OS 2.5: PlantEquipmentOperationSchemes: missing property

I have simple water loop as follows:

image description

It contains the tank of an air-to-water heatpump water heater attached to a zone, and a hot water user.

When running the osm model, the simulation crashes with the following err messages:

Program Version,EnergyPlus, Version 8.9.0-eba93e8e1b, YMD=2018.06.20 10:13,
   ** Severe  ** <root>[PlantEquipmentOperationSchemes][HotWaterLoop Operation Schemes] - Missing required property 'control_scheme_1_name'.
   ** Severe  ** <root>[PlantEquipmentOperationSchemes][HotWaterLoop Operation Schemes] - Missing required property 'control_scheme_1_object_type'.
   ** Severe  ** <root>[PlantEquipmentOperationSchemes][HotWaterLoop Operation Schemes] - Missing required property 'control_scheme_1_schedule_name'.
   **  Fatal  ** Errors occurred on processing input file. Preceding condition(s) cause termination.
   ...Summary of Errors that led to program termination:
   ..... Reference severe error count=3
   ..... Last severe error=<root>[PlantEquipmentOperationSchemes][HotWaterLoop Operation Schemes] - Missing required property 'control_scheme_1_schedule_name'.
   ************* Warning:  Node connection errors not checked - most system input has not been read (see previous warning).
   ************* Fatal error -- final processing.  Program exited before simulations began.  See previous error messages.
   ************* EnergyPlus Warmup Error Summary. During Warmup: 0 Warning; 0 Severe Errors.
   ************* EnergyPlus Sizing Error Summary. During Sizing: 0 Warning; 0 Severe Errors.
   ************* EnergyPlus Terminated--Fatal Error Detected. 0 Warning; 3 Severe Errors; Elapsed Time=00hr 00min  0.17sec

Apparently, OpenStudio has generated an incomplete IDF file. Did I miss anything necessary to specify ?

2.3k

OS-user-AT

asked 2018-06-20 06:08:56 -0500

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Can you share your OSM file?

Julien Marrec (2018-06-20 06:40:34 -0500) edit

Bien Sur ! To which email address should I send it, or can I directly upload it to unmethours ? (relatively small file)

OS-user-AT (2018-06-20 11:31:14 -0500) edit

You can host the file anywhere you see fit (google drive, dropbox, wetransfer, or event gist or similar code-sharing platforms since OSM=text file after all) and include a link in your original question.

Julien Marrec (2018-06-20 18:04:48 -0500) edit

here is the time-limited download link:

OS-user-AT (2018-06-21 01:28:26 -0500) edit

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1 Answer

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The problem is that the HPWH isn't recognized as a Heating component, and when OpenStudio defaults the PlantEquipmentOperationScheme for your plantLoop since you didn't explicitly create one, it finds nothing to put on it.

This can be seen by looking at the "Control" tab of the Hot Water Loop, you see it's empty:

NoHeat

This happens because your WaterHeater:Mixed Maximum Heater Capacity is hardsized to 0:

Zero Cap

Workarounds

Anyways, you can either:

Input a non zero-capacity in the WaterHeater:Mixed (even if extremely small, say 1 BTU/h), which is the easiest.
Create an explicit PlantEquipmentOperation:HeatingLoad and assign the WaterHeater:HeatPump (not the WaterHeater:Mixed) as equipment and set that to the HW Loop. You must use the (ruby) API for this.

Here's the control tab with a 1 BTU/h capacity:

image description

In both cases, your file will still crash in E+, but due to a completely different problem that has nothing to do on this thread.

** Severe  ** CalcHeatBalanceInsideSurf: The temperature of -19623.88 C for zone="DATACENTER", for surface="ZN001:WALL003"
**   ~~~   ** ..is very far out of bounds during warmup. This may be an indication of a malformed zone.

Context/More Info

The portion of source code that does this is in ForwardTranslatePlantEquipmentOperationSchemes.cpp#L418:L435.

I'm probably to blame here since I'm the one that modified this portion to perform a check - as opposed to the old way which was to always assume ComponentType::HEATING - to try to determine the true type of a WH:Mixed, which can be used as a Buffer+HX between loops that may be for cooling for eg. I didn't foresee the HPWH case, and I'm not too familiar with this object and the example files always have a capacity for the associated WaterHeater:Mixed/Stratified, but I guess that's probably just the electric/gas backup inside the tank, in which case I'd consider this a bug to fix so I opened issue#3164.