This field defines the total cooling capacity (sensible + latent) of the heat pump at rated conditions in W or Btu/h. The cooling capacity must be greater than 0 or set to autosize.
When the VRF outdoor unit is not autosized, the sum of the VRF terminal unit coils (autosized or not) and the VRF outdoor unit capacity are used to calculate the combination ratio for both cooling and heating. For a fully autosized system, the combination ratio = 1, but when the system is not fully autosized, the resulting sizes of the terminal unit coils and the outdoor unit are used to calculate a combination ratio.
This field defines the cooling coefficient of performance at rated conditions. The cooling coefficient of performance includes compressor power and condenser fan power. This COP value does not include impacts due to the supply air fan.
This field defines the minimum outdoor dry-bulb temperature allowed for cooling operation (in °C or °F). Below this temperature, cooling is disabled.
This field defines the maximum outdoor dry-bulb temperature allowed for cooling operation (in °C or °F). Above this temperature, cooling is disabled.
The way that the cooling capacity ratio modifier varies with temperature can be defined using either a single curve (if the cooling capacity does not change dramatically with changes in outdoor conditions) or by using multiple (3) curves if the trend in cooling capacity changes dramatically as outdoor temperature changes. Select from:
Available only when using a single cooling capacity ratio modifier function of temperature curve, this field defines the cooling capacity ratio modifier at all outdoor dry-bulb temperatures. This curve is a bi-quadratic equation using weighted average indoor wet-bulb temperature (i.e., the indoor terminal units weighted average inlet temperatures) and condenser entering air dry-bulb temperature as the independent variables.
Available only when using multiple cooling capacity ratio modifier function of temperature curves this field defines the cooling capacity ratio modifier at low outdoor dry-bulb temperatures. This curve is a bi-quadratic equation using weighted average indoor wet-bulb temperature (i.e., the indoor terminal units weighted average inlet temperatures) and condenser entering air dry-bulb temperature as the independent variables.
Available only when using multiple cooling capacity ratio modifier function of temperature curves, this curve defines the cooling capacity ratio boundary. It is a linear, quadratic or cubic curve that defines a change in cooling capacity at a specific condenser entering air dry-bulb temperature as a function of indoor air wet-bulb temperature.
Available only when using multiple cooling capacity ratio modifier function of temperature curves, this field defines the cooling capacity ratio modifier at high outdoor temperatures. This curve is a bi-quadratic equation using weighted average indoor wet-bulb temperature and condenser entering air dry-bulb temperature as the independent variables.
The Cooling energy input ratio (EIR) modifier is a factor used to adjust the rated EIR (reciprocal of Rated cooling COP) as outdoor temperature changes.
The way that the cooling EIR varies with temperature can be defined using either a single curve (if the cooling EIR does not change dramatically with changes in outdoor conditions) or by using multiple (3) curves if the trend in cooling EIR changes dramatically as outdoor temperature changes. Select from:
Available only when using a single cooling capacity ratio modifier function of temperature curve, this field defines the cooling energy input ratio modifier at all outdoor temperatures. This curve is a bi-quadratic equation with a weighted average indoor wet-bulb temperature and condenser entering air dry-bulb temperature as the independent variables.
Available only when using multiple cooling EIR curves, this field defines the cooling energy input ratio modifier at low outdoor temperatures. This curve is a bi-quadratic equation with a weighted average indoor wet-bulb temperature and condenser entering air dry-bulb temperature as the independent variables.
Available only when using multiple cooling EIR curves, the cooling energy input ratio boundary curve is a linear, quadratic or cubic curve that defines a change in cooling energy at a specific condenser entering air dry-bulb temperature as a function of indoor air wet-bulb temperature.
Available only when using multiple cooling EIR curves, this field defines the cooling energy input ratio modifier at high outdoor temperatures. This curve is a bi-quadratic equation with weighted average indoor wet-bulb temperature and condenser entering air dry-bulb temperature as the independent variables.
This curve defines how the cooling EIR modifier varies as a function of part-load ratio when PLR is less than or equal to 1. It is a linear, quadratic or cubic equation with cooling part-load ratio used as the independent variable. The cooling energy input ratio modifier curve is normalized to 1 at a part-load ratio of 1 and is used only when the operating part-load ratio is less than or equal to 1.
This curve defines how the cooling EIR modifier varies as a function of part-load ratio when PLR is greater than 1. It is a linear, quadratic or cubic equation with cooling part-load ratio used as the independent variable. The cooling energy input ratio modifier curve is normalized to 1 at a part-load ratio of 1 and is used only when the operating part-load ratio is greater than 1.
This field defines the cooling combination ratio (CR) correction factor curve for combination ratios greater than or equal to 1. The combination ratio is defined as the total rated indoor terminal unit cooling capacity divided by this heat pump’s Rated total cooling capacity. The curve is a linear, quadratic or cubic equation and uses the minimum value of x in the curve object to determine the maximum part-load ratio which is linearly proportional to capacity (i.e., the minimum value of x [CR] in the curve object must be ≥1). The output of this curve provides a multiplier (>1) which is applied to this heat pump’s Rated total cooling capacity. Between a combination ratio of 1 and the curve’s minimum value of x, the multiplier is linearly interpolated. For combination ratio’s less than 1 (i.e., the total indoor terminal unit capacity is less than this heat pump’s rated total capacity), capacity is directly proportional to part-load ratio and this curve will not be used.
This field defines the cooling part-load fraction correlation curve. This curve is used to define the cycling losses when the condenser’s compressors cycle on and off. The compressor cycles when the cooling part-load ratio is less than the Minimum heat pump part-load ratio.