IS 15558: 2005 outlines the guidelines for instantaneous domestic water heaters designed for LPG usage. This standard delineates the requirements for swiftly and continuously producing hot water for household needs utilizing liquefied petroleum gases (LPG) at a working pressure of 2.942 kN/m2 (30 gf/cm2). These appliances are regulated by water inlet control. It details the key structural and performance attributes of such water heaters and provides test methodologies for evaluating their performance. Notably, this standard does not pertain to water-boiling appliances.

An instantaneous gas water heater functions based on water draw-off, where heating occurs directly as water is used. Manufacturers are obligated to ensure that their products adhere to the standard's criteria regarding general, construction, and performance specifications. Here are some of the essential constructional and general requirements outlined.

All components in contact with water must be constructed from materials that prevent water pollution. It's imperative that all parts are manufactured and assembled to maintain consistent appliance performance over time. Brazed or welded joints are mandated for elements of water heaters directly exposed to heat. Additionally, the gas (heat) input to the pilot alone should not surpass 8 1/h under specified conditions of gas inlet pressure and temperature.

The appliance should feature a safety mechanism that automatically shuts off the gas supply if water flow ceases during operation. Materials utilized in constructing the water heater must exhibit resilience against regular wear and tear. The primary body of the burner, encompassing the mixer head, mixing tube, and burner head, should boast robust and enduring construction. Usage of metals with melting points below 510°C is prohibited. Copper and copper alloy components must undergo and pass the mercurous nitrate test (season cracking test) as per the methodology outlined in IS 2305.

TESTS

The subsequent test must be conducted for Domestic Water Heater.

• Protection against Electric Shock

• Mercurous Nitrate Test

• Immersion Test

• Water Soundness

• Gas Soundness

• Combustion Test

• Ignition and Flame Travel test

• FlashBack

• Hot water output Test

Each appliance should bear clear and permanent markings containing information as outlined in the standard. Adequate packaging is essential to prevent damage during transportation. Adherence to the stipulations of IS 15558:2005 enables certification under the Bureau of Indian Standards Act, 2016, and its associated regulations, allowing for the application of the Standard Mark (ISI Mark) on the product. Manufacturers are required to obtain a BIS license from the Bureau of Indian Standards to utilize the standard mark (ISI Mark), which is granted following a thorough evaluation of manufacturing infrastructure, quality control measures, testing capabilities, and production processes.

PROCESS FOR BIS ISI MARK CERTIFICATION