Step into the future with Cobra

2016 Cobra Product Design Challenge

By Kelly-Ann Prinsloo

The 2016 Cobra Product Design Challenge provides industrious designers with a chance to make their mark on the plumbing industry.

Read more: Step into the future with Cobra

The importance of a common installation manual

By: Vollie Brink

It’s not enough to simply supply the industry with design manuals – this needs to be accompanied by an installation manual

Read more: The importance of a common installation manual

Certification key tool for building smart cities

By: Neeta Sharma

The quality of products and the people installing them plays a significant role in assuring efficiency in the smart cities of the future

Read more: Certification key tool for building smart cities

The silent temperature

By: Enrique Gonzalez

The uniform plumbing code continues to evolve with regard to temperature in water heaters

The Uniform Plumbing Code (UPC) governs the construction, location, and installation of fuel-burning and other types of water heaters.

The UPC defines a water heater, or water heating boiler, as an appliance designed primarily to supply hot water for domestic or commercial purposes and equipped with automatic controls limiting water temperature to a maximum of 210°F (98°C). The water heater thermostat is a device used to set the water temperature within the holding tank, and the UPC does not recommend or mandate a temperature setting for the thermostat, thus making it a ‘silent temperature’ setting. The UPC does, however, contain regulations for minimum requirements that focus on the health, safety, and welfare of the public by mandating specific requirements for the water heater and plumbing fixtures.

The UPC addresses comprehensive installation requirements for water heater safety devices and water heater appliances while referencing the appropriate nationally recognised standards where applicable. There are three water heater safety devices required by the code: the first being a temperature-limiting device designed to prevent the heated water from exceeding 210°F (98°C) by automatically shutting down the energy source and preventing the water heater from becoming a steam-boiler; the second water heater safety device is a vacuum relief valve designed to prevent siphonage within the tank that can result in emptying of the tank (possibly creating steam in the tank), and can even cause the tank to collapse; the third safety device is a pressure relief valve designed to relieve excess pressure, usually at 150psig for residential water heaters. Note that an expansion tank does not take the place of a pressure relief valve device, and that an expansion tank is required when a water system contains a check valve, backflow preventer, or other normally closed device that prevents dissipation of building pressure back into the water main.

A water heater designed for residential or commercial purposes is typically set at 120°F (48°C) from the factory, but what temperature should the water heater be set to when installed? Again, the UPC is silent on the temperature setting for the water heater thermostat and states that water heaters shall be installed in accordance with the manufacturer’s installation instructions. The water heater manufacturers typically recommend a thermostat temperature setting.

Unfortunately, there is no perfect temperature setting as an overlap of temperatures is required for the health, safety, and welfare of the end users. When the water temperature is set too low, the water can create a perfect environment for Legionnaires’ disease. There are documented instances of health hazards associated with water storing vessels set at temperatures known to ‘amplify’ bacteria growth. According to the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Guide 12, legionellae have been recovered from cold water, and the temperature range favourable for amplification of bacterial growth is 77°F (25°C) to 108°F (42°C). Furthermore, ASSE indicates that the temperature of the water within a water heater is recommended to be set between 135°F (57°C) to 140°F (60°C) in order to minimise the growth of harmful bacteria found in water. However, these high temperatures put the public at risk for scalding, thermal shock or both. According to the Engineering and Science Division of the United States Product Safety Commission, it takes one minute to receive a first-degree burn at 122°F (50°C), and it takes two seconds to receive a first-degree burn at 140°F (60°C).

Read the full feature in Plumbing Africa February 2016,page 27.

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