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Four pipe induction terminal: blank field in node definition

asked 2015-06-18 11:00:06 -0500

Elena Guidolin gravatar image

updated 2018-08-25 18:28:14 -0500

Dear all,

I am new with Openstudio. I am simulating a building conditioned by four pipe cooled beams. To do this I used HW CHW Four Pipe Induction Terminals. Modeling the system, I see that it works properly if I simulate a single zone with only one HW CHW Four Pipe Induction Terminal. If I do the same with more than one zone, it occours that the "Thermal Zone Exhaust Node List" has 2 nodes instead of one, as in my opinion it should be. Consequently these two fields are blank: " !- Induced Air Inlet Node Name" and " !- Air Inlet Node Name". If I go inside the IDF exported and I choose one of the two nodes and I fill these spaces it works properly.

This is the error I see running Openstudio: * Severe * IP: IDF line~31436 Error detected in Object=AIRTERMINAL:SINGLEDUCT:CONSTANTVOLUME:FOURPIPEINDUCTION, name=HW CHW FOUR PIPE INDUCTION TERMINAL 1 * ~~~ * Field [Induced Air Inlet Node Name] is required but was blank

This is the way that I fix it in EnergyPlus:

NodeList, Thermal Zone5-9 Exhaust Node List, !- Name !Node 238, !- Node Name 1
Node 214; !- Node Name 2

ZoneHVAC:AirDistributionUnit, HW CHW Four Pipe Induction Terminal 2 Air Distribution Unit, !- Name Node 210, !- Air Distribution Unit Outlet Node Name AirTerminal:SingleDuct:ConstantVolume:FourPipeInduction, !- Air Terminal Object Type HW CHW Four Pipe Induction Terminal 2; !- Air Terminal Name

AirTerminal:SingleDuct:ConstantVolume:FourPipeInduction, HW CHW Four Pipe Induction Terminal 2, !- Name , !- Availability Schedule Name Autosize, !- Maximum Total Air Flow Rate {m3/s} 2.5, !- Induction Ratio Node 213, !- Supply Air Inlet Node Name Node 214, !- Induced Air Inlet Node Name Node 210, !- Air Outlet Node Name , !- Hot Water Inlet Node Name , !- Cold Water Inlet Node Name Coil:Heating:Water, !- Heating Coil Object Type HW CHW Four Pipe Induction Terminal HW Htg Coil 2, !- Heating Coil Name , !- Maximum Hot Water Flow Rate {m3/s} 0, !- Minimum Hot Water Flow Rate {m3/s} 0.001, !- Heating Convergence Tolerance Coil:Cooling:Water, !- Cooling Coil Object Type HW CHW Four Pipe Induction Terminal CHW Clg Coil 2, !- Cooling Coil Name Autosize, !- Maximum Cold Water Flow Rate {m3/s} 0, !- Minimum Cold Water Flow Rate {m3/s} 0.001, !- Cooling Convergence Tolerance HW CHW Four Pipe Induction Terminal 2 Mixer; !- Zone Mixer Name

Coil:Heating:Water, HW CHW Four Pipe Induction Terminal HW Htg Coil 2, !- Name Always On Discrete 1, !- Availability Schedule Name Autosize, !- U-Factor Times Area Value {W/K} Autosize, !- Maximum Water Flow Rate {m3/s} Node 249, !- Water Inlet Node Name Node 250, !- Water Outlet Node Name Node 214, !- Air Inlet Node Name HW CHW Four Pipe Induction Terminal 2 Heating Coil Outlet, !- Air Outlet Node Name UFactorTimesAreaAndDesignWaterFlowRate, !- Performance Input Method Autosize, !- Rated Capacity {W} 82.2, !- Rated Inlet Water Temperature {C} 16.6, !- Rated Inlet Air Temperature {C} 71.1, !- Rated Outlet Water Temperature {C} 32.2, !- Rated Outlet Air Temperature {C} 0.5; !- Rated Ratio for Air and Water Convection

Anyone of u has an idea to fix this ... (more)

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Sounds like a bug, but I was not able to reproduce this. Would you mind giving a link to your model?

Kyle Benne gravatar image Kyle Benne  ( 2015-06-22 09:07:51 -0500 )edit
Elena Guidolin gravatar image Elena Guidolin  ( 2015-06-22 10:09:56 -0500 )edit

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answered 2015-06-28 23:13:52 -0500

updated 2016-10-28 13:09:43 -0500

I repaired your model by doing two things. First I removed three dangling zone exhaust nodes by manually editing the osm file. Second, I removed then re-added the terminals.

The repaired file is here.

I cannot say exactly why these dangling exhaust nodes ended up in your model. The API is supposed to prevent this kind of thing, but there have been past reports of it happening, and not necessarily related to the four pipe induction terminal, but always related to one of the terminal types that have induced air from the zone exhaust. I can say that after repairing your model I am able to remove the terminals cleanly, and add them back cleanly without issue in 1.7.0.

I sorted out the node connection issue related to your terminals in the above linked file, but I found other issues in your plant systems. Some of these may have been intentional on your part, but when I run the model I am seeing run away plant temperature. On your hot water plant I found a chiller which seems a little odd - I replaced the chiller with a boiler. The chiller I removed was connected to a condenser system - I removed this condenser system because it was left with no demand components. The chilled water condenser system had a ground hx on it - I replaced the ground heat exchanger with a cooling tower. The fully modified (and running) model is here.

I will keep an eye on this exhaust node issue. Please report back here if you have any more issues with that.

* Update on 10/28/2016 **

Here is an OpenStudio script I used to repair the model from Jesse Perreault. It might be helpful to other people.

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@Kyle Benne, I am having exactly the same problem with daggling exhaust nodes, this is before I split up the DOAS systems. I created a script to assign 4-pipe induction FCUs to thermal zones.... is there a quick way to fix this in OS? Thanks!

xfang gravatar image xfang  ( 2015-12-06 23:36:24 -0500 )edit

I am having exactly the same problem with exhaust nodes on four pipe induction units. Each efforts to remove and re-add zones/units within Openstudio results in yet another additional dangling exhaust node.
Wow, I can't figure out what to delete in the osm file since there doesn't appear to be an exhaust node list as in Eplus. If anyone has any advice on how to interpret I would be thankful.

jessep gravatar image jessep  ( 2016-10-24 16:16:00 -0500 )edit

I can take a look. Can you send your model to

Kyle Benne gravatar image Kyle Benne  ( 2016-10-26 09:46:38 -0500 )edit

@jessep I sent your repaired model back via email.

Kyle Benne gravatar image Kyle Benne  ( 2016-10-28 13:44:43 -0500 )edit

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Asked: 2015-06-18 11:00:06 -0500

Seen: 543 times

Last updated: Oct 28 '16