dry hair in five minutes, while the slowest would take more than nine.

It noted that people could be tempted to speed up the process by whacking up the temperature, but warned against getting too carried away.

One model was found to generate air temperatures of up to 108 degrees Celsius – which the council pointed out is higher than the boiling point of water – posing a risk of damaging hair cuticles.

The body’s chief executive, Gilly Wong, said the ideal temperature for drying hair is less than half that.

“One study from Korea back in 2011 said that the best distance [away] is about 15cm and the temperature should be around 47 degrees Celsius. So that it will dry your hair but it will not damage your hair that much," she said.

The council also noted that different hair dryers come with different operating costs and said choosing one with a lower power rating would not save electricity if you had to use it for much longer than a more powerful model, just to get the job done.

“Hair dryers with a lower drying rate would need a longer drying time, which might increase the energy consumption …. If there are more family members in the same household and the hair dryer is used more frequently, the electricity cost would naturally be higher.”

People with frizzy hair were also advised not to believe everything manufacturers say about how their dryers can help them thanks to the negative ions they generate.

One model boasted the ability to produce 100 million negative ions, but in reality it could only muster about 16 million.