Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
The combination ratio curve is used to calculate a multiplier when the installed total indoor unit capacity is greater than the outdoor unit capacity. If the installed indoor unit capacity is less than or equal to the outdoor unit capacity, a combination curve is not required and the assumed multiplier is 1. EMS cannot be used to adjust this performance curve result. It's usefulness come when you decide to add another indoor terminal unit a perform a different simulation. If the new indoor unit capacity is greater than the outdoor unit capacity, the multiplier is automatically calculated for you.
2.1. Yes, the VRF coil model is different from the typical DX coil and actually requires fewer inputs. 2.2. No, the performance curves for the new VRF model in V8.4 does not use the capacity and energy input ratio performance curves. It is instead a component model that relies more on physics to determine performance. Do not use the old curves.
| | 2 | No.2 Revision |
The combination ratio curve is used to calculate a multiplier when the installed total indoor unit capacity is greater than the outdoor unit capacity. If the installed indoor unit capacity is less than or equal to the outdoor unit capacity, a combination curve is not required and the assumed multiplier is 1. EMS cannot be used to adjust this performance curve result. It's usefulness come when you decide to add another indoor terminal unit a perform a different simulation. If the new indoor unit capacity is greater than the outdoor unit capacity, the multiplier is automatically calculated for you.
2.1. Yes, the VRF coil model is different from the typical DX coil and actually requires fewer inputs.
inputs.
2.2. No, the performance curves for the new VRF model in V8.4 does not use the capacity and energy input ratio performance curves. It is instead a component model that relies more on physics to determine performance. Do not use the old curves.
| | 3 | No.3 Revision |
.1. The combination ratio curve is used to calculate a multiplier when the installed total indoor unit capacity is greater than the outdoor unit capacity. If the installed indoor unit capacity is less than or equal to the outdoor unit capacity, a combination curve is not required and the assumed multiplier is 1. EMS cannot be used to adjust this performance curve result. It's usefulness come when you decide to add another indoor terminal unit a perform a different simulation. If the new indoor unit capacity is greater than the outdoor unit capacity, the multiplier is automatically calculated for you.
.2.
As this document explains, only 1 Cooling Capacity/Energy Ratio Function of Temperatures curve is all that is required. However, most if not all VRF systems have very distinctly different performance at low and high outdoor temperatures. Thus users will typically model the VRF system using 2 performance curves. The boundary curve tells the program which performance curve to use based on outdoor and indoor temperatures.2.1. Yes, the VRF coil model is different from the typical DX coil and actually requires fewer inputs.
2.2. No, the performance curves for the new VRF model in V8.4 does not use the capacity and energy input ratio performance curves. It is instead a component model that relies more on physics to determine performance. Do not use the old curves.
| | 4 | No.4 Revision |
.1.
.2.
2.1.
| | 5 | No.5 Revision |
The combination ratio curve is used to calculate a multiplier when the installed total indoor unit capacity is greater than the outdoor unit capacity. If the installed indoor unit capacity is less than or equal to the outdoor unit capacity, a combination curve is not required and the assumed multiplier is 1. EMS cannot be used to adjust this performance curve result. It's usefulness come comes when you decide to add another indoor terminal unit a and perform a different simulation. If the new indoor unit capacity is greater than the outdoor unit capacity, the multiplier is automatically calculated for you.
As this document explains, only 1 Cooling Capacity/Energy Ratio Function of Temperatures curve is all that is required. However, most if not all VRF systems have very distinctly different performance at low and high outdoor temperatures. Thus users will typically model the VRF system using 2 performance curves. The boundary curve tells the program which performance curve to use based on outdoor and indoor temperatures.
Yes, the VRF coil model is different from the typical DX coil and actually requires fewer inputs.
No, the performance curves for the new VRF model in V8.4 does not use the capacity and energy input ratio performance curves. It is instead a component model that relies more on physics to determine performance. Do not use the old curves.
