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Two Setpoint Managers???

asked 2015-12-14 12:05:18 -0600

Dustin gravatar image

updated 2015-12-14 14:42:43 -0600

Hey all,

I am trying to get my simulation running and have been working through the errors. The error I am getting now is that I need to establish a setpoint at the humifier outlet node. This is the error.

* Severe * Humidifiers: Missing humidity setpoint for Humidifier:Steam:Electric = ELECTRIC HUMIDIFIER * ~~~ * use a Setpoint Manager with Control Variable = "MinimumHumidityRatio" to establish a setpoint at the humidifier outlet node.

So I understand I need to put a setpoint manager in but where can I place one in this model. I already have a setpoint manager for the temperature of the air leaving the entire unit. This air loop can be seen below.

image description

Edit: It should be noted that I cannot apply a setpoint manager humidity minimum because when I look in library the drop down menu is there but when I click it nothing shows up. image description

Edit: I can use a setpoint manager scheduled and change the control variable to Miniumum Humidity Ratio. Would the schedule then just be a fractional schedule?

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You should be able to see the SPM object under the "Library" list to drag and drop into your model. Once it's part of your model, then it may show up in the "My Model" list.

Aaron Boranian gravatar image Aaron Boranian  ( 2015-12-14 14:15:48 -0600 )edit

see my edit please. The setpoint manager is not even showing up.

Dustin gravatar image Dustin  ( 2015-12-14 14:34:26 -0600 )edit

Your schedule type for HumidityRatio control will be 'Dimensionless', not Fractional. This isn't well documented and I can't remember where I eventually found the requirement, I'll see if I can dig it up.

Eric Ringold gravatar image Eric Ringold  ( 2015-12-14 14:57:31 -0600 )edit

Thank you @Eric, I appreciate the response.

Dustin gravatar image Dustin  ( 2015-12-14 14:58:51 -0600 )edit

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answered 2015-12-14 12:14:49 -0600

pflaumingo gravatar image

updated 2015-12-14 22:49:43 -0600

@Dustin, you can place a sensor on any of the supply nodes above. So you could have a temperature set point manager on each node directly after your cooling/heating coil and a humidistat after the humidifier.

Update @Dustin, after seeing your updates the following should help with your set point manager issue for set points where the library doesn't have an object for you to drag. Open the model in the SketchUp Plugin and go to Window > Ruby Console. In the Ruby Console enter the following:

m = OpenStudio::Plugin.model_manager.model_interface.openstudio_model
node = m.getNodeByName("Node 42")
setPM = OpenStudio::Model::SetpointManagerSingleZoneHumidityMinimum.new(m)
setPM.addToNode(node)

Where "Node 42" is the node you want to place the set point manager. There is an issue with set point managers sometimes not showing up, but if you click on the node you should see that the set point manager information is there.

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Would this basically be the same thing that I described in my edit then? My understanding for my building is that they have a specific setpoint they want the humidity to be around, which is 27%. I understand that that may mean sending much lower or higher humidity supply air from the AHU. This is where I am getting confused as to what I should set the minimum humidity ratio leaving the unit as.

Dustin gravatar image Dustin  ( 2015-12-15 07:34:56 -0600 )edit

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Asked: 2015-12-14 12:05:18 -0600

Seen: 548 times

Last updated: Dec 14 '15