Fan power settings of parallel VAV Fan-powered boxes in E+

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appendix-g
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Hi Guys: Does any body know how to set "Maximum Primary Air Flow Rate" ,"Maximum Secondary Air Flow Rate" ,"Minimum Primary Air Flow Fraction" and "Fan On Flow Fraction" in energyplus to meet G3.1.3.14 "----" Fans in parallel VAV fan-powered boxes shall be sized for 50% of the peak design flow rate and shall be modeled with 0.74 W per L/s fan power. Minimum volume setpoints for fan-powered boxes shall be equal to 30% of peak design flow rate"？

hutiejun1223

asked 2014-10-30 04:58:01 -0500

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MatthewSteen

updated 2014-10-30 07:55:41 -0500

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Added "appendix-g" tag and changed G3.1.3.15 to G3.1.3.14 which corresponds to 90.1-2007, 2010, and 2013.

MatthewSteen (2014-10-30 07:55:24 -0500) edit

Note that the control of fan powered boxes according to PNNL 90.1 PRMRM guidance: 2010: https://www.pnnl.gov/main/publication... 2016: https://www.pnnl.gov/main/publication...

was fixed in E+ v8.7. https://github.com/NREL/EnergyPlus/pu...

DavidReddy (2018-05-08 14:09:17 -0500) edit

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For air flow it looks like you can set the air flow using the fields for these objects.

AirTerminal:SingleDuct:ParallelPIU:Reheat

AirTerminal:SingleDuct:SeriesPIU:Reheat

For fan power you can adjust the pressure rise to predict the W and W/L/s output from EnergyPlus. See the question below for resources.

Fan Power Inputs in OpenStudio

10.1k

MatthewSteen

answered 2014-10-30 08:05:31 -0500, updated 2014-10-30 08:31:17 -0500

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Hi! I set them as Autosize. Then I checked the results for "Maximum air flow" for every parallel box: I calculated 50% for every peak and I multiplied it for 0.74, therefore I obtained the power to set. Finally I used a simple proportion ("pressure input"/"power output Autosize simulation"="X"/"power calculated for G3.1.3.14") to obtain the right pressure rise to set for all the fans to get the power previously calculated. Using the equation is absolutely correct but if you don't change the efficiencies it should simply work with a proportion. I also set the fan percent to air flow to 0.