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Water node mass flow rate in EMS

asked 2020-06-13 09:47:30 -0500

Aly ElHefny's avatar

updated 2020-06-14 19:09:04 -0500

Hello everyone, hope you are all in good health. I've been trying to work with water heater use side mass flow rate but had no luck. I have a simple WaterHeaterMixed. When using sensor in EMS, WATER HEATER_UNIT1,Water Use Equipment Hot Water Mass Flow Rate or node mass flow rate. I get an error of invalid output:variable. I've also tried with the following related nodes and still get the same outcome:

  • DHW Supply Outlet Node_unit1
  • DHW Demand Inlet Node_unit1
  • Mains Inlet Node_unit1
  • Mains Makeup Node_unit1


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Thanks !

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Does this post or this post answer your question?

Aaron Boranian's avatar Aaron Boranian  ( 2020-06-13 14:39:48 -0500 )edit

Hello Aaron, thanks for your reply. I believe I've already followed the info in those two posts but still with no luck. The sensor is set using the name found in RDD file and I believe the name is complete as shown.

Aly ElHefny's avatar Aly ElHefny  ( 2020-06-13 14:50:45 -0500 )edit

Could you update your post to include the text of your EMS sensor object and full text of the error message? You likely have an input field in the wrong location.

Aaron Boranian's avatar Aaron Boranian  ( 2020-06-13 15:31:20 -0500 )edit

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answered 2020-06-15 08:30:53 -0500

There is a typo in the third input field for Output:Variable or Output:Meter Name. The WaterHeater:Mixed object type represents a water heater that provides hot water. From its list of output variables, it looks like you want to use Water Heater Use Side Mass Flow Rate. The severe error you are seeing is because the Water Use Equipment Hot Water Mass Flow Rate output variable that you tried to assign is actually for a different object type -- WaterUse:Equipment, which is used to define individual components that use hot water (showers, sinks, etc.).

As mentioned in the two posts I linked to in my comment above, the third input field of the EMS sensor should match with a viable output variable or meter that you can find in the report data dictionary (RDD) output file generated by EnergyPlus after each simulation. One downside of the RDD file, however, is that it only gives you variable names without the object type that is generating each output variable. If you want to confirm that information, then you should read through the Input Output Reference documentation. Each object type has it's Input fields described, as well as each Output variable the object type can generate -- hence the name Input Output Reference.

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Asked: 2020-06-13 09:47:30 -0500

Seen: 104 times

Last updated: Jun 15 '20