energyplus error when two vrf outdor units are identical

asked 2021-07-08 20:16:17 -0500

mattkoch gravatar image

updated 2021-07-09 07:32:38 -0500

I finally finished my Daikin VRV-IV epJSON library, well, as far as something like that can be finished anyway, so now I am exploring how well it works. This is a set of "Apply Now" measures for OpenStudio 2.9.1, and I do not know if the error I am describing in the following has been resolved since.

I have a test building with two floors and five zones per floor. The first floor zones are conditioned by a set of ZoneHVAC:TerminalUnit:VariableRefrigerantFlow (VRV-1-C, VRV-1-P-E, VRV-1-P-N, VRV-1-P-S, VRV-1-P-W) which are all connected to a single AirConditioner:VariableRefrigerantFlow (VRV-1-CU). The second floor zones are also conditioned by a set of ZoneHVAC:TerminalUnit:VariableRefrigerantFlow (VRV-2-C, VRV-2-P-E, VRV-2-P-N, VRV-2-P-S, VRV-2-P-W) which are all connected to a another single AirConditioner:VariableRefrigerantFlow (VRV-2-CU).

When the Daikin model for VRV-CU-1 is different from the Daikin model for VRV-2-CU, e.g. REYQ168XATJA vs. REYQ144XATJA, all is well, aside form still somewhat high unmet hours. However, when the two models are identical, that is VRV-1-CU and VRV-2-CU both are REYQ168XATJA, then I receive the following EnergyPlus error for each of the ten terminal units (shown below for VRV-1-C only):

* Severe * ZoneHVAC:TerminalUnit:VariableRefrigerantFlow "VRV-1-C (FXMQ36PBVJU)" * ~~~ * ...This terminal unit contains a heating coil and heating performance curves are also required in the associated condenser object. * ~~~ * ...Heating Capacity Ratio Modifier Function of Low Temperature Curve must also be specified for condenser = AirConditioner:VariableRefrigerantFlow "VRV-1-CU (REYQ168XATJA)". * Severe * ZoneHVAC:TerminalUnit:VariableRefrigerantFlow "VRV-1-C (FXMQ36PBVJU)" * ~~~ * ...This terminal unit contains a heating coil and heating performance curves are also required in the associated condenser object. * ~~~ * ...Heating Energy Input Ratio Modifier Function of Low Temperature Curve must also be specified for condenser = AirConditioner:VariableRefrigerantFlow "VRV-1-CU (REYQ168XATJA)".

I do not know whether if this was resolved, similar error messages would come up for the cooling curves. Obviously, I am only creating ONE set of curves to be shared by VRV-1-CU and VRV-2-CU when both are the same model. This seems to work for cooling, but not for heating. Is this misbehaving on EnergyPlus' part, or a misconception on mine?

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Comments

This error still occurs even after upgrading to OpenStudio 3.2.0 and EnergyPlus 9.4.

mattkoch gravatar image mattkoch  ( 2021-07-24 12:18:18 -0500 )edit