PDX_19_Hvac Details And Constructibility Flashcards
Single blade dampers that is hinged at one end and installed to divert air from the main duct into a branch duct
Splitter damper
The means for delivering heating and cooling
Distribution trees
A curved fin that fits inside adduct to direct the airflow to another direction without adding noise to the system
Turning vane
A small amount of supply air and a very high velocities delivered to a box and mixed with air brought in from the room inducing a greater airflow
Induction
Noncombustible and heat resistant passage in the chimney used to convey products of combustion from furnace, fireplace, or boiler to the atmosphere
Flue
Enclosure in which to airstreams are mixed, commonly used in a dual duct system
Mixing box
Water intentionally wasted from the boiler to avoid concentration of impurities during evaporation of steam
Blowdown
Watered used to supply a boiler to generate steam or hot water
Feedwater
To find the cross-section area of a duct:
144 x ( flow rate in cubic feet per min.)
/ velocity measured in ft/min
To measure friction loss in a circular duct:
0.109136 CFM ^1.9
/ equivalent duct diameter ^5.02
To reduce size on lower building floors
Utilize a distribution tree that flows from a rooftop central AHU
High velocity ducts are anything over:
2500 ft./m
Low velocity ducts at speeds:
1000-2200 ft./m
Most common material for vents and ducts:
Sheet-metal made of galvanized steel or aluminum, because most durable and least likely to have mold/bacteria growth
A duct material option other than sheet-metal:
Fiberglass lined, used to insulate dryer ducts from heat loss, to avoid condensation, and or to reduce sound.
Hey valve or plate that stops or regulates the flow of air inside a duct:
Damper
Most common type of fan
Bladed fan
Fan used for moving large amount of air:
Centrifugal fan
These reduce velocity and sound has air enters the space from ductwork
Diffusers
Chimney height must be:
2 feet higher than any part of the roof within 10 feet horizontal.
In the HVAC design process, component sizing typically occurs before:
Resolving conflicts with other building systems.
Locating a heat source below window evens out the temperature in the room, but:
Increases heat loss through the window
Mechanical room space requirements for medium to large buildings with air or air/water systems should be:
3-9% of gross building area for air or air/water systems
Mechanical room space requirements for medium to large buildings with water systems should be:
1 - 3% for water systems
The space for the mechanical room needs to be
Twice the length of the major equipment and 12 - 18 ft tall
