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Exhaust fan in a return plenum - E+

asked 2017-05-02 12:41:02 -0500

Diego Lima's avatar

updated 2017-05-03 19:48:45 -0500

Hi all, I am trying to model a exhaust fan in a return plenum. When I detail the exhaust fan in the equipment list and connections E+ crashes, the message is that the return plenum is a controlled zone and cannot be used as a AirloopHVAC: ReturnPlenum. Did some of you do something similar to that ?

Thank you! Diego

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answered 2017-05-02 13:43:50 -0500

updated 2017-05-02 13:44:21 -0500

You are getting the error because a zone defined as a return plenum cannot also have ZoneHVAC equipment serving that zone. This restriction is mentioned in the I/O reference for AirLoopHVAC:ReturnPlenum field Zone Node Name:

Do not use the Zone Air Node Name specified in any ZoneHVAC:EquipmentConnections object, and since this zone is a plenum a ZoneHVAC:EquipmentConnections object is not required for the zone named in the previous field.

Here is a somewhat similar question regarding conditioning a plenum zone with radiant heaters. Their nominal solution was to separate the plenum into two zones.

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Hi Eric,

Thanks for your answer, understood. I was confused by a description in the same topic of the I/O Reference: AirLoopHVAC:ReturnPlenum "All the other attributes of a zone that can be specified in the building description can be used with a return plenum zone if necessary: scheduled loads, windows, etc." Now I got that building descritpion does not include HVAC equipment. Do you have some reference about how to separated the plenum into two zones?

Thanks again for your support. Diego

Diego Lima's avatar Diego Lima  ( 2017-05-02 14:09:09 -0500 )edit

Do you see some problem if I divide the real plenum in one zone with exhaust fans + a thin plenum at the top?

Diego Lima's avatar Diego Lima  ( 2017-05-04 14:43:46 -0500 )edit

Would it also work to hook up an "exhaust" fan (e.g. Fan:ConstantVolume/VariableVolume/OnOff instead of Fan:ZoneExhaust) to the relief node of the OutdoorAirMixer? Then you won't have to mess with zone geometry.

Eric Ringold's avatar Eric Ringold  ( 2017-05-04 14:53:24 -0500 )edit

The idea to add a fan in the relief node looks good, but I´m having problems on how to setup inlet/outlet nodes and how to control it. I started to work with E+ around 1 year ago and I´m not so experienced. I am researching some references on the documentation material but it´s not so easy to find. If you have some reference I would appreciate. Anyway, I thank you for the suggestions. -Diego

Diego Lima's avatar Diego Lima  ( 2017-05-05 09:53:05 -0500 )edit

FYI there are two EnergyPlus example files that have relief fans: 5ZoneAirCooledConvCoef.idf and 5ZoneAirCooledConvCoefPIU.idf, I recommend starting there.

Eric Ringold's avatar Eric Ringold  ( 2017-05-05 10:02:30 -0500 )edit

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Asked: 2017-05-02 12:41:02 -0500

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Last updated: May 02 '17