[Equest-users] chiller sequencing

[Carol Gardner]

Hi Joe,

The info is actually pretty robust, it just hasn't been covered for while
and no one seems to be using it much. So kudos to you. I am going to attach
a screen shot below, but also refer you to Volume 3 of the manuals. That's
where you'll find lots of in depth discussions. Some of the commands may be
slightly different in name and format but I think you'll be able to figure
them out.

Cheers,

Carol


 Volume 3: Topics <volume3topics.htm> > Central Plant
Components<centralplantcomponents1.htm>>
LOAD-MANAGEMENT and EQUIP-CTRL <loadmanagementandequipctrl.htm> > Examples
of EQUIP-CTRL and LOAD-MANAGEMENT
Sequences<examplesofequipctrlandloadmanagementsequences.htm>
Example 1:  Chiller Staging

Assume a central plant has three chillers:  200 tons, 400 tons, and 600
tons.  By default, the program will use the 200 ton chiller whenever the
load is in the range of 100-200 tons, the 400-ton chiller for loads in the
range of 201-400 tons, etc.

In this example, this is not the optimum control sequence, however, because
the 200 and 600-ton machines are newer and much more efficient than the
400-ton machine.  The following sequence will optimally load the newer
machines and reserve the 400-ton machine for periods of maximum load:

CHLR-CTRL = EQUIP-CTRL
TYPE               = COOLING
CIRCULATION-LOOP   = COOLING-LOOP

LOADS-THRU-1       = 2.4                  *Millions of Btuh*
CHILLERS-1         = (CHLR-200)

LOADS-THRU-2       = 7.2
CHILLERS-2         = (CHLR-600)

LOADS-THRU-3       = 9.6
CHILLERS-3         = (CHLR-600,CHLR-200)

LOADS-THRU-4       = 14.4
CHILLERS-4         = (CHLR-600,CHLR-200,CHLR-400)
..

The spacing between load ranges is for clarity only; as with all BDL input,
spacing has no effect on the meaning of the input.

Some types of equipment, such as chillers and cooling towers, have a
capacity that varies hourly in accordance with ambient temperature and/or
other conditions. Therefore, it often makes sense not to have to specify a
fixed LOADS-THRU range, but to allow the range to default to the hourly
capacity of the equipment listed within the range. If you do not specify the
LOADS-THRU keyword, the value will default to the hourly capacity. The
following is equivalent to the example above, but takes into account the
varying hourly capacities:

CHLR-CTRL = EQUIP-CTRL
TYPE               = COOLING
CIRCULATION-LOOP   = COOLING-LOOP

CHILLERS-1         = (CHLR-200)
CHILLERS-2         = (CHLR-600)
CHILLERS-3         = (CHLR-600,CHLR-200)
CHILLERS-4         = (CHLR-600,CHLR-200,CHLR-400)
..

Also, while the above input works, it uses more keywords than is needed;
also for clarity.  The following input is equivalent:

CHLR-CTRL = EQUIP-CTRL
TYPE               = COOLING
CIRCULATION-LOOP   = COOLING-LOOP

CHILLERS-1         = (CHLR-200)
CHILLERS-2         = (CHLR-600,CHLR-200,CHLR-400)
..

This input, while shorter than the previous, is also somewhat overspecified
because the default sequencing for the EQUIP-2 list is the order entered.
In other words, the CHILLERS-SEQ-2 did not need to be listed in this
example.

If sequencing is not specified, equipment is started in the order listed.
The following examples are equivalent, and illustrate how sequencing works:

   LOADS-THRU-2       = 999.
CHILLERS-2         = (CHLR-600,CHR-200,CHLR-400)

   LOADS-THRU-2       = 999.
CHILLERS-2         = (CHLR-600,CHR-200,CHLR-400)
CHILLERS-SEQ-2     = (       1,      2,       3)

   LOADS-THRU-2       = 999.
CHILLERS-2         = (CHLR-200,CHLR-400,CHLR-600)
CHILLERS-SEQ-2     = (       2,       3,       1)

In all these examples, CHLR-600 starts first, followed by CHLR-200, followed
by CHLR-400.  To force CHLR-600 and CHLR-200 to always start and run
together, give them the same sequence number:

   LOADS-THRU-2       = 999.
CHILLERS-2         = (CHLR-200,CHLR-400,CHLR-600)
CHILLERS-SEQ-2     = (       1,       2,       1)




On Thu, Mar 3, 2011 at 11:58 AM, Fleming, Joe <joe.fleming at tlc-eng.com>wrote:

> How would one sequence chillers in the following way?
>
>
>
> Chiller 1 - up to 150 tons
>
> Chiller 2 - 150-350 tons (Chiller 1 is off in this range)
>
> Chiller 1&2 - 350-500 tons
>
>
>
> The Load range tab provides a "max load", but I believe that when I move to
> step 2 that equest is going to keep both chillers on.
>
> i.e. for an input such as;
>
> Chiller-Seq-Max Load
>
> Chiller 1 - 1 - 150
>
> Chiller 2 - 2 - 350
>
>
>
> Should you utilize the different "Load Ranges" here?
>
> The help file for this sections is not as robust as the other help
> sections.
>
>
>
> Thank You
>
>
>
>
>
> *Joe Fleming*
>
> *E.I., LEED AP BD+C, BEMP*
>
> *Mechanical Engineer II*
>
>
>
> *TLC Engineering for Architecture
> **Your 2030 Challenge Partner***
>
>
>
> 800 Fairway Drive, Suite 250
>
> Deerfield Beach, FL 33441-1816
>
>
>
> phone:
>
> 954-418-9096
>
> fax:
>
> 954-418-9296
>
> direct:
>
> 954-418-4591
>
> website:
>
> www.tlc-engineers.com
>
>
>
> [image: http://www.tlc-engineers.com/images/TLC_Sig_Loc_Block.gif]<http://www.tlc-engineers.com/>
>
>
>
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-- 
Carol Gardner PE
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