Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

water inlet-outlet node/IDF version error

asked 2016-04-01 10:27:23 -0600

elvin gravatar image

updated 2017-01-24 09:11:49 -0600

I'm modeling water to air heat pump in open studio but even though I can see the nodes in the loop tab, simulation gives error like following:

** Severe  ** IP: IDF line~121718 Error detected in Object=COIL:COOLING:WATERTOAIRHEATPUMP:EQUATIONFIT, name=WTR-TO-AIR HP CLG COIL 60
   **   ~~~   ** Field [Water Inlet Node Name] is required but was blank
   ************* IDF Context for following error/warning message:
   ************* Note -- lines truncated at 300 characters, if necessary...
   *************  121716 Coil:Cooling:WaterToAirHeatPump:EquationFit,
   ************* indicated Name=Wtr-to-Air HP Clg Coil 60
   ************* Only last 3 lines before error line shown.....
   *************  121717   Wtr-to-Air HP Clg Coil 60,            !- Name
   *************  121718   ,                                     !- Water Inlet Node Name
   *************  121719   ,                                     !- Water Outlet Node Name

Also I have a fatal error which is:

** Severe  ** IP: Possible incorrect IDD File
   **   ~~~   ** IDD Version:"IDD_Version 8.4.0"
   **   ~~~   ** Version in IDF="8.4" not the same as expected="8.4"
   **   ~~~   ** Possible Invalid Numerics or other problems
   **  Fatal  ** IP: Errors occurred on processing IDF file. Preceding condition(s) cause termination.

Has anyone encountered this type of error before?

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted

answered 2016-04-02 10:11:23 -0600

updated 2016-04-02 10:20:26 -0600

This error is saying that your water-to-air heat pump coils are not attached to a water loop.

To attach them to a water loop:

  1. Click on the water-to-air heat pump
  2. In the upper right corner, click on the Chain Link icon
  3. Check the box next to the name of the plant loop you want to connect the coil to. If you do not see any plant loop names, you'll need to add a plant loop to your model first (on the HVAC tab).
  4. Repeat for the heating and cooling coil (first two chain link icons). E+ uses two separate objects for the heating and cooling side of a heat pump, and they both need to be connected to a plant loop. Typically they are connected to the same plant loop. You'll notice that there are 3 chain link icons. The third is for the backup heating coil. This link only shows plant loops if the backup heating coil is hot water (no, this is not common, but E+ allows it).

See the second picture in this answer for a visual (for PTACs, but the process is the same).

edit flag offensive delete link more


@aparker what if you are modeling heat pumps at the city level (ie San Francisco Mid Rise Residential buildings from DOE)? How would I know which inlet and outlet node names to select?

helpneeder gravatar image helpneeder  ( 2019-08-19 17:41:46 -0600 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Training Workshops

Question Tools

1 follower


Asked: 2016-04-01 10:27:23 -0600

Seen: 595 times

Last updated: Jan 24 '17