65% Gas Water Heaters Performed Well but Price Could Differ by Twofold Support Inclusion in Mandatory Energy Efficiency Labelling Scheme for Sustainable Consumption

14 January 2021
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6成半气体热水炉表现佳惟售价可相差逾倍   倡纳入强制性能源效益标签计划支持可持续消费

In winter, nothing is quite as soothing and reinvigorating as a hot shower after a long tiring day. The Consumer Council, in collaboration with the Electrical and Mechanical Services Department (EMSD), tested 20 models of domestic gas water heaters. 13 models were rated 4.5 out of 5 points overall, yet huge price differences were found. The highest ($9,110) and lowest ($4,380) priced models within the same gas type and with the same declared hot water production capacity showed more than a twofold price difference. As gas water heaters are durable home appliances that often cost several thousand dollars apiece, the Council reminds consumers to compare the cost-effectiveness of the products to get the best value for money. In terms of safety, 1 towngas water heater sample failed to pass part of the safety tests as its pressure relief valve setting did not match with its labelled highest applicable water pressure. Another towngas water heater sample had its difference between the measured and declared maximum heat input exceed the recommended acceptable tolerance of the Chinese national standard. The difference between the measured and declared hot water production capacity of the same sample also failed to meet the standard requirement. The Council urges manufacturers to improve the product quality and ensure the accuracy of the labelled content to enable consumers to make informed choices.

20 gas water heater models from 16 brands were tested, all models bearing a “GU” safety mark issued by the EMSD, including 11 towngas water heaters with claimed hot water production capacity of 10 to 16.8 litres per minute for 25°C temperature increase; the other 9 models were LPG water heaters with claimed hot water production capacity of 10 to 13 litres per minute for 25°C temperature increase. The test referenced the Chinese National Standard GB 6932 and test items included heat input, thermal efficiency, hot water delivery performance and accuracy of displayed water temperature. In addition, safety tests were conducted based on the EMSD’s “Domestic Gas Appliances Basic Safety Assessment” (TA2) specifications while the ease of use for each model was also evaluated.

The 20 models had huge disparities in terms of their retail price, with the appliance plus basic installation fee ranging from $3,500 to $10,060. However, among samples within the same gas type and with the same declared hot water production capacity, the cheapest model ($4,380) and another model which was over twice its price ($9,110) received the same good overall rating of 4.5 points, best among all models, proving that price does not always reflect quality.

When selecting gas appliances, safety is the top priority. In the water soundness test, 1 towngas water heater sample’s pressure relief valve was triggered open when 750kPa water pressure was applied, notwithstanding its claim of a maximum applicable water pressure of 1,000kPa, leaving room for improvement.

The combustion products discharge failure device of all models was tested against TA2 specifications, which requires gas supply to be automatically shut off within 60 seconds in the event of failure of discharge of combustion products. 1 towngas water heater sample became slightly deformed at the edges of the casing during the first test, despite being able to automatically cut off the gas supply within 10 seconds. The Council subsequently conducted the same test on 2 other samples of the same model and both passed the test.

The higher the heat input (commonly known as “gas consumption”), the greater the burning power. The maximum heat input measured for the 20 models ranged from 19.97 to 39.52kW, indicating a discrepancy of +8.2% to -13.1% compared to the respective claimed value. 3 towngas water heater samples and 1 LPG water heater sample showed a better degree of accuracy with merely ±2% variance between the measured and declared values of maximum heat input. However, 1 towngas water heater sample was tested to have a maximum heat input 13.1% lower than claimed, exceeding the ±10% acceptable tolerance recommended by the GB 6932 national standard.

The hot water delivery performance directly impacts the user’s comfort when taking a shower. The test scenario simulated the supplied water temperature of 15°C in winter and a water temperature of 40°C for the hot shower, thus measuring the actual hot water production capacity of the water heater with a 25°C temperature increase. Upon comparing the declared and actual performance of the samples, the 20 samples achieved a degree of accuracy of around 89% to 109% in terms of their hot water production capacity. 18 samples achieved over 95% accuracy, whereas the towngas water heater sample with the lowest accuracy (89%) claimed to have a hot water production capacity of 13 litres per minute, but only measured 11.6 litres per minute in the test. Its accuracy fell slightly short of the lower limit of the standard requirement (90%).

Test results showed that the gas water heater samples performed well both when heating up and reactivating. The standard recommends water heaters to heat up to an increase of 40°C within 35 seconds. Only 1 LPG water heater sample required 1 second more than the recommended limit to heat up the water, whereas the rest required 11 to 27 seconds. Besides, if the hot water tap is turned off during the shower and turned back on, generally the water temperature may see a sharp increase and return to the original temperature after a few seconds. The test revealed that all samples had a temperature rise of 6°C or less upon turning the hot water back on, with 14 samples having a maximum temperature increase within 2°C, complying with the standard recommendation (no more than 18°C).

The 19 samples with automatic temperature‐modulation function performed well in temperature control both when the hot water flow was adjusted and during steady flow. As for the remaining 1 towngas water heater sample which was not equipped with automatic temperature‐modulation function, a highest water temperature increase of 69°C was recorded while operating at the highest flame and water temperature settings, exceeding the standard recommended upper limit of 60°C. Consumers should pay attention to the water temperature displayed and adjust accordingly to prevent potential scalding hazard.

The thermal efficiency of all samples was tested based on the GB 6932 standard, one of the national standards recognised under the EMSD’s Voluntary Energy Efficiency Labelling Scheme (VEELS). The higher the thermal efficiency value, the higher the energy efficiency and the more energy-saving it is. The test results showed that all samples met the thermal efficiency requirements of VEELS (not lower than 82%), but considerable disparity still existed amongst the different samples’ performance: the thermal efficiency of 11 towngas water heater samples ranged from 84.8% to 93.3% while that for the 9 LPG water heater samples ranged from 87.1% to 92.3%. Based on this result, for the towngas category, the sample with the highest thermal efficiency can save around 6% energy than the sample with the same declared hot water production capacity but lower thermal efficiency; while for LPG water heater samples, the energy-consumption variance can be over 5%. The Council supports EMSD to include gas water heaters in the Mandatory Energy Efficiency Labelling Scheme (MEELS) instead of the current voluntary participation, and recommends to replace recognition-type labels with grading-type labels to encourage traders to introduce more energy-efficient products. The Council also urges traders to provide a longer product warranty period and lower the maintenance fee to extend the product life, in order to reduce waste and support sustainable consumption.

Consumers should pay heed to the following when purchasing and using gas water heaters:

  • Ensure that the product bears a “GU” safety mark which signifies approval by the Gas Authority of EMSD;
  • Follow the instruction manual when operating the water heater, and remember to switch it off after each use;
  • All installation, replacement or repair work on gas appliances must be carried out by a registered gas installer employed by a registered gas contractor. Moreover, conduct a safety inspection once every 18 months;
  • Stop use immediately if the heater shows any abnormality, and contact the product supplier or registered gas contractor to check or repair it;
  • If you suspect a gas leak, turn off the main gas supply under safe circumstances and inform the registered gas supply company immediately to handle the issue on-site. Do not use any electronic products until you are far from the site with suspected gas leak;
  • If the water supply was temporarily suspended at home, sediments may have accumulated inside the pipes and may affect the normal operation of the water heater. In this case, turn on the cold water to flush out the sediments until the water runs clear before using the water heater.

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