ideas on a workaround to override default control measures for water flow in Air Loop HVAC coils

asked 2016-01-20 13:13:14 -0500

TN's avatar

updated 2016-01-21 02:36:43 -0500

I am using the BCVTB to control E+ air loop simulations using building controllers.

The simulated air handlers all have water based heating and cooling coils delivering conditioned air via AirterminalSingleDuct:Uncontrolled, thus the supply air temperature from the fan outlet node has to be carefully controlled to produce nice simulation results. My physical controllers command the position of the heating and cooling valve, and I would very much like to use these outputs to set the desired portion of maximum mass flow rate to the coils when there is heating/cooling demand. For instance, ideally this would be accomplished through the use of SetpointManager:Scheduled in order to communicate the coil flow rate at any given time.

In other words, I have attempted to replace the Controller:WaterCoil objects in the AirLoopHVAC:ControllerList with setpoint managers in lieu of default controllers. I have found that this will not work because the list is specifically looking for a Controller:WaterCoil. I have investigated possible workarounds via EMS and UserDefined objects, but so far have found no evidence of a reliable workaround here.

I realize that the point of the Controller:WaterCoil is that E+ automatically sets the required flow based on management of the required AirLoop Supply Air Temperature. For this research, however, (due to the nature of the actual control logic), it would be desirable to control the water flow and report the SAT back to the controller. I could be wrong, but it seems EMS oriented control of water flow lends itself readily to plant control and not necessarily to control of water through Air Loop Coils.

In summary, my first choice would be to control the coil water flow, as it represents the actual control situation for this system. I already know that I can control the coils indirectly by sending in the desired SAT, only the logic of these particular controllers will have to be tweaked if this is indeed the only option.

Does anyone have any ideas on a workaround to override default control measures for water flow in Air Loop HVAC coils?







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This might be a little bit petty, but formatting your question a little better would help readability. Use code formatting using `, paragraphs (you have to let a blank line for markdown to start a new paragraph), and display images in your answer (you can still make them clickable). I'll edit your post to show you the difference it can make.

Julien Marrec's avatar Julien Marrec  ( 2016-01-21 02:33:20 -0500 )edit

Thank you Julien, I will be sure to format better next time. :)

TN's avatar TN  ( 2016-01-21 14:11:30 -0500 )edit

Did you try to use EMS to establish the setpoint at the sensor node used by the Controller:WaterCoil?

Archmage's avatar Archmage  ( 2016-01-22 10:16:38 -0500 )edit

Yes, thanks, I have tried this and can effectively establish the set-point of the sensor node. Because I am interfacing with an ExternalInterface I can actually do this just be defining the setpoint through SetPointManager:Scheduled and referencing a schedule that is specified by the external interface (which is really just a real controller signal). What I am hoping to accomplish is to actually just drive the coil flow and monitor temperature. Not sure if this will be possible, and if not, I will just resort to doing just that. This is artificial though, and it would be ideal to set the flow.

TN's avatar TN  ( 2016-01-22 12:22:45 -0500 )edit

The reason I think this is relevant to my current study is that the logic of the specific physical controller is designed to set either the hot or chilled water flow rate based on a calculated desired supply temperature.

TN's avatar TN  ( 2016-01-22 12:39:12 -0500 )edit