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ZoneHVAC:FourPipeFanCoil Night Cycle Control?

asked 2014-12-15 18:21:52 -0500

jdunn's avatar

updated 2018-08-25 18:28:41 -0500

Hello all -

I'm modeling zonal fan coil units (constant fan, variable flow) with a dedicated outside air system, and I was wondering if there is any way to get night cycle control?

I'm using the template objects, and there is no field for night cycle control. I can swap out the availabilitymanager:scheduled for an availabilitymanager:nightcycle in the DOAS airloop post-expansion, but it doesn't work.

I've also noticed that there is an additional field in the ZoneHVAC:FourPipeFanCoil that isn't typically there. It is a field that asks for an availability manager list. However, upon creating a list with the appropriate night cycle manager, still nothing. I thought maybe it was because it was using a fan:constantvolume and not a fan:onoff, but that didn't work either.

Is it possible, and if so, how? Thanks for your time and help!

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answered 2014-12-17 10:07:50 -0500

As an idea, did you put the correct schedule on your fans. For example, are they always on or did you put a schedule so they are off at night? The night cycle manager needs them to be off so it can turn them on if needed. You will need to put the availability manager on the fan coil object (if you open the .expidf file you will see that object expanded out from the templates. If you want the night cycle manager on the DOAS system you will need to put the availability manager on the airloopHVAC piece.

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Annie, thanks for the info!

I indeed had a schedule that included "0's" during unoccupied times. I was editing the expanded .idf, and I'm fairly certain everything had the right schedule, but I'll double check. I also did add the availability manager to the expanded object from the template (in the optional field in the ZoneHVAC:FourPipeFanCoil" expanded object) and still nothing.

When reading the documentation in the inputoutputreference, it sounds like the nightcycle manager was designed for "central air systems," so I'm wondering if it will work with the fancoil object at all.

jdunn's avatar jdunn  ( 2014-12-17 13:21:17 -0500 )edit

I think you might be right, we haven't used it on zone equipment before. I would imagine, if you are using an on off fan the fan coil will turn off automatically if conditioning isn't required with no need for night cycle control. The zone components usually don't require too much outside input to make them work correctly. If you report out your node temperatures and flow rates and look at your ESO file you can see if the fan coil is turning off when conditioning isn't required.

Annie Marston's avatar Annie Marston  ( 2014-12-17 14:01:16 -0500 )edit

Availability managers were originally designed for air loops and then plant loops, but they were extended to work with zone equipment as well (even if the documentation implies otherwise). Check the availability schedules for the fancoil object itself and its coils. These all need to be on at all times. The night cycle manager only overrides the schedule on the fan object. If that doesn't solve it, please post your idf file or send it to the EnergyPlus helpdesk at

MJWitte's avatar MJWitte  ( 2014-12-18 16:13:30 -0500 )edit

Michael - Fantastic information! I was definitely applying an on/off schedule to all of the components in the fancoil system. However, upon revisiting and ensuring that the fancoil, heating coil, and cooling coil all have always-on schedules --- and ensuring the fan object and availability manager's fan schedule field have the on/off schedules---- still no cycling at night. Here is a link to the .idf with only those objects included in case you want to take a look.

jdunn's avatar jdunn  ( 2014-12-18 17:50:53 -0500 )edit

It looks correct, but since it's just a snippet, I can't run it to try things out. Two suggestions, report the output variable Fan Coil Availability Status to see if the manager it is really asking the fan coil to turn on (the status codes are explained in the I/O Ref under fan coil outputs). Second, just for kicks, try setting the night cycle manager to CycleOnAnyZoneFansOnly. That shouldn't be necessary, but would be interesting to see if it makes a difference.

MJWitte's avatar MJWitte  ( 2014-12-18 19:39:25 -0500 )edit

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Asked: 2014-12-15 18:21:52 -0500

Seen: 322 times

Last updated: Dec 17 '14