Air-air conditioning systems. Air handling unit, variable flow all-air system with double duct
Dual-duct systems have two supply ducts, one for cold air and one for warm air. The terminal units are mixing boxes to which both ducts lead. In the case of variable airflow systems, the fan is variable speed. The terminal units are mixing boxes that also have dampers for varying the flow rate. The fans will always be running.
Air handling unit, variable flow all-air system with double duct. “Air conditioning” tab
Cooling (optional)
- Cooling coil (Cold water)
This sets the characteristics of the cooling coil:- Cold water
- Chilled-water system
Allows users to select a chilled-water system defined in the "Air conditioning systems" section.
- Chilled-water system
- Advanced configuration
- Automatic sizing options
- Design supply temperature
- Temperature control
- Maximum temperature
This option calculates the supply air temperature needed to overcome the cooling demand of the critical zone at the maximum supply flow rate. This temperature shall be as high as possible. Therefore, this strategy minimises the cooling generator consumption in exchange for higher fan consumption. - Minimum temperature
This option calculates the supply air temperature needed to overcome the cooling demand of the critical zone at the maximum supply flow rate. This temperature shall be as low as possible. Therefore, this strategy minimises the cooling generator consumption in exchange for higher fan consumption.- Minimum air flow fraction
The minimum air flow fraction must match the one defined in the terminal units connected to this unit.
- Minimum air flow fraction
- Maximum temperature
- Automatic sizing options
- Cold water
Heating (optional)
- Heating coil (Direct expansion / Electric / Gas)
This sets the characteristics of the heating coil:- Hot water
- Hot-water system
Allows users to select a hot-water system defined in the "Air conditioning systems" section.
- Hot-water system
- Electric
- Gross rated capacity (optional)
- Gas
- Gross rated capacity (optional)
- Advanced configuration
- Gas heating coil efficiency
- Parasitic electric load
- Advanced configuration
- Automatic sizing options
- Design supply temperature
- Automatic sizing options
- Hot water
Supply fan
- Advanced configuration
- Horario de funcionamiento (Siempre encendido / Sólo con la Working hours (Always on / Only with active ventilation)
- Automatic air flow calculation (Simultaneous / Total)
- Simple fan
- Main fan
- Motor efficiency
- Motor heat losses fraction in air stream
- Maximum air flow rate (optional)
- Specific power
- Main fan
- Dual fan
- Cooling duct fan
- Motor efficiency
- Motor heat losses fraction in air stream
- Maximum air flow rate (optional)
- Specific power
- Heating duct fan
- Motor efficiency
- Motor heat losses fraction in air stream
- Maximum air flow rate (optional)
- Specific power
- Cooling duct fan
Air handling unit, variable flow all-air system with double duct. “Outdoor air inlet” tab (optional)
If the “Outdoor air inlet” tab is deactivated, the system only recirculates air from the heating zones.
Free cooling (optional)
Heat recovery (optional)
- Sensible effectiveness
- Latent effectiveness (optional)
- Advanced configuration
- Heat exchanger type (Plate / Rotary)
- Frost control type (None / Exhaust air recirculation / Exhaust only / Minimum exhaust temperature)
Return fan (optional)
- Specific power
- Advanced configuration
- Motor efficiency
- Motor heat losses fraction in air stream
- Part-load power coefficients (Inlet vane dampers / Outlet dampers / Variable speed motor / ASHRAE 90.1-2004 Appendix G / Variable speed motor pressure reset)
Air handling unit, variable flow all-air system with double duct. “Humidity control” tab
Dehumidification (optional)
The dehumidification of the air is carried out by its cooling and subsequent reheating.
- Relative humidity setpoint
- Control zone
The control zone is that which contains the thermostat associated with this equipment. A zone that contains a terminal unit connected to this equipment must be selected.
Humidification with steam (optional)
- Relative humidity setpoint
- Control zone
The control zone is that which contains the thermostat associated with this equipment. A zone that contains a terminal unit connected to this equipment must be selected. - Steam flow, nominal
- Humidifier rated electric power (optional)
