This numeric field defines the total heat pump heating capacity at rated conditions in watts. The nominal heat pump heating capacity must be greater than 0 or set to autosize.
This field defines the ratio of heating to cooling capacity of the Outdoor unit. This value must be greater than or equal to 1. A similar input is available in the VRF indoor unit.
When the outdoor unit Rated total heating capacity (above) is autosized this ratio is used to scale the heating capacity of the outdoor unit to the Rated total cooling capacity of the outdoor unit regardless of the capacities of the DX heating coils in the indoor units.
The zone indoor units heating coils are also sized using this ratio unless they are hard-sized in the indoor unit.
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 heating coefficient of performance at rated conditions. The heating coefficient of performance includes compressor power and condenser fan power. This COP value does not include impacts due to the supply air fan. The nominal heat pump heating COP must be greater than 0.
This field defines the minimum outdoor temperature allowed for heating operation. Below this temperature, heating is disabled. If this field is left blank, the default value is -20ºC.
This field defines the maximum outdoor temperature allowed for heating operation. Above this temperature, heating is disabled. If this field is left blank, the default value is 16ºC.
This choice field defines the outdoor temperature type used for all performance curves. The valid choices are:
The default value is 1-Wet-bulb temperature. Manufacturers will typically provide heating performance data as a function of outdoor air wet-bulb temperatures. This means that the performance (e.g., capacity and energy input ratio) curves will use outdoor wet-bulb temperature as one of the independent variables. At times, manufacturers will only provide performance data as a function of outdoor dry-bulb temperatures. In this case, all performance curves shall be developed using outdoor dry-bulb temperature and this field shall be selected as 2-Dry-bulb temperature.
The way that the heating capacity ratio modifier varies with temperature can be defined using either a single curve (if the heating capacity does not change dramatically with changes in outdoor conditions) or by using multiple (3) curves if the trend in heating capacity changes dramatically as outdoor temperature changes. Select from:
Available only when using single heating capacity ratio modifier function of temperature curve, this curve defines the heating capacity ratio modifier at all outdoor temperatures. It is a bi-quadratic equation with a weighted average indoor dry-bulb temperature (i.e., the indoor terminal units weighted average inlet temperatures) and condenser entering air dry-bulb or wet-bulb temperature as the independent variables. Since manufacturers may provide performance data using either outdoor dry-bulb or wet-bulb temperatures, either of these temperature types may be used for heating performance curves as specified in Heating performance curve outdoor temperature type.
Available only when using multiple heating capacity ratio modifier function of temperature curves this field defines the heating capacity ratio modifier at low outdoor temperatures. This curve is a bi-quadratic equation with a weighted average indoor dry-bulb temperature (i.e., the indoor terminal units weighted average inlet temperatures) and condenser entering air dry-bulb or wet-bulb temperature as the independent variables. Since manufacturers may provide performance data using either outdoor dry-bulb or wet-bulb temperatures, either of these temperature types may be used for heating performance curves as specified in Heating performance curve outdoor temperature type.
Available only when using multiple heating capacity ratio modifier function of temperature curves, this curve defines the heating capacity ratio boundary. It is a quadratic or cubic curve that defines a change in heating capacity at a specific condenser entering air dry-bulb or wet-bulb temperature as a function of indoor air dry-bulb temperature. Since manufacturers may provide performance data using either outdoor dry-bulb or wet-bulb temperatures, either of these temperature types may be used for heating performance curves as specified in Heating performance curve outdoor temperature type.
Available only when using multiple heating capacity ratio modifier function of temperature curves, this curve defines the heating capacity ratio modifier at high outdoor temperatures. It is a bi-quadratic equation with a weighted average indoor dry-bulb temperature and condenser entering air dry-bulb or wet-bulb temperature as the independent variables. Since manufacturers may provide performance data using either outdoor dry-bulb or wet-bulb temperatures, either of these temperature types may be used for heating performance curves as specified in Heating performance curve outdoor temperature type.
The heating energy input ratio (EIR) modifier is a factor used to adjust the rated EIR (reciprocal of Rated heating COP) as outdoor temperature changes.
The way that the heating EIR varies with temperature can be defined using either a single curve (if the heating EIR does not change dramatically with changes in outdoor conditions) or by using multiple (3) curves if the trend in heating EIR changes dramatically as outdoor temperature changes. Select from:
Available only when using a single heating EIR curve, this curve defines the heating EIR modifier at all outdoor temperatures. It is a bi-quadratic equation with a weighted average indoor dry-bulb temperature and condenser entering air dry-bulb or wet-bulb temperature as the independent variables. Since manufacturers may provide performance data using either outdoor dry-bulb or wet-bulb temperatures, either of these temperature types may be used for heating performance curves as specified by Heating performance curve outdoor temperature type.
Available only when using multiple heating EIR curves, this curve defines the heating EIR modifier at low outdoor temperatures. It is a bi-quadratic equation with a weighted average indoor dry-bulb temperature and condenser entering air dry-bulb or wet-bulb temperature as the independent variables. Since manufacturers may provide performance data using either outdoor dry-bulb or wet-bulb temperatures, either of these temperature types may be used for heating performance curves as specified by Heating performance curve outdoor temperature type.
Available only when using multiple heating EIR curves, the heating EIR boundary curve is a quadratic or cubic equation that defines a change in heating energy at a specific condenser entering air dry-bulb or wet-bulb temperature as a function of indoor air wet-bulb temperature. Since manufacturers may provide performance data using either outdoor dry-bulb or wet-bulb temperatures, either of these temperature types may be used for heating performance curves as specified by Heating performance curve outdoor temperature type.
Available only when using multiple heating EIR curves, the heating EIR modifier at high temperature curve is a bi-quadratic equation with a weighted average indoor dry-bulb temperature and condenser entering air dry-bulb or wet-bulb temperature as the independent variables. Since manufacturers may provide performance data using either outdoor dry-bulb or wet-bulb temperatures, either of these temperature types may be used for heating performance curves as specified by Heating performance curve outdoor temperature type.
This curve defines how the heating energy input ratio (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 heating part-load ratio used as the independent variable. The heating energy input ratio modifier curve is normalized to 1 at a part-load ratio of 1 and is used only when the part-load ratio is less than or equal to 1.
This curve defines how the heating energy input ratio (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 heating part-load ratio used as the independent variable. The heating energy input ratio modifier curve is normalized to 1 at a part-load ratio of 1 and is used only when the part-load ratio is greater than 1.
This field defines the heating 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 heating capacity divided by the rated heat pump heating capacity. The curve is either quadratic or cubic 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 in the curve object must be ≥1). The output of this curve provides a multiplier (>1) which is applied to the Nominal Heat Pump Heating 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, capacity is directly proportional to part-load ratio and this curve will not be used. If this field is left blank, the Cooling Combination Ratio Correction factor will be used.
This field defines the heating 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 indoor to outdoor heating capacity ratio is less than the Minimum heat pump part-load ratio.