Com airside 1
In VAV systems with a return air fan, the fan provides
the amount of air the supply fan is moving, minus the outside air
Which type of system is designed to maintain a constant supply air temperature between 50°F and 60°F year-round?
VAV
In order to modulate the flow of supply air, VAV systems may use inlet guide vanes on the fan inlet or _____.
variable speed drives
All air systems equipped with direct expansion (DX) coils are commonly used in buildings requiring a cooling capacity below_____?
100 Tons
An internal building air pressure normally sufficient to prevent infiltration is between ____?
0.05 & 0.10 in wg.
The maximum safe concentration of carbon dioxide (CO2) in an occupied space is
1,000 ppm
In a VAV system, the demand for heat is satisfied by _____.
a heater attached to the VAV terminal
Which type of economizer is capable of choosing between the use of outside air or return air, based on the enthalpy of the two airstreams?
Integrated economizers
A unit equipped with a 4 way reversing valve is the ____?
Packaged heat pump.
A preheat coil is installed upstream of the cooling coil in an air handler in order to _____?
Prevent the coil from freezing.
Assume a single-zone constant-volume system with an economizer is installed. In the occupied mode, when the thermostat calls for cooling, which of the following occurs?
The economizer acts as the first stage of cooling, if conditions permit
When a parallel fan-powered VAV box is in the heating mode, the primary air damper is _____.
at its minimum position setpoint
The simplest form of economizer control is the _____.
dry-bulb method
The type of fan used in the highest pressure applications is the ____?
Airfoil
A building requiring a cooling capacity of under 20 tons with small control zones typically would use a _____?
VVT system.
A multi-zone constant volume system is well-suited for buildings in which
the control zone arrangement is permanent
What characteristic makes a grille into a register?
An adjustable damper installed behind the face
The packaged unit accessory used to prevent compressor oil from absorbing refrigerant is a(n) _____.
crankcase heater
A year round air conditioner (YAC) is so-called because ____?
Has a gas heating system.
What metal is available as an option for condenser coils that must operate in certain corrosive atmospheres?
Copper
What is one characteristic that sets VVT systems apart from the other approaches
The need for a bypass damper
The primary source of heat for a year-round packaged air conditioner is _____.
natural gas
Comfort is normally associated with the air properties of _____.
temperature and relative humidity
The best location to install a cooling diffuser delivering cool air is in the ____?
Center of the ceiling.
In order to improve part load humidity control with small rooftop units, the option that can be used to raise the unit's discharge air temperature to 75 degrees F at par load is a(n)_____?
Reheat coil