[Equest-users] Chiller Sequence

[Carol Gardner]

Hi Rick,

You should be able to do this using a combination of EQUIP-CTRL  and
LOAD-MANAGEMENT commands. If you Google Equip-Ctrl you will get a link to a
thread on the list-serv with some good examples.

Carol

On Sun, Jul 3, 2011 at 3:56 PM, Routh Consulting Engineers <
routhconsultingengineers at charter.net> wrote:

> Can someone help me with the proper inputs for the following chiller
> sequence of operation. I have five 400-ton water cooled centrifugal
> chillers, three of them have variable speed drives, the other two just inlet
> vanes for capacity control. For loads up to 360 tons, one of the variable
> speed chillers operates. For loads up to 720 tons, two of the variable speed
> chillers operate, but one of them at constant full load and the other
> responding to variations in loop loads. This sequence continues similarly at
> greater loads, basically one chiller handles loads up to about 80% of its
> capacity, at which time another chiller is added, but only the last one to
> come on modulates to the load, while the others operate a full load. In
> reading the program manuals for equipment control, it appears that you can
> establish the appropriate sequence, but once additional chillers come on,
> all modulate to handle the load in proportion to their capacities, which in
> my case because all chillers are the same size, would handle equal portions
> of the loads. I am modeling an existing chilled water plant that is operated
> in this manner, and one of the things I’m looking at is the savings of
> indeed operating them equally loaded when multiple chillers are needed. The
> variable speed chillers in particular operate at their highest efficiency in
> part load ranges, and it’s intuitively obvious that operating two of them at
> a mid-range part load will be more energy efficient than operating one at
> full load and one at a small part load, but my client would like to quantify
> this before changing his control sequences. Thanks in advance for any
> replies.****
>
> ** **
>
> Rick Routh****
>
> ** **
>
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-- 
Carol Gardner PE
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