OS modulating LAT to reach setpoint

asked 2022-06-27 17:08:01 -0500

lowenergy's avatar

updated 2022-07-04 11:01:06 -0500

Hi, I've been using OS for about 6 months now... struggling with air loops. I'm using the generic Packaged Rooftop Unit with a single zone. I want the cooling coil to deliver 55F air and the heating coil (gas) to deliver 95F air and turn on/off as needed to reach setpoint with no modulation.

OS seems to be modulating the LAT off the coils to reach setpoint. I'm looking through the Eplusout results and can see how it's modulating the energy usage of the heating/cooling coil to increase/decrease the LAT off the coils.

How do I change this to only deliver 55F in cooling and 95F in heating. I feel like I've tried all of the setpoint managers and they don't seem to accomplish this. Am I missing something? I would appreciate any advise.

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A SetpointManager:Scheduled should provide exactly that though. Can you share your file or some plots and extracts?

Julien Marrec's avatar Julien Marrec  ( 2022-07-11 02:41:59 -0500 )edit

I don't have enough karma to upload any pictures, sorry about that. My understanding is the SetpointManager:Scheduled would require me to pick when the RTU is in heating mode and when it is in cooling mode. Meaning during shoulder season, if there is a call for heat but I have assigned cooling, the setpoint cannot be met. I would like the unit to decide which mode using automatic changeover logic and then deliver either 55F or 95F air accordingly to reach setpoint. Am I misunderstanding how the SetpointManger:Scheduled works?

lowenergy's avatar lowenergy  ( 2022-07-14 14:35:26 -0500 )edit

No, you're correct, that is how the SPM:Scheduled works. If you want to switch from 55F to 95F with it, you need to do some preprocessing and create a detailed schedule.

If you can identify a specific outside air temperature where it switches from heating to cooling, a SPM:OutdoorAirReset could work.

Otherwise I fear you're left with an EnergyManagementSystem solution, which requires using the bindings / writing a measure.

Julien Marrec's avatar Julien Marrec  ( 2022-07-16 05:36:47 -0500 )edit

Understood, thank you for the response!

lowenergy's avatar lowenergy  ( 2022-07-20 10:37:55 -0500 )edit