Unitary HP System on Supply Side

Thanks, Mingbo.

This definitely solved the issue. I also fixed the humidifier control.

The fluid issue still remains; despite me specifying the glychol, it has water as the medium. One thing I noticed is that I am actually trying to do a non-evaporative fluid cooler, which is in Open Studio but I guess is not in Ironbug yet. I do not know if this is a factor.

@Elliot_Glassman The reason that you cannot set its fluid type to Glycol is because there is a HotWaterBoiler in this loop’s supply side. I can set it successfully after I removed boiler from this loop.

I have added the non-evaporative fluid cooler in this update zip file. Please let me know if this works.
Ironbug_v0.0.12_20190707updates.zip (279.9 KB)

Hi Mingbo,

Thanks again for the quick response and update. Two questions:

  1. I get this error when I open up Grasshopper:


Does not seem to affect anything I have in my model however.

  1. This seems kind of weird, but is it possible that there is a value hard coded for the design flow rate? I left it blank so it would autosize, but the simulation keeps having a fatal error and the IDF error file implies an inputted design flow rate of 1.388000E-003 m3/s. When I input a higher value, it runs.

Hi @Elliot_Glassman,

  1. This version of Ironbug works with all versions (2.5, 2.8 or newer) of OpenStudio, but some updates are only available in OS2.8 or newer. These unfriendly exception messages will be removed in the next update.
  2. The design flow rate in which component?

Ah, I look forward to testing out 2.8 when I get through this exercise in 2.5!

The design flow rate in the fluid cooler. The error I get:

************* Beginning Plant Sizing Calculations
** Severe ** SizeFluidCooler: The combination of design input values did not allow the calculation of a
** ~~~ ** reasonable UA value. Review and revise design input values as appropriate. Specifying hard
** ~~~ ** sizes for some “autosizable” fields while autosizing other “autosizable” fields may be
** ~~~ ** contributing to this problem.
** ~~~ ** This model iterates on UA to find the heat transfer required to provide the design outlet
** ~~~ ** water temperature. Initially, the outlet water temperatures at high and low UA values are
** ~~~ ** calculated. The Design Exit Water Temperature should be between the outlet water
** ~~~ ** temperatures calculated at high and low UA values. If the Design Exit Water Temperature is
** ~~~ ** out of this range, the solution will not converge and UA will not be calculated.
** ~~~ ** The possible solutions could be to manually input adjusted water and/or air flow rates based
** ~~~ ** on the autosized values shown below or to adjust design fluid cooler air inlet dry-bulb temperature.
** ~~~ ** Plant:Sizing object inputs also influence these results (e.g. DeltaT and ExitTemp).
** ~~~ ** Inputs to the fluid cooler object:
** ~~~ ** Design Fluid Cooler Load [W] = 582060.00
** ~~~ ** Design Fluid Cooler Water Volume Flow Rate [m3/s] = 1.388000E-003
** ~~~ ** Design Fluid Cooler Air Volume Flow Rate [m3/s] = 139666.47
** ~~~ ** Design Fluid Cooler Air Inlet Dry-bulb Temp [C] = 35.00
** ~~~ ** Inputs to the plant sizing object:
** ~~~ ** Design Exit Water Temp [C] = 39.00
** ~~~ ** Loop Design Temperature Difference [C] = 11.00
** ~~~ ** Design Fluid Cooler Water Inlet Temp [C] = 51.67
** ~~~ ** Calculated water outlet temp at low UA [C] (UA = 58.21 W/K) = 51.50
** ~~~ ** Calculated water outlet temp at high UA [C] (UA = 582060.00 W/K) = 35.00

All the numbers are things I have input except for the Design Fluid Cooler Water Volume Flow Rate

@Elliot_Glassman , thanks for these details.
I wouldn’t be surprised that this is a bug from OpenStudio, as they had a similar issue before in CentralHeatPump.
I will do a quick test, and report it to OpenStudio team if needed.