Variable Primary Flow Chilled Water System Sequence of Operation 2

[yusef814]

I am designing a chilled water system for an administrative building. It will have a variable primary flow (single loop) with two parallel and equally-sized air-cooled chillers with one set (2 duty, 1 stand-by) variable speed pumps.

I’m hoping that someone could lead me in finding a standard Sequence of Operation for this system. I couldn't find help from the references I currently have.

Thank you all.

 

[Wareagl487]

Automated Logic has an online control specification generator that covers a wide variety of system types. I use it quite often as a good starting point then editing it slightly for my particular need.

http://www.automatedlogic.com/guide-specification/

Andy W.

 

[ChasBean1]

Here is a standardized sequence for a variable primary flow system. Please don't share this with anyone.

The primary pump VFD modulates to maintain loop differential pressure set point, at some point near the end of the loop. Across the supply and return loops, located somewhat near the pumps, there is a minimum flow bypass line and control valve sized for about 1/3 to 1/2 design flow. The valve will normally be closed. If, during one chiller operation, the flow through a single chiller becomes too low, as sensed by a flow meter or DP transducer across the operating chiller, the control valve will modulate to maintain minimum flow.

The DP bypass valve should be fast acting but tuned; the pump VFD should be fast acting but tuned. For chillers in parallel, each chiller isolation valve should be very slow acting.

 

[yusef814]

Thanks, Wareagl487 your suggestion helps a lot.

Chasbean1, you can count on me. This kind of information does not come everyday even to a seasoned designer. Thank you.

 

[ChasBean1]

Haha - no problem. Although you're probably looking for more detail...

 

[marcoh]

This may help

http://www.trane.com/commercial/library/vol31_4/adm_apn005_en.pdf

http://www.trane.com/cps/uploads/userfiles/educationalresources/adm_apn033en_0109.pdf