We have a project that is an industrial facility, it shares the CHW distribution piping between the comfort system and the process system.
We are informing the CxTeam that it is required to have balancing means at all connected devices, and/or at a minimum at all comfort devices and each branch going out to the process part of the CHW distribution piping.
The owner has CHW flow diagrams indicating the required gpm for their process, including future expansion. Our "requirement" to the owner is to install balancing or flow limiting devices at the process branch piping to be able to meet the requirements of section 6.4.5 and subsequently 6.7.2 of ASHRAE Standard 90.1-2007.
Any comment regarding our "requirement" is appreciated. We do not want to obligate the owner to do something that is not a Mandatory Requirement, but we also want to make sure that these are met.
Thanks
Jorge
Jan Wei
Director of Commissioning & Critical SystemEdwards & Zuck
44 thumbs up
November 13, 2015 - 1:02 pm
Hi Jorge,
Based on the information provided, my understanding of the question is if the balancing device is required on the process branch which is sharing the same system as the comfort system. In a hydronic system any modification or addition to the existing system will modify the system pressure dynamic, and all terminal devices should have balancing device, unless the entire system is a reverse piping configuration, to ensure proper flowrate. So I would recommend to the owner to investigate the terminal unit at the process equipment to ensure there are balancing devices so the entire system can be balanced during TAB phase.
Scott Bowman
LEED FellowIntegrated Design + Energy Advisors, LLC
LEEDuser Expert
519 thumbs up
November 19, 2015 - 1:52 pm
I do not have a copy of 90.1 handy, so will take your word on that. However, you are also as the CxA to be guiding clients to best practices, and the use of balancing valves is best practice. There is debate in the industry on flow limiting devices, as they always impose a pressure drop no matter what, but do a great job of providing proper flow. But you have to have a means of balancing the systems, especially with a process load combined with future capacity built into the system. You are not asking or recommending anything that is outside the typical best practice of system installation for hydronic systems.