Trying to do the load calculations for (3) 300 ton air-cooled chillers... The Datasheet indicates an MCA of 557A. with a circuit beaker rating of 700A. Do all three of these get treated as 100% continuous load, with the appropriate individual conduit and wire sizes, or is there an applicable demand factor that can be used? The Mechanical Engineer has indicated that all (3) of these may indeed be running at the same time....
Demand Factor for (3) Chillers
- Thread starter Turk1957
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electrofelon
Senior Member
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- Cherry Valley NY, Seattle, WA
First note that there isnt a continuous load adder for HVAC equipment. With multiple units, you will have some un-necessary fudge in there because you will have 125% of the largest motor in each unit applied. I believe you could theoretically add up all the loads in all of the units and only apply the 125% of the largest, but i am not really sure if that is generally done.
ron
Senior Member
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- New York, 40.7514,-73.9925
No demand that I know of as mentioned except ........
There is an efficiency to be had if the 3 chillers are cooling the same liquid, running in parallel (mechanically) and the mechanical load is less than 3 chillers worth.
The manufacturer can run a calculation how they run electrically when unloaded to some %
There is an efficiency to be had if the 3 chillers are cooling the same liquid, running in parallel (mechanically) and the mechanical load is less than 3 chillers worth.
The manufacturer can run a calculation how they run electrically when unloaded to some %
kwired
Electron manager
- Location
- NE Nebraska
I agree with other replies. If the unit is needed to accomplish the total cooling load, I think you must consider 100% of it's rating.
If it is only there as a standby unit, you may be able to only include the necessary VA needed for the actual calculated cooling load. This would have to be at AHJ discretion though, as I don't see NEC taking that consideration, unless there is some method used to assure it doesn't run in addition to the other load(s).
If it is only there as a standby unit, you may be able to only include the necessary VA needed for the actual calculated cooling load. This would have to be at AHJ discretion though, as I don't see NEC taking that consideration, unless there is some method used to assure it doesn't run in addition to the other load(s).
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