CIBSE reference

[SomeDaySomeHow]

thread403-320544

A question to Waramanga: "According to my CIBSE reference, a three way valve on a coil needs a balancing valve on the bypass line along with one in the return line back to the chiller/boiler. That bypass valve gets set to provide the same dP as the coil when in full bypass mode."

Can you tell me what the CIBSE reference is that you were referring to in the previous thread (copied above)? I would like to know the title of the reference so that I can buy a copy from CIBSE to study - I looked up a few HVAC books that I have but none tells about bypass balancing valve. Thank you for your help.

 

[ChasBean1]

SomeDaySomeHow, Waramanga is like me – gives good answers but logs on sporadically due to life’s other requirements. His last time was over a month ago.

Balancing valves in a 3-way bypass line or in a coil return line are limiters. They won’t normally play any part unless there is a problem, such as all coil valves fail open, CHW temperature gets too warm, etc.

At that point, they hold the flow to a certain limit if/when the respective control valves serving that coil are wide open.

To me, the three way BYPASS circuit setter should be throttled to about ¼ of the coil design flow. This would assure pump minimum flow while reducing pump energy in non-demand situations.

 

[SomeDaySomeHow]

Thank you ChasBean1, but because of my ignorance, I still do not have full understanding - maybe no understanding at all. Perhaps I should tell how I came across the question about bypass balancing valve installed in conjunction with 3-way control valve. I was trying to get myself understood how various parts in a chilled water coil fitting (see attached the diagram) work as a whole. When you have a chance, can you take a look at the diagram and see if you can make sense of it for me? I would greatly appreciate it.

 

[Wilbur55]

Seriously? A pptx file?!

This could have been done with a screen capture saved to png format.

Markups can be done in any number of image editing programs.

Then viewing your image would have been one click away within the browser.

Instead, I fired up a behemoth cripple-ware Microsoft viewer to see a single image!

Wow!