The standard “NOM-003-ENER Thermal efficiency of water heaters for domestic and commercial use - Limits, test methods and labeling”, published under the Official Mexican Standard (NOM), describes the minimum thermal efficiency levels that water heaters for domestic and commercial use must meet and the test methods that must be used to verify such compliance. It also defines the requirements that must be included in the user information label and the procedure for assessing the compliance of these products.
This standard applies to domestic and commercial water heaters that use liquefied petroleum gas or natural gas as fuel and that provide hot water only in the liquid phase, imported, manufactured or marketed in the United Mexican States. Water heaters having a heat load greater than 108,0 kW, an absolute working pressure greater than 600 kPa or a water temperature greater than 87,0 degrees (360,15 K), those considered as boilers, and components, parts and spare parts of domestic and commercial water heaters that use liquefied petroleum gas or natural gas as fuel and that fall within the scope of this standard are excluded from the scope of this standard.
The preparation of this standard responds to the need to catch up with technological reality and update the features specified in the standard in order to increase energy savings and ensure the protection of energy resources. It is also aimed to protect users from low-quality products that may enter the national market.
Water heaters covered by this standard are classified as follows:
The thermal efficiency of water heaters within the scope of this standard must be at least the value specified in the table titled “Minimum thermal efficiency for domestic and commercial water heaters” and must be determined according to the test method defined in this standard.
The standby gas consumption value obtained during the test must be no more than 10 percent higher than the value declared on the thermal efficiency label. The standby gas consumption is determined in accordance with the principles defined in this standard.
The test methods defined in this standard allow the thermal efficiency of water heaters to be verified by measuring the energy released by the fuel used to raise the temperature of the water and by measuring the gas consumption of the heater in standby mode over a 24-hour period.
The measuring instruments, equipment and devices specified in this standard represent the minimum requirements for the performance of the tests and may be replaced by other equivalent devices or devices with superior metrological properties that enable the test result to be obtained in the specified units or values. Thermal efficiency tests are carried out using the kettle and measuring instruments listed in the table given in the standard.
Water heaters designed to stand independently on a pedestal must be mounted on a wooden platform with a thickness of at least 2 cm covering the total area of the heater base. It must have three supports with a width of at least 5 cm, a depth of 10 cm and a height of 10 cm. Wall-mounted water heaters must be supported by a wall model covering the entire installation area of the water heater in accordance with the manufacturer's installation instructions. The structure must be made of wood with a thickness of at least 2 cm. The wooden platform and the simulated wall can be reinforced with a metal structure. Installation for storage water heaters, installation of rapid recovery water heaters and installation of instantaneous water heaters are shown in the figures given in the standard.
Tests shall be carried out in a room where the air velocity does not exceed 2,5 m/s and the ambient temperature is 20,0 degrees plus/minus 3,0 degrees. For ambient temperature measurement, a sensor shall be placed at the center point (vertical) of the heater and 600 mm plus/minus 10 mm from the heater body. The air velocity within the enclosure shall also be determined at the same distance.
The heaters must be connected to a water supply capable of delivering water at a temperature of 20,0 degrees plus/minus 2,0 degrees. The water heater water inlet and outlet pipes must be connected as appropriate. Quick-connect fittings may be used to facilitate assembly and disassembly of the piping arrangements.
The properties of the test gases used in the tests are given in the standard.
The capacity of the tested water heaters is determined in kilograms according to one of the methods given in the standard.
Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services are also provided to businesses in accordance with the "NOM-003-ENER Thermal efficiency of domestic and commercial water heaters - Limits, test methods and labeling" standard.
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