This alpha field contains the unique identifying name for the water to water heat pump.
You can use this control to load data to the dialog from a pre-defined heat pump template as a starting point for your particular heat pump component. A sample list of manufacturers data is provided in the templates and instructions on how to create your own templates from manufacturers data.
Heat pumps are usually selected using their Rated heating capacity.
DesignBuilder provides the EnergyPlus Equation Fit water to water heat pump model. EnergyPlus also provides the Parameter Estimation model but this only supports R22 refrigerant which is no longer permitted in new designs. Because of this and other technical limitations in the model, DesignBuilder have now removed this option so the Type control is currently disabled and is fixed as 1-Equation fit.
This numeric field contains the rated volumetric flow rate on the load side of the heat pump in (m3/s or gal/min). This corresponds to the highest load side heat transfer rate listed in the catalogue data.
This numeric field contains the rated volumetric flow rate on the source side of the heat pump in (m3/s or gal/min). This corresponds to the highest load side heat transfer rate listed in the catalogue data.
This numeric field contains the rated heating capacity of the heat pump in W. This corresponds to the highest load side heat transfer rate listed in the catalogue data.
This numeric field contains the rated power consumption of the heat pump in W. This corresponds to the highest load side heat transfer rate listed in the catalogue data.
Five fields are used to describe the coefficients for the Heating capacity curve. More details on how these coefficients are used are provided in the technical section of the Water to water heat pumps page and in the Engineering Reference.
These numeric fields contain the five coefficients for the heat pump capacity.
Five fields are used to describe the coefficients for the Heating compressor power consumption curve. More details on how these coefficients are used are provided in the technical section of the Water to water heat pumps page and in the Engineering Reference.
These numeric fields contain the five coefficients for the heat pump power consumption.
The full on and off cycle time of the heat pump unit in hours. You are advised to leave this data at the default value of 0.0161 hours (1 minute) which is also the minimum value. The maximum allowed value is 0.1 hours (6 minutes) but note that using values higher than the default can prevent correct operation of the heat pump.
The highest supply water temperature provided in catalogue data for heating heat pumps is normally between 50ºC-60ºC. This is not generally hot enough to supply hot water radiators and heating coils. However, EneryPlus does not limit the output water temperature to the catalogue maximum, so in practice, if setpoints allow it, supply water temperatures can achieve the typical hot water radiator/baseboard temperature levels of 75ºC-80ºC.
The figure below uses Carrier model 50PSW036 (highest leaving water temperature 51.8ºC) heating as an example to show the impact of using heat pumps outside their intended operation regime. Extrapolation of catalogue data is not normally recommended however a simple trend line (following red coloured line) shows that the COP of the heat pump will be much reduced at ~1.38 when output water temperature reaches 80ºC. So this sort of system configuration is clearly not as energy efficient as a low temperature system such as a heated floor which require supply temperatures around 35ºC and give COPs of over 4 at this leaving water temperature. Underfloor heating is therefore recommended for use with GSHP.