Re: [EnergyPlus_Support] The control problem

On Dec 18, 2013 4:50 PM, "Philip Haves" <phaves@xxxxxxx> wrote:

Dear Ying Yan,

I suggest comparing your IDF with one of the example files that include a boiler and a heating coil to see how to enable the boiler.

Phil

On 12/18/2013 1:25 PM, Yan, Ying wrote:
Dear Phil,
More information. As you said, I tried to check whether the boiler is shutting down. But I found that the boiler has no schedule item that can be used to control it, and I did not use the EMS to shut down the boiler. I do not know why the mass flow rate of the boiler is so low.

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Best Regards

Ying Yan

Graduate Student

Electrical & Computer Engineering

School of Engineering

University of Connecticut
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [EnergyPlus_Support@xxxxxxxxxxxxxxx] on behalf of Yan, Ying [yiy11005@xxxxxxxxxxxxxx]
Sent: Wednesday, December 18, 2013 4:17 PM
To: Philip Haves; EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] The control problem
Dear Phil,

Thank you so much for your help. I checked the outlet node of the boiler, the information is like

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BOILER OUTLET NODE:System Node Temperature [C](Hourly): 80 (correct)

BOILER OUTLET NODE:System Node Mass Flow Rate [kg/s](Hourly): 0.0010233 (seems the boiler is shutting down.)

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The information of the heating coil:

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FAU_1FLOOR SUPPLY SIDE INLET:System Node Temperature [C](Hourly): 13.00310 (This should be 80. Maybe it is because the boiler shuts down.)

FAU_1FLOOR SUPPLY SIDE INLET:System Node Mass Flow Rate [kg/s](Hourly): 0.554955 (This is strange since the boiler provides the hot water to several heating coil. The mass flow rate of the boiler should be greater than the mass flow rate of the heating coil. However, the opposite is true.)

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Can you give me some suggestions about this phenomenon? Thank you very much.

----------------------------------------

Best Regards

Ying Yan

Graduate Student

Electrical & Computer Engineering

School of Engineering

University of Connecticut
From: Philip Haves [phaves@xxxxxxx]
Sent: Wednesday, December 18, 2013 3:35 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Cc: Yan, Ying
Subject: Re: [EnergyPlus_Support] The control problem
Dear Ying Yan,

Check that you actually have water through the coil and through the boiler, using report variables for the actual flow. Then check that the boiler is enabled - it may be scheduled off.

Hope this helps,

Phil

On 12/18/2013 12:06 PM, Yan, Ying wrote:

Dear all,

I encountered a strange thing. I used a boiler to provide the hot water to the heating coil in the winter to ensure that the output air temperature should be 14 C. The setpoint of the boiler is that the output water should be 80 C. However, when I do the simulation, I got an error report as:

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** Severe ** FindRootSimpleController: Controller error for controller = "FAU_1FLOOR AHU HEATING COIL CONTROLLER"

** ~~~ ** Environment=ENNSMARTBUILDING, at Simulation time=12/15 00:00 - 00:30

** ~~~ ** Controller function is inconsistent with user specified controller action = "" action

** ~~~ ** Actuator will be set to maximum action

** ~~~ ** Controller control type=Temperature

** ~~~ ** Controller temperature setpoint = 14.00 [C]

** ~~~ ** Controller sensed temperature = 13.38 [C]

** ~~~ ** Controller actuator mass flow rate set to 1.39 [kg/s]

** ~~~ ** Controller actuator temperature = 11.71 [C]

** ~~~ ** Note: Chilled water coils should be reverse action and the entering chilled

** ~~~ ** water temperature (controller actuator temperature) should be below the setpoint temperature

** ~~~ ** Note: Hot water coils should be normal action and the entering hot

** ~~~ ** water temperature (controller actuator temperature) should be above the setpoint temperature

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You can see that the setpoint is 14 C, and the hot water temperature is just 11.71 C. Therefore, the air temperature cannot increase because the water temperature is lower than the air temperature. But it is strange because the water temperature should be 80 C since it comes from the boiler, rather than 11.71 C. I do not know why this thing happened. Can you give me some suggestions? Thank you.

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Best Regards

Ying Yan

Graduate Student

Electrical & Computer Engineering

School of Engineering

University of Connecticut
-- 
Philip Haves
Leader, Simulation Research Group 
Lawrence Berkeley National Laboratory
One Cyclotron Road, MS 90R3145
Berkeley, CA 94720-8134
(510) 486 6512 (office)
(510) 486 4089 (fax)