CV Reheat

Stencil: Zone HVAC Stencil: Grp-CV Term w/reheat

Type: Air Terminal

Sub Type: ConstantVolume_Reheat

Note: Requires a connection to a hot water loop

EnergyPlus IDF Objects

EnergyPlus Object - AirTerminal:SingleDuct:ConstantVolume:Reheat

The AirTerminal:SingleDuct:ConstantVolume:Reheat or terminal reheat system is a constant volume reheat system. The systems cooling capabilities are provided by way of cooling coil that supplies cooling to the entire supply air volume. The cooling coil is controlled by a controller setpoint specified for the cooling coil. Zone control is accomplished by heating (reheating) the airflow into each zone as determined by the zone thermostat. Currently the reheat can be supplied by a electric, gas, or hot water coil that tries to meet the zone demand.

Component Properties

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 Air Flow Rate	0-Min, Autosize
Reheat Coil Name	Libraries/Plant and Equipment/Coils & HX Eqmt
Maximum Hot Water or Steam Flow Rate	0, Autosize
Minimum Hot Water or Steam Flow Rate	0-Min; 0 default
Convergence Tolerance	0-Min; 0.001 Default
Maximum Reheat Air Temperature	32C-Min

Name

Simergy automatically defines a unique name for each component. This can be changed by the user if desired.

Field: Availability Schedule Name

Schedule that this component will operate or is available to operate.

Field: Maximum Air Flow Rate

The design constant volume flow rate (m³/sec) specified for the terminal reheat ADU.

Field: Reheat Coil Name

Reheat Coil Object name being simulated with this ADU. Applicable for all coils.

Field: Maximum Hot Water or Steam Flow Rate

This field is 0 for gas and electric coils. Set to the maximum design water flow (m³/sec) for the hot water coil

Field: Minimum Hot Water or Steam Flow Rate

This field is zero for gas and electric coils. Set to the minimum design water flow (m³/sec) for the hot water coil, normally set to be a shut off valve that is set to zero.

Field: Convergence Tolerance

The coil is controlled by knowing the zone demand determined by the zone thermostat and setting the outlet conditions to meet this demand. For the electric and gas coils, this is set exactly since the coil model solution can be inverted. With the hot water coil that uses an effectiveness-NTU method, the solution cannot be inverted directly. Therefore, to determine the correct mass flow rate for the hot water the solution is solved for by iteration. The iterative solution uses an interval halving routine and needs a termination criteria that is set with the Convergence Tolerance parameter. This control offset is set to a decimal fraction of the zone demand as the criteria, i.e. 0.001. The default for the field is 0.001.

Field: Maximum Reheat Air Temperature

This is the upper limit on the temperature in degrees C of the air leaving the terminal unit – reheat coil (and being delivered to the zone). If the user leaves this field blank, no maximum reheat air temperature is enforced.

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