Ten out of 18 dehumidifiers are slower at absorbing moisture than they claim, according to the Consumer Council. Their capacities ranged from three to 23 per cent lower than accompanying literature claimed. The measurement was taken by litres of water absorbed over 24 hours. Two models by Mitsubishi Electric and two others by Whirlpool and Philips costing $2,980 to $3,780 performed the worst. However, China-made Gree's model CF 0.5 D II turned out to be 24 per cent more efficient than it claimed. Council spokesman Dr Lo Chi-kin said manufacturers had based their claims on unrealistic temperature and humidity figures. 'Dehumidifying capacity is higher when tested at conditions of higher temperature and humidity,' Dr Lo explained. 'Such conditions do not reflect a realistic situation.' He also advised people to turn off electrical appliances such as dehumidifiers before going out because overheating could cause fires. Mitsubishi's Hong Kong agent admitted the dehumidifying capacity was lower than that obtained by the council but disputed some of the council's standards. Philips and Whirlpool said their machines had been certified for quality, but modifications might be made, to ensure they met manufacturing claims.