The commissioning of plumbing systems is not in every project’s scope, but when it is, the domestic hot water (DHW) system is often the first system included. Typically, the DHW system includes recirculation piping and an associated pump to ensure the water being recirculated throughout the building is of adequate temperature and is available at served fixtures relatively quickly. The commissioning effort for DHW systems will naturally focus on the installation and operation of the water heater and recirculation pump. However, some recent projects have taught me that I also need to watch for the inability to isolate individual DHW risers.
In recent years, I’ve been involved in many high-rise residential buildings. My involvement has never been new construction commissioning. In our locale, the project delivery process for these types of buildings almost always “value engineers” out such services. More effort and money are spent on making those new condos look pretty than on making the building systems function correctly. As such, we usually are called in a few years later for retro-commissioning services when building operations are not quite panning out. One of the common systems we find ourselves troubleshooting is the DHW recirculating system.