4 Dehumidifiers Falling Short of 10% of Claimed Dehumidifying Capacity – Worst Discrepancy Reaching as High as 35%

14 February 2018
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4 Dehumidifiers Falling Short of 10% of Claimed Dehumidifying Capacity  – Worst Discrepancy Reaching as High as 35%

As the humid weather sets in, many homes are getting their dehumidifiers ready to stay dry. The Consumer Council has put 14 models to its latest dehumidifier test, and found 4 of the models to be over 10% short of their claims in dehumidifying capacity based on the manufacturers’ test environment; one model was even as much as 34.8% short. The test findings have been referred to Hong Kong Customs and Excise Department for follow-up actions. Furthermore, the only one desiccant-type sample though stable in dehumidifying performance under various environments, its energy factor is the lowest of all 14 samples.
The test results once again revealed, the test environment favoured by dehumidifier manufacturers in dehumidifying capacity measurement does not accurately reflect actual usage conditions. However, merchants still choose to promote the products based on the dehumidifying capacity measured under the manufacturers’ own test environment, which could be misleading to the consumers. The Council has repeatedly called on the manufacturers to discontinue the use of their own test environment, but to this date there has not been any clear improvement, the situation is most worrying. 
Included in the test were samples of 13 compressor-type (including 1 inverter-type) and 1 desiccant-type priced from $1,799 to $5,990, and conducted with reference to the US National Standards  ANSI/AHAM DH-1-2008, the Electrical and Mechanical Services Department’s Mandatory Energy Efficiency Labelling Scheme (EMSD’s MEELS), and IEC 60335-2-40 on test items covering: dehumidifying performance, the measured daily dehumidifying capacity vis-a-vis their own claims, quietness, maximum operating conditions, low temperature, safety and ease of use.
The samples were put through 3 different test environments in the measurement of their daily dehumidifying capacity and energy factor: the standard environment (26.7oC, 60%RH), the manufacturers’ own environment (30oC, 80% RH), and the low temperature environment (20oC, 60%RH). Owing to variations in design with different dehumidifying capacity, performance evaluation of the samples is based on the measured dehumidifying capacity matching against their own product claims.
Annual electricity costs $94 - $218; desiccant model lagging behind 
On the basis of 450 hours of usage a year at $1.2 per electric unit, the annual electricity cost of the 14 samples under the standard test environment was estimated to cost from $94 to $218. But consumers should compare products for their energy factor under the standard test environment, and for the same dehumidifying capacity these with, the higher the energy factor, the more energy-saving they are.
The results showed, under the standard test environment, the measured daily dehumidifying capacity of the compressor-type ranged from 6.28L to 20.58L; in 11 samples the measured capacity was higher than the rated value by 0.6% to 4%, while 2 samples were in contrary lower than the rated value by 1.4% and 4.3%, but the discrepancy was within the 10% acceptable tolerance set for the Mandatory Energy Efficiency Labelling Scheme (MEELS). 
Under the manufacturers’ own test environment, the measured dehumidifying capacity of the compressor-type was clearly higher than it was under the standard environment, ranging from 10.1L to 33.59L. Nonetheless, the measured capacity of 3 models still fell short of over 10% of their claimed values, by 16%, 19.2% and 27.4% respectively. Under 32oC and 80%RH test environment, 2 models’ measured capacity was less than their own claims by 13.7% and 34.8%. Under the low temperature test environment, the measured capacity of the compressor-type samples was lower than it was under the standard environment by an average of some 30%, with only 4.61L to 15.21L.
The sole desiccant-type dehumidifier among the samples, though stable in performance under all 3 test environments, its dehumidifying capacity was measured to be only 4.67L to 4.93L, its dehumidifying performance clearly lagging behind the other models.
11 models with energy efficiency Grade 1 rating
On energy factor, the test was based on the samples’ measured dehumidifying capacity and power consumption to calculate the dehumidifying capacity a dehumidifier could extract per unit of electricity, the higher the value the better its energy efficiency. The results showed, for compressor-type dehumidifiers, 1.51L to 2.94L per unit under the standard environment rising to 2.05L to 4.22L per unit under the manufacturers’ own environment (in which the temperature and RH are higher), and lowering to 1.24L to 2.4L per unit under the low temperature environment. The desiccant sample fared rather poorly with 0.53L to merely 0.56L per electricity unit under the three different types of environment.  
Accordingly, 11 models of the compressor-type dehumidifiers would acquire Grade 1 rating on the energy label, and 2 others Grade 2. One model with Grade 1 rating on the energy label, however, should be classified as Grade 2 only. Nevertheless, the difference in energy factor was within the tolerable level (10%) and did not violate the requirements of MEELS. The Council has referred the test findings to the EMSD for any follow-up action deemed necessary.
Further, 13 samples passed all the safety test items; only 1 model was detected with a safety concern. This could occur when the water tank of the sample was removed, a finger can find its way through the gap with force to touch the insulated internal wire.  Improvement is needed for protection against access to live part.  
In the choice and use of dehumidifiers, consumers are reminded to take heed of the following:
  • Consider your living surroundings and personal needs in choosing one with suitable dehumidifying capacity;
  • It is not advisable to use the set of values based on the non-standard manufacturers’ own test environment for product comparison; consult the MEELS energy label for energy factor, dehumidifying capacity and energy efficiency grading;
  • When drying laundry neither cover the air ventilation grills of the dehumidifier with clothing, nor place laundry still dripping wet on top of the appliance for drying;
  • Make good use of the timer to avoid prolonged use or forgetting to switch off the appliance. Avoid also leaving a dehumidifier on without supervision or when sleeping at night;
  • Clean regularly the water tank and dust filter, prevent bacterial growth and dust accumulation that may obstruct the normal operation of the dehumidifier.

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