Hello All,
I have a question regarding loops in eQuest. The building I am modeling has water source heat pumps and other water cooled air conditioning units. Per the building design all of these are on the same hot water loop (boilers) and condenser water loop (cooling towers). However, in eQuest when I specify the heating source for the heat pumps as "DX Coils (Heat Pump)" a WLHP loop is created. This then requires its own boiler and cooling tower. What would be the best practice to model this correctly? Two options I have considered would be to change all the heating sources of the heat pumps to "hot water loop", but do not think it will provide the same outputs. The other option was to keep the two loops and size each boiler as a fraction with respect to the capacity of the units. Are either of these correct or is there a better method to properly model Water source heatpump and water cooled AC units?
Thank you,
Patrick Krystyniak
Stantec
315 Park Avenue South 17th Floor, New York NY 10010-3650
Phone: (212) 330-6174
Fax: (212) 695-1898
patrick.krystyniak at stantec.com
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Here's some reference material - do a "find" for circulation-loop on page 229 (236 of the PDF) which will explain the type of loops used in eQUEST and how these compare to the naming/purpose in industry.
http://doe2.com/download/DOE-22/DOE22Vol2-Dictionary_48r.pdf
eQUEST has the "WLHP" type in order to define the behavior for heating and cooling on the terminal unit side and allowing the appropriate controls to be used at association with HP, towers, and boilers.
You need to use the loop of type WLHP to have the functionality of the temperature control with a max and min, and you can attach both boilers and cooling towers to this type of loop. (You cannot attach a cooling tower to a loop that is the type heating.)
Commonly from the design engineering side would be that one common piping loop is the condenser loop (in eQUEST the WLHP type loop) and then the boiler and cooling tower can be attached to that loop as primary or secondary connections. That definition will occur within their own dialog screens depending how you specify the pumping configuration.
So I think what you need to do from the description is go to the boilers that you already defined and associate them to the WLHP loop, and delete the hot water loop - this would be used for a heating system such as fan-coil units, AHU heating coils, perimeter heating, or reheat coils for instance.
David
David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
Grumman/Butkus Associates
David,
Thank you for the response. After reading from the reference material for WLHP's, it seems as if I am able to attach any cooling unit with a water cooled condenser to this loop. I believe this will solve the issue related to modeling only one condensing water loop for both heat pumps and other water cooled units. On the other hand, when I delete the hot water loop, I no longer have any heat source for the types of units you listed (fan-coil units, AHU heating coils). Am I understanding the methodology you described correctly?
Thank you,
Patrick Krystyniak
Stantec
315 Park Avenue South 17th Floor, New York NY 10010-3650
Phone: (212) 330-6174
Fax: (212) 695-1898
patrick.krystyniak at stantec.com
The content of this email is the confidential property of Stantec and should not be copied, modified, retransmitted, or used for any purpose except with Stantec's written authorization. If you are not the intended recipient, please delete all copies and notify us immediately.
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