The Dehumidifying Capacity of 40% Dehumidifier Measured under Standard Test Environment was Lower than Its Claim Performance of Models with Air Purifying Function Varies Significantly

17 February 2020
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The Dehumidifying Capacity of 40% Dehumidifier Measured  under Standard Test Environment was Lower than Its Claim Performance of Models with Air Purifying Function Varies Significantly

Owing to the city’s humid climate, many households have a dehumidifier that is highly durable and shall be chosen with great care. In recent years, 2-in-1 air purifying dehumidifiers highlighting dual-use and space-saving claims emerged in the market. The Consumer Council and Electrical and Mechanical Services Department (EMSD) jointly tested 4 models of 2-in-1 air purifying dehumidifiers and 10 models of conventional dehumidifiers to find that the measured daily dehumidifying capacity of 4 models was lower than its claim, under both the standard test environment and the manufacturers’ own test environment; the measured dehumidifying capacity of 1 model was almost 15% lower than its claim under manufacturers’ own test environment. The test findings have been referred to Hong Kong Customs and Excise Department (C&ED) for follow up. All of the tested models marked with Grade 1 rating on the energy label but in fact 1 of them was only Grade 2 if calculated based on its test result; 2 models with similar dehumidifying capacity varied by over 60% in energy factor under the standard test environment. Consumers are advised to compare the energy factor stated on the energy label carefully when choosing the same dehumidifying capacity of dehumidifiers, the higher its energy factor, the better its energy-saving performance. 

A higher daily dehumidifying capacity will be obtained for dehumidifiers under a higher temperature and relative humidity environment. The Council has repeatedly urged the manufacturers not to claim and advertise the daily dehumidifying capacity measured under the manufacturers’ own test environment because it does not reflect the actual circumstances of use. However, no improvement has been observed. Consumers need to stay alert and not be misled.

Included in the test were 14 models of compressor-type, of which 4 models were 2-in-1 air purifying dehumidifier claiming able to filter particulate matter such as cigarette smoke and dust. The retail price of the 4 models of 2-in-1 air purifying dehumidifier is generally higher, ranging from $4,688 to $5,980; whereas the price difference of conventional dehumidifier varies significantly with 4 models of lower dehumidifying capacity (8.5L to 9.7L) ranging from $1,899 to $2,780 while 6 models of higher dehumidifying capacity (15.2L to 18L) ranging from $3,688 to $5,480, representing a difference of over 45% for both types. The test items included dehumidifying performance, safety and ease of use. The air cleaning performance of 2-in1 air purifying dehumidifier was also tested for the first time.

Dehumidifying Performance

The daily dehumidifying capacity of 14 models measured under the standard test environment (26.7oC, 60% relative humidity, or RH) was from 8.77L to 17.9L, of which 6 models had a lower dehumidifying capacity than its claim, 5 were by 0.1 to 1.1% and 1 was by 6.9%; whereas the daily dehumidifying capacity measured under the manufacturers’ own test environment (30oC, 80% RH) was from 14.75L to 29.4L, of which 8 models had a lower dehumidifying capacity by 1.5% to 14.6% than its claim. The model with the largest discrepancy has exceeded the international acceptable tolerance level (10%). Relevant test results have been passed to the C&ED for follow up.

On energy factor, the test was based on the models’ measured dehumidifying capacity and power consumption to calculate the dehumidifying capacity a dehumidifier could extract per unit of electricity. The test showed that the test models could extract 1.68L to 3.19L per unit under the standard test environment but could extract a higher 2.35L to 3.64L per unit under the manufacturers’ own test environment at higher temperature and humidity. Anyhow, consumers must be aware that the test data under test environment commonly used by the manufacturers does not necessarily reflect the actual conditions.

