Mechanical Systems: Targeting Water Efficiency
Part 3: Water Heaters: How to Get Hot Water Quickly
Water Heaters: How to Get Hot Water Quickly
By James Piper, P.E. - July 2011 - HVAC
Traditional domestic water-heater systems use a centrally located boiler connected to a piping system to distribute hot water to its point of use. In medium-sized and large facilities, the system typically includes centralized storage tanks and circulation pumps.
The biggest drawback of these systems tends to be the response time to get hot water. In systems without circulation pumps, end users might have to run water for up to a minute before they get warm water. Even in circulating systems, users might have to run water for too long before they get warm water. In both cases, running the water results in additional water and energy costs.
An alternative to the traditional centralized system is the point-of-use system. In this system, technicians replace the central water heater with multiple, smaller water heaters located throughout the facility, located as close as possible to the point of use. With water heaters located at the point of use, the system's response time is much shorter, and energy losses associated with the centralized system's piping are much lower.
Controlling water use in building systems is not a one-time effort. Vigilance is essential. Managers must track and review metered readings regularly, and technicians must inspect and adjust equipment regularly. Managers also will have to review modifications to the building and its mechanical systems to ensure they comply with the organization's water-conservation strategies.
James Piper, P.E., is a national consultant based in Bowie, Md. He has more than 25 years of experience in facilities maintenance and engineering management.