Maintaining Minimim Chiller Flow using a Cla-Val
Maintaining Minimim Chiller Flow using a Cla-Val
(OP)
I'm asked to resolve a problem where a chiller isn't receiving it's minimum flow at all times which is causing problems. The system serves several unit ventilators each with 2-way on/off valves. When the units aren't calling for cooling, the valves are closed.
The chiller has a minimum flow requirement of 119 GPM, and they want the chiller to operate even if only 1 unit ventilator is calling, which would be only about 6 GPM.
A 1-1/4" Cla-Val was installed about half-way down the piping system. It is a model 50-01, and from what I can find on their web site, it can pass a maximum continuous flow of 93 GPM.
This is obviously short of my required 119 GPM, but I don't understand how the Cla-Val operates. I'm not sure how it should be set to bypass flow when needed and not bypass it when the unit ventilators are calling. The system pump is rated at 160 GPM @ 80'.
Any suggestions on the best resolution? Should I increase the Cla-Val size? Should i add a second one? Should I do something else entirely? Where in the piping system should I put it?
Thanks for your help
The chiller has a minimum flow requirement of 119 GPM, and they want the chiller to operate even if only 1 unit ventilator is calling, which would be only about 6 GPM.
A 1-1/4" Cla-Val was installed about half-way down the piping system. It is a model 50-01, and from what I can find on their web site, it can pass a maximum continuous flow of 93 GPM.
This is obviously short of my required 119 GPM, but I don't understand how the Cla-Val operates. I'm not sure how it should be set to bypass flow when needed and not bypass it when the unit ventilators are calling. The system pump is rated at 160 GPM @ 80'.
Any suggestions on the best resolution? Should I increase the Cla-Val size? Should i add a second one? Should I do something else entirely? Where in the piping system should I put it?
Thanks for your help





RE: Maintaining Minimim Chiller Flow using a Cla-Val
If that's the only bypass it just sounds like you are short on bypass. It's hard to tell you exactly what should be done without seeing a schematic of the piping. You could add a small bypass to the end of each unit ventilator loop with manual balancing valve and then reset your automatic valve so you are getting min. flow when all 2-ways are closed. Or you could put a bigger bypass in, that isn't going to be cheap though.
RE: Maintaining Minimim Chiller Flow using a Cla-Val
http://www.cla-val.com/animation.cfm and find the 50-01 valve
RE: Maintaining Minimim Chiller Flow using a Cla-Val
I assume the wish is to prevent the compressor from start and stopping all the time at minimum load.Proposed solution:
1.mount an on/off bypass valve on each ventilator unit with an orifice.the delta P of the ventilator circuit with the on/off valve to be the same as the on/off bypass valve with the orifice.
2.improve the capacity control of the compressor by using a VFD or a two speed motor
RE: Maintaining Minimim Chiller Flow using a Cla-Val
Determine which units run the most until you get around 120 GpM worth. Outfit each of those with a correctly sized Hays Mesurflo (I have used thousands) and 3-way valves instead of the two-way. If no other units are running, you will have just enough to keep the chiller running.