[Equest-users] Parametric runs and user expressions

David Reddy david at 360-analytics.com
Wed Feb 25 08:13:17 PST 2015
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John,
I think Julien pretty much summed it up.  A few additional comments:

  * The SYSTEM:TYPE = WLHP system is analogous to the TYPE = PTAC, in
    that this is a zonal system, i.e. each zone specified under that
    system is assumed to have an individual WLHP system, and the
    principal characteristics identified at the SYSTEM level (heat
    source, fan power, controls, etc) are assumed to apply to all the
    systems of the individual zones. PSZ and PVVT are single-zone
    systems, and it is assumed one system serves all the zones defined
    under that system, but only one zone is the control zone. All other
    zones simply get air supplied at the temperature dictated by the
    needs of the control zone, though zone heat sources can be specified.
  * Whenever modeling water-cooled DX systems, pay close attention to
    the DOE-2 performance curves.  They change primarily depending on
    whether the HEATING-SOURCE = HEAT-PUMP or not.  If this is the case
    in your project, you may need to make adjustments to your
    COOLING/HEATING-EIR values, as described in the Volume 2 HELP topic
    shown below.  In general, it is always important to ensure inputs
    like capacity and efficiency are coordinated with the PLR/Temp/etc
    points that the curves are normalized to.



On 2/25/2015 12:35 AM, Julien Marrec wrote:
> John,
>
> Even though I'm not a guru I'll give it a shot...
>
> Which type of zone HVAC system are you using for those 30 floors with 
> water cooled DX?
>
> If you look at the help entry for CONDENSER-TYPE:
>
> WATER-COOLED          The condenser is water cooled. You must attach 
> the condenser to a CIRCULATION-LOOP of TYPE = CW or WLHP via the 
> CW-LOOP keyword. For PSZ, PVAVS and PVVT, use of this value indicates 
> that a water-to-air heat pump (WLHP) is to be modeled.
>
> If you use PSZ, PVAVS and PVVT, you go to Cooling > Condenser, set 
> CONDENSER-TYPE = WATER-COOLED, then it will allow you to specify the 
> CW loop you want to use (CW-LOOP).
>
> If you use a PMZ or PTAC, even though you can select CONDENSER-TYPE = 
> WATER-COOLED, the GUI doesn't let you enter the CW-LOOP. I'm not sure 
> why, or if forcing it in the INP file achieves the right results. I'll 
> let one of them guru chime in on that :).
>
>
>
> 
>
> Best,
> Julien
>
> --
> Julien Marrec, EBCP, BPI MFBA
> Energy&Sustainability Engineer
> T: +33 6 95 14 42 13
>
> LinkedIn (en) : www.linkedin.com/in/julienmarrec 
> <http://www.linkedin.com/in/julienmarrec>
> LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr 
> <http://www.linkedin.com/in/julienmarrec/fr>
>
> 2015-02-25 7:20 GMT+01:00 John Aulbach <jra_sac at yahoo.com 
> <mailto:jra_sac at yahoo.com>>:
>
>     Hi Gang:
>
>     Got what should be a simple questions for the gurus..
>
>     I have a building which has two water cooled chillers on the first
>     4 floors. I also have about 30 floors of water cooled DX units. I
>     have a cooling tower and condenser loop set up for the 1st four
>     floors. I am having trouble setting up the water cooled loop for
>     the 30 floors of DX units.
>
>     Can anyone give me a simple example?
>
>     Thanks.
>
>     John R. Aulbach, PE
>
>
>     On Tuesday, February 24, 2015 8:15 AM, David Reddy
>     <david at 360-analytics.com <mailto:david at 360-analytics.com>> wrote:
>
>
>     Hi Julien,
>
>     I am pretty sure you can't use an expression to set a global
>     parameter; they are limited to being numeric or string (symbol)
>     values.
>
>     Unless I am mistaken on what you are after, you can change the
>     values of global parameters in parametric runs; see below for an
>     example.
>
>
>
>     To my knowledge, no, you can't reset or restore defaults using
>     parametric runs, but I can't say I've ever investigated this.  You
>     can use expressions that are dependent on a global parameters to
>     set a keyword value to unused or no_default. For example:
>
>     {if(#pa("901 HVAC Flag") ==1)
>     then 45
>     else unused
>     endif}
>
>     -David
>
>
>     On 2/24/2015 6:48 AM, Julien Marrec wrote:
>>     Hi,
>>
>>     Is there a way to implement the following::
>>
>>     - Use a user expression to set a global parameter's value?
>>     ex: define a parameter which refers to another one:
>>     {#PA("GPM_DHW")*500*65/1000000}
>>
>>     - Use a user expression in a parametric run component?
>>     Ex: I would like to set one keyword to refer to a global parameter
>>
>>
>>     - In parametric runs, reset values to be default values? Or at
>>     least specify the "unused" keyword?
>>
>>     Thanks,
>>     Julien
>>
>>     Side note: this is pretty weird, but if you have a UVT with HEAT
>>     SOURCE being electricity, it stills include some furnace losses,
>>     exactly 800 BTU/H (on your fuel meter) which is the DOE default.
>>     I found this because I've got one example where I have a UVT
>>     which Heat source is a furnace in my baseline, and it's actually
>>     electric in my proposed model.
>>     In my baseline, I have defined a user default for the FURNACE-AUX
>>     to be 0 BTU/H (no pilot light consumption). This 0 BTU/H value
>>     stays once I change heat source to electricity, and gives me a
>>     lower gas consumption that I would get if I manually restore
>>     FURNACE-AUX to be DOE default (which displays "n/a")).
>>
>>
>>
>>
>>     --
>>     Julien Marrec, EBCP, BPI MFBA
>>     Energy&Sustainability Engineer
>>     T: +33 6 95 14 42 13 <tel:%2B33%206%2095%2014%2042%2013>
>>
>>     LinkedIn (en) : www.linkedin.com/in/julienmarrec
>>     <http://www.linkedin.com/in/julienmarrec>
>>     LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr
>>     <http://www.linkedin.com/in/julienmarrec/fr>
>>
>>
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