Unit Heaters
Unit heaters are zone equipment units which are assembled from other components and are a simplification of unit ventilators. They contain only a fan and a heating coil. While the control of the heating coil is similar to the fan coil units and the unit ventilator, the overall control of the unit heater is much different. See the input information for the Dead Band Fan Operation.
Note: Standard TRACE library members cannot be modified or deleted but they can be copied and edited.
Nominal Heating Capacity
|
Default: Auto Size box checked
|
|
Typical Range: 41.3 to 705 Mbh
|
|
Min Max: 0 to 1,000,000,000,000,000 (this field cannot be left blank)
|
|
Units: % Htg Capacity; W; kW; W/m2; W/ft2; tons; Btuh; MBh; tons/ft2; Btuh/ft2
|
This checkbox indicates whether or not the capacity used for the selected heating coil will be auto sized by the program or referenced from the user defined input.
Supply Fan
Cycling Mode
|
Default: Cycling Fan
|
|
Typical Range: N/A
|
|
Min Max: N/A
|
|
Units: N/A
|
This is the input used to describe the operational control of the supply fan. Two options are available: Cycling Fan or Continuous Fan.
Supply Fan Placement
|
Default: Blow Through
|
|
Typical Range: N/A
|
|
Min Max: N/A
|
|
Units: N/A
|
This input is used to determine if the supply fan is placed up stream or downstream of the heating coil. Two options are available: Blow Through or Draw Through.
Supply Fan Type
|
Default: Constant Volume
|
|
Typical Range: N/A
|
|
Min Max: N/A
|
|
Units: N/A
|
This is the type of supply fan that is associated with the library member. Two options are available: Constant or Variable Volume.
Supply Air Fan
|
Default: Direct Drive Plenum
|
|
Typical Range: N/A
|
|
Min Max: N/A
|
|
Units: N/A
|
This input selection refers to the name of the fan library member that is used in this object.
Fan Full Load Energy Rate
|
Default: 0.0002 kW/(cfm); Auto Size box is unchecked
|
|
Typical Range: 0.0001 to 0.0004 kW/(cfm)
|
|
Min Max: 0 to 1,000,000,000,000,000 (this field cannot be left blank)
|
|
Units: W; kW; W/(m3/sec); W/(m3/sec)-Pa; W/(cfm); W/(L/sec); W/(L/sec)-Pa; kW/(cfm); kW/(L/sec); kW/(cfm)-in H2O; kW/(L/sec)-Pa; W/(cfm)-in H2O; bhp
|
This checkbox indicates whether or not the full load energy rate used for the selected fan will be auto sized by the program or referenced from the user defined input.
Pressure Rise
|
Default: 4 inches H2O, Auto Size box is unchecked
|
|
Typical Range: 0.25 to 5 inches H2O
|
|
Min Max: 0 to 1,000,000,000,000,000 (this field cannot be left blank)
|
|
Units: inches H2O; lb/ft2; psig; Pa; kPa; mm Hg; mm H2O; bar; in Hg; atm; mm CE; m CE; m H2O; mbar
|
The value will be populated by default based on the fan library member selected. You can override this value and the units of measure.
Dead Band Fan Operation
|
Default: Yes
|
|
Typical Range: N/A
|
|
Min Max: N/A
|
|
Units: N/A
|
There are two dead band modes in which the Unit Heater can operate based on the user input: Yes or No. When No is specified, the supply fan will be off when no heating load is present despite the fan Cycling Mode selected. When Yes is specified, the fan will operate when no heating load is present as long as the fan Cycling Mode is set to continuous.
Dead Band Airflow
|
Default: Auto Size box is checked
|
|
Typical Range: N/A
|
|
Min Max: 0 to 1,000,000,000,000,000 (this field cannot be left blank)
|
|
Units: m3/sec; cfm; cfm/ft2; (m3/s)/m2; % Clg Airflow; % Htg Airflow; L/s; m3/hr; (m3/hr)/m2
|
This numeric field defines the supply air flow rate leaving the Unit Heater when no heating is required (i.e. the heating coil is not operating). This field is only used when the Unit Heater’s dead band mode supply fan operation option is set to Yes.
Unitary Heating Type
Unitary Heating Type
|
Default: Electric
|
|
Typical Range: N/A
|
|
Min Max: N/A
|
|
Units: N/A
|
This field specifies the type of heating coil to model for this Unit Heater. Four options are available to choose from: Electric, Gas, Steam, Water.
Unitary Heating
|
Default: Electric Heating coil
|
|
Typical Range: N/A
|
|
Min Max: N/A
|
|
Units: N/A
|
This field allows you to select the heating coil library member that will be used for this Unit Heater equipment.
Unitary Heating Design Airflow
|
Default: Auto Size box checked
|
|
Typical Range: 200 to 5500 cfm
|
|
Min Max: 0 to 1,000,000,000,000,000 (this field cannot be left blank)
|
|
Units: cm3/s; m3/s; cfm; cfm/ft2; (m3/s)/m2; % Htg Airflow; cfm/ton; (m3/s)/(kW); (m3/hr)/(kW); (m3/s)/(W); m3/hr ; m3/hr/m2
|
This input refers to the design heating airflow value associated with the Unit Heater library member. This input can be used to scale the size of the coil as well.