Stencil: Zone HVAC Stencil: Finned Rad Elec Gas
Type: Radiant Device
Sub Type: RadiantPanelLowTemp_Elec
EnergyPlus Object - ZoneHVAC:LowTemperatureRadiant:Electric
This low temperature radiant system (electric) is a component of zone equipment that is intended to model any “radiant system” where electric resistance heating is used to supply energy (heat) to a building surface (wall, ceiling, or floor). The component is controlled by the radiant system controls and this control does not require the use of a zone thermostat unless the unit is being autosized. Note also that because this unit does not require a thermostat that in cases where no other systems are serving the zone in which this system resides that it will use the heating equipment priority to determine which system will run first. If the radiant system is serving a zone with forced air equipment, the radiant system will follow the priority order established by the zone thermostat but will still base its response on the controls defined by the user for the radiant system.
The control is accomplished by varying the electrical power supplied to the unit. This model covers either a radiant panel system or wires embedded in entire walls, floors, or ceilings. It is not intended to simulate high temperature electric or gas radiant heaters.
The table shows the properties that are displayed when the component is selected while in diagram mode. The second column shows the selection options available that are dictated by EnergyPlus or it shows the source for the library entries that are displayed in the drop down list.
| Property Name | Value Sources/Options |
|
Name |
Simergy provides unique name (editable) |
|
Availability Schedule Name |
|
|
Maximum Electrical Power to Panel |
0-Min; Autosize |
|
Temperature Control Type |
Outdoor Wet Bulb Temperature Outdoor Dry Bulb Temperature Operative Temperature Mean Radiant Temperature Mean Air Temperature |
|
Heating Throttling Range |
0-Min |
|
Heating Setpoint Temperature Schedule Name |
Simergy automatically defines a unique name for each component. This can be changed by the user if desired.
Schedule that this component will operate or is available to operate.
This field is the maximum amount of electrical energy that can be converted to heat in this particular radiant system in Watts. The controls for the radiant system will vary the amount of power supplied to the surface between zero input and the maximum power specified in this field as the lower and upper bounds, respectively. Note that if the user elects to autosize this field that a standard zone thermostat such as would be used for a forced air system must be defined as autosizing calculations are based on the zone thermostat value and not on the radiant system control values.
This field specifies along with the throttling range and setpoint schedules how the user wishes to control the low temperature electric radiant system. The temperature denoted in the setpoint schedule can refer to one of three different temperatures: the zone mean air temperature, the zone mean radiant temperature, the zone operative temperature, the outdoor dry-bulb temperature, or the outdoor wet-bulb temperature. The choice of temperature is controlled by the current field—temperature control type.
Operative temperature for radiant system controls is the average of Mean Air Temperature and Mean Radiant Temperature. If the user does not select a control type, MeanAirTemperature control is assumed by EnergyPlus.
This field specifies the range of temperature in degrees Celsuis over which the radiant system throttles from zero heat input via the electric resistance wires up to the maximum defined by the maximum electrical power field described above. The throttling range parameter is used in conjunction with the control temperature (see below) to define the response of the system to various zone conditions. The heating control temperature schedule specifies the “setpoint” temperature where the power input to the system is at half of the maximum power input. For example, if the heating control temperature setpoint is currently 15°C and the heating throttling range is 2°C, the electrical power supplied to the radiant system will be zero when the controlling temperature (MAT, MRT, Operative Temperature, ODB, or OWB; see control type field above) is at or above 16°C and the maximum power input when the controlling temperature is at or below 14°C. This represents a throttling range of 2°C around the setpoint of 15°C. In between 14°C and 16°C, the power input to the radiant system is varied linearly.
This field specifies the heating setpoint or control temperature for the radiant system in degrees Celsius. Used in conjunction with the previous field (heating throttling range), it will define whether or not the system is running and the current power input to the radiant surface. Power input to the system is varied linearly around the setpoint temperature based on the throttling range and the maximum electrical power parameters (see above). It should be noted that this control schedule will allow different setpoint temperatures throughout the year for heating. In addition, this schedule may be different that the thermostatic control schedule defined for overall operation of components serving the zone in which the radiant system is located. The thermostatic control determines whether or not there is a heating or cooling load in the space and thus whether the systems should be operating. This field simply controls the flow rate to the radiant system.
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