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Maximum Outdoor Dry-Bulb Temperature for Supplemental Heater Operation

asked 2017-08-29 14:05:03 -0500

ptruong's avatar

updated 2017-08-29 16:06:38 -0500

Hello, My project has WSHP DOAS with a reheat coil. I am modeling this with unitary systems as suggested elsewhere on this forum. For one of the fields, "Maximum Outdoor Dry-Bulb Temperature for Supplemental Heater Operation", the value must be less than or equal to 21C.

I see how a max temp of 21C makes sense for a supplemental heating coil but not for a reheat coil. Is there a way to get this to work for a reheat coil?


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thank you, i didn't realize you could overwrite the default max in the idf without getting errors, but this seems to have worked.

ptruong's avatar ptruong  ( 2017-08-30 12:50:23 -0500 )edit

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answered 2017-08-29 15:24:18 -0500

You would need to enter a value for Max OAT for supplemental heater. If OS does not allow entry for that field then you will need to edit the idf and manually insert a value for that field. The default value is 21 C so I assume that field exists in the idf file. Export the file and search for AirloopHVAC:UnitarySystem to see what is available for edit. If there is not 40 fields then comma's will need to be added so you can enter your data.

This is from the IDD file. You will edit the idf file. This field is numeric field 18, but it is field 40 (N18+A22) in the list of inputs.

  N18, \field Maximum Outdoor Dry-Bulb Temperature for Supplemental Heater Operation
    \type real
    \units C
    \default 21.0
    \note Enter the maximum outdoor dry-bulb temperature for supplemental heater operation.
  A23, \field Outdoor Dry-Bulb Temperature Sensor Node Name
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Where is the input for this field in openstudio? I am currently modeling a supplemental heat coil for a PTHP baseline system. The supplemental heat coil is suppose to turn on below 40 degrees F, but I havent been able to find the input for the heat coil control.

hoffmann1320's avatar hoffmann1320  ( 2017-12-19 15:37:48 -0500 )edit

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Asked: 2017-08-29 14:05:03 -0500

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Last updated: Aug 29 '17