[Equest-users] chiller sequencing
Fleming, Joe
joe.fleming at tlc-eng.com
Thu Mar 3 12:41:56 PST 2011
This is great Carol.
Thanks!
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<http://www.tlc-engineers.com/>
[cid:image001.gif at 01CBD9B9.87024080]<http://www.tlc-engineers.com/>
From: Carol Gardner [mailto:cmg750 at gmail.com]
Sent: Thursday, March 03, 2011 3:26 PM
To: Fleming, Joe
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] chiller sequencing
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<mailto: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<http://www.tlc-engineers.com/>
[cid:image001.gif at 01CBD9B9.87024080]<http://www.tlc-engineers.com/>
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Carol Gardner PE
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