Hydraulics question

mferrer

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Uploaded Jan 7, 2025201.34 KB

I was in a situation and piped out a Chilled water return header feeding 4 coils. I mistakenly connected 2 out of the 4 returns directly opposite each other (as per the sketch). The other 2 coils are tied in separately further down on the vertical header.

Is this a problem? Will it create turbulence that will negatively effect the flow?

Thank you in advance for any comments!

ScottSecor

I don't think it will be a problem with that large of a header.

hot_rod

Any idea of the flow rate on the branches, what size pipe?

The 6" main may act as a hydraulic separator, should not be an issue.

mferrer

There are a total of 4- 2" branches tied into the 6" header. Not sure of the flow rates. Each branch has a Hays balancing valve and a ball valve.

hot_rod

2” steel pipe, around 42 gpm at 4 feet per second velocity

6”, around 360 gpm

Are there checks at the coils?

If that main is flowing that kind of gpm, I doubt the branches across from one another will cause flow interference, if that is the concern

This wasn’t a primary secondary design? If so the S&R connections would be close coupled to the main

EBEBRATT-Ed

360 gpm is pretty low for 6" you should be fine.

hot_rod

Larger size pipe over 2" is often sized by pressure drop. Engineers are comfortable with flows up to 7 fps in steel pipe, intermittent flows up to maybe 10 fps. velocity noise, erosion and pumping power are the considerations.

This chart is a good quick reference.

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Uploaded Jan 8, 2025352.71 KB

mferrer

Thank you Hot Rod for the chart.

The 2" Hays Valves have a tag on them labeled: 45 gpm. The system is a secondary Chilled water system originating at 3-large plate exchangers getting the Chilled water from a Chiller Plant. They feed several large floors, each with an AHU (6" S & R headers) that have 4 chw coils (2" outlets). No check valves on the coil branch piping.

Thanks all- I am relieved to hear that there is a likelihood of problem-free operation. I will try to avoid Welding outlets across from each other in the future to play it safe.