The Importance of Drain-Water Tempering

July 1, 2012
Water exceeding 140°F compromises pipe integrity, imperiling personnel, property

According to the International Plumbing Code and most state codes, the temperature of water entering a sewer system must not exceed 140°F. Discharges or “draw water” hotter than 140°F can compromise the integrity of drain lines, causing leaks and even total failure.

Boilers, humidifiers, autoclaves/sterilizers, and commercial-kitchen equipment produce drain water exceeding 140°F. Many facilities managers and plumbing professionals either are unaware of this or do nothing about it, putting personnel and property at great risk and exposing themselves to the possibility of a failed inspection, fine, and/or business interruption/delay.

Last year, for instance, the owner of a chain of coffee shops was preparing to open a brand-new property in New York. The finishing design touches were complete, staff was hired, inventory was ordered, and marketing materials were created; all that was left was the plumbing inspector making his rounds. The inspector discovered water from the shop’s espresso machine was entering the drain lines at 148°F, 8°F above the specified limit. By the time corrections were made and the property was re-inspected, two weeks had passed. To the owner, the delay was time-consuming and costly.

Cooling drain water to below 140°F is relatively easy and can be accomplished by several means. One involves a valve opening and closing an attached cold-water line. There are two types of valves:

  • Electrically actuated. An electrically actuated valve is controlled by an electric current through a solenoid. A temperature switch/thermostat makes or breaks the electrical circuit, signaling the solenoid to open or close the valve.
  • Mechanically actuated. Mechanically actuated valves do not require an external power source. A thermal actuator senses when hot drain water is present. When hot water heats the actuator, the valve opens, releasing cold water. As drain-water temperature decreases, the valve starts to close. This modulating feature conserves water compared with a solenoid valve, which is either open or closed.

Code-compliant drain discharges are necessary for effective operations and management. Temperature-control valves are a cost-effective, efficient, and painless way to ensure the safety of your employees, the integrity of your plumbing system, and that your property passes inspection. By adding a temperature-control valve to your commercial equipment, you can make sure you and your staff do not end up in hot water.

Did you find this article useful? Send comments and suggestions to Executive Editor Scott Arnold at [email protected].

Vice president of engineering for Therm-Omega-Tech Inc., designer and manufacturer of self-actuating temperature-control valves, Nick Tallos has more than 40 years of engineering experience. He holds a bachelor’s degree in mechanical engineering from Villanova University and is a member of the International Association of Plumbing and Mechanical Officials, ASME, and The International Society of Automation.