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Problem with fancoil modeling [closed]

asked 2016-04-06 05:40:17 -0500

FSilenzi gravatar image

updated 2016-04-07 15:44:34 -0500

I have consulted the InputOutput guide and the "search" function but with poor results about how to model a cooling only fancoil in openstudio. At the moment I am using a simple air loop with a cooling coil and a fan, with a single duct uncontrolled diffuser. The setpoint is a simple scheduled setpoint manager. See the image below for more clarity.

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I wonder if this configuration can be used to mimick a cooling only fancoil. The major incongruence is that the fancoil recirculates and cools the indoor air (the ach are assured with a VAV system) while with this configuration it will take fresh air from outdoor. I have also tryed to use a 4pipes fancoil, but apparently I cannot place it anywhere in my loop (both demand or supply side nodes). I have read that the 4 pipes configuration can be used to simulate a 2pipes configuration, setting the availability schedules accordingly. I have also tryed to simulate without the outdoor air intake, but the simulation fails with the following error:


Thanks to anyone that will contribute


edit: I have set the coil detail as follow

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but I encounter error

The design coil load is zero for Coil:Heating:Water FAN COIL WITH VAR FAN CONST FLUID FLOW - HEATING COIL * ~~~ * An autosize value for UA cannot be calculated * ~~~ * Input a value for UA, change the heating design day, or raise * ~~~ * the zone heating design supply air temperature

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Closed for the following reason the question is answered, right answer was accepted by FSilenzi
close date 2019-03-08 06:47:04.118888

1 Answer

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answered 2016-04-06 06:43:31 -0500

updated 2016-04-06 08:41:42 -0500

Use a 4-pipe fan coil. This is a ZoneHVAC component and as such should be attributed the thermal zone, not an airloop.

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Then set the heating coil availability schedule to be always 0 to ensure it stays off.

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You'll notice one thing though: the library four pipe fan coils have water heating coils, which requires you to hook it to a plant loop. If you already have a heating plant loop, put it there. It won't do anything because it's off.

Here's how to hook it up to a plant loop:

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BUT, if you are familiar with the OpenStudio API, I strongly suggest building your own fan coil using an Electric heating coil instead...

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Thanks @Julien Marrec I have followed you advice and my simulation went smooth. What is strange is that I dont have "Always Off" schedule into the list. I have a lot of "Always On" and a black space, I have selected the blank space. Also I have checked the air inlet and outlet node name, but I cannot find these nodes into my plant scheme. Do the system take air from outside or it connected itself in order to not intake any outdoor air?

edit: I am not familiar with writing measures and I have few time to dedicate learning this feature, so I believe that working with OS API isn't viable.

FSilenzi gravatar image FSilenzi  ( 2016-04-06 07:33:39 -0500 )edit

You can create own "Always Off" schedule, just copy "Always On" and convert to "Always OFF." They are simple schedules with 0 and 1. Fan Coils are zone level equipment so the inlet air node should be air inlet node for that specific zone. Hope this helps.

BL gravatar image BL  ( 2016-04-06 07:52:46 -0500 )edit

@FSilenzi: I added a picture to show how to hook the coils to the plant loop.

You seem to be confused between Plant Loop, AirLoop and ZoneHVAC components (and their nodes), aren't you?

Julien Marrec gravatar image Julien Marrec  ( 2016-04-06 08:43:05 -0500 )edit

Thanks @Bo_Lin and @Julien Marrec I am familiar with basic standard openstudio library objects, but I am still pretty new to other kinds (i.e. radiators and fancoils) so any help is welcome. For the hooking process I figured out how to do it resorting to the search function, after having defined the new "Always off" new schedule to prevent the heating coil from work. To be sure that no heating is delivered I will check the ResultViewer, it should not contain any heating variable related to the fancoil, right? Or is there another way to figure it out?

FSilenzi gravatar image FSilenzi  ( 2016-04-06 09:07:08 -0500 )edit

The result viewer won't have any variables about the fan coil unless you tell it to report them. Unfortunately you won't be able to select for example HVAC,Sum,Fan Coil Heating Energy [J] directly in the OS App. Unless you want to use a measure, you can get the out.idf in run\4-EnergyPlusPreProcess-0, add the output variable there, and run it for a winter day and then check the results viewer

Julien Marrec gravatar image Julien Marrec  ( 2016-04-06 09:41:13 -0500 )edit


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Asked: 2016-04-06 05:40:17 -0500

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Last updated: Apr 07 '16