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Re: [EnergyPlus_Support] Coil:Cooling:DX:TwoSpeed and SHR



Ed, feel free to supply me with an input file so I can see where the low speed SHR as a problem with RH > 100%. I have just been making changes in that area and want all coil types to behave well.
rraustad@xxxxxxxxxxxx

On 6/30/2017 3:17 PM, 'Edward G. Lyon' eglyon@xxxxxxx [EnergyPlus_Support] wrote:

I am modeling an existing building with several roof top VAV systems.  I have system model numbers so I did not autosize any of the Coil:Cooling:DX:TwoSpeed system.  The SHR inputs for the model and error messages running the model make no sense to me:

 

Manufacturer data says SHR at low speed is much lower than at high speed (makes perfect sense to me), but E+ complains if the high speed and low speed SHR differ too much.

 

Using manufacturer data to calculate SHR inputs results in psychrometric calculation errors about RH exceeding 100%.  While the error message would suggest that more latent cooling is needed (lower SHR) the actual fix is to increase the SHR (less latent cooling).

 

So my model runs now runs without complaints with high speed SHR = low speed SHR = 0.77, not close to the manufacturer data. I would appreciate it if anyone could explain this E+ logic to me this.    

 

Ned Lyon, P.E. (MA, WV)
Staff Consultant

SIMPSON GUMPERTZ & HEGER 
     | Engineering of Structures and Building Enclosures

41 Seyon Street, Building 1, Suite 500
Waltham, MA 02453

781.907.9000 main
781.907.9350 direct 
617.285.2162 mobile 
781.907.9009 fax
www.sgh.com

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-- 
Richard Raustad
Florida Solar Energy Center
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Cocoa, FL 32922
Ph: (321)638-1454
http://www.fsec.ucf.edu/en/

Program Director
Electric Vehicle Transportation Center
http://evtc.fsec.ucf.edu/


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Posted by: Richard Raustad <rraustad@xxxxxxxxxxxx>


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