It was also found in the test that the energy factor measured under the standard test environment varied among models with similar dehumidifying capacity. For instance, 6 models with daily dehumidifying capacity over 15L, the difference between the model with the highest energy factor (3.19L/unit of electricity) and the lowest (1.98L/unit of electricity) varied by 61%. Hence, consumers choosing dehumidifier with same dehumidifying capacity could also compare the product’s energy factor stated on the energy label in order to choose a more energy-saving and environmentally friendly product. The Council also estimated the annual electricity cost of each model based on the usage of 450 hours per year at $1.2 per electricity unit. The annual electricity cost of each models ranged from $96 to $203, of which 6 models with higher dehumidifying capacity (15.2L to 18L) could vary in over 75% difference in electricity cost.

All models claimed to have obtained Grade 1 energy efficiency label. However, 1 model was calculated to be Grade 2 only even though its discrepancy in energy factor did not exceed the international acceptable tolerance level (10%) and the Mandatory Energy Efficiency Labelling Scheme. The energy factor of dehumidifier is classified as essential information for consumers and manufacturers should therefore practically enhance accuracy of the production information.

Over 70% of dehumidifiers currently in the market have obtained Grade 1 energy label. According to the proposed grading requirement listed in the EMSD’s consultation document last year and the Council’s test result, the energy efficiency grading of some models was to be adjusted, 4 models will be rated Grade 1, 8 models rated Grade 2 while rest of the 2 models rated Grade 3. As the proposed grading requirement has yet been implemented, the results are for reference only. The Council believes that the upgrading proposal would not only facilitate consumers to make more energy-saving and environmentally friendly option, but also encourage manufacturers to develop products with better performance.

The safety test conducted by the EMSD found inadequacy in the user manual of 4 models for lacking the warning message relating to not allowing children to play with the appliance. The Council reviewed the ease of use of all the models and found that only 2 provided English user manual; 4 models did not have cover lid over the air ventilation grill, causing dust to fall in the grill. However, all models were equipped with an auto switch-off timer; 8 models provide auto switch-on timer; 1 model could even be operated remotely by a mobile device; 1 model came with an extension hose for drying the wardrobe and shoes.

Air Purifying Performance

The air purifying performance of 2-in-1 air purifying dehumidifier was tested for its first time in order to measure its air purifying speed and energy efficiency. The test revealed that the air purifying speed of 4 models varied significantly, the models with the highest and lowest speed in removing cigarette smoke, dust and pollen varied by 2 times, 1.3 times and 1 time respectively; of which 1 model was found slow in removing particulate matter, rated only 2.5 points. All models were found being able to reduce formaldehyde concentration in the air though its purifying speed was rather low, rated only 2 to 2.5 points. The energy efficiency of model set in air purifying mode was just fair, rated 3 or 3.5 points.

Consumers are advised to take note of the retail price and the frequency of changing the filter. Estimated based on the information provided by retailers, the accumulated expenditure of all models ranged from $4,798 to $6,340 for the first 5 years, and from $5,178 to $7,330 for the first 10 years. As the filter should be changed regularly, consumers should also consider the cost of changing filters in the long run when they consider buying 2-in-1 air purifying dehumidifier.

When purchasing and using dehumidifier, consumers should:

-Make reference to the energy factor, dehumidifying capacity and energy efficiency grading listed on the energy label, but not the claimed performance under the manufacturers’ test environment. The higher the energy factor of the models with the same dehumidifying capacity representing better energy-saving power; while the higher the dehumidifying capacity, the faster its speed;

-Consider one’s living environment and personal needs in choosing a suitable dehumidifier. Household with larger area, in closer proximity to seashore or more humid environment may opt for model with higher dehumidifying capacity;

-If choose 2-in-1 air purifying dehumidifier, need to consider the cost of changing filters in long run;

-Different manufacturers set different deadlines for spare parts storage, consumers should carefully check the relevant maintenance period and spare parts storage period before purchasing, and take note that there may be no maintenance due to shortage of spare parts after the lapse of the spare parts storage period and may have to buy a new dehumidifier;

-Pay attention to the implementation of new grading requirement in order to choose a more energy-saving and environmentally friendly product.

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