Terminal Units
The difference between a series fan box and a parallel fan box.
What is the placement and function of the fan.
How are they different?
This is how we quantify a product's sound level in most mechanical schedules.
What is NC or Noise Criterion.
What is NC? Why can it be problematic to schedule?
This is the difference between a grille and a register.
What is a register has an OBD on the back.
Why is this important?
This hydronic air distribution product works best in sensible-only applications.
What is a chilled beam.
How do they work?
What is a round throw pattern.
Why is it round, not square?
This is how we measure airflow within a standard construction terminal unit.
What is by measuring pressure with a crossflow sensor.
How do we relate pressure measurement to airflow?
These are the two types of sound emitted by a terminal unit.
What are discharge sound and radiated sound.
How are these different?
This is the location where you would usually try to place a return diffuser compared with a supply.
What is opposite the supply diffuser in the room.
Why?
This air distribution system is well suited for use in large atria, auditoriums or airports.
What is a displacement ventilation or underfloor system.
Why would these be useful for those type of spaces?
This is the effect of throwing air across a surface to maximize that air throw.
What is the Coanda Effect.
What does that mean? How does it work?
The pressure an air handler is responsible for in a VAV system.
What is inlet static pressure.
Why is this important?
Sound power is at the ____ and sound pressure is at the _____.
What is source and receiver.
Why do we care about this? What is dBA?
What is isothermal air.
Why is this important?
This air distribution technology utilizes higher supply air temperatures and far lower air velocities to cool spaces.
What is displacement ventilation.
Where and how can DV add value?
This is what the 3 throw numbers mean in catalogued GRD performance.
What is the distance to 150, 100 and 50fpm terminal velocities.
Why is that important?
This is the industry standard differential pressure range for setting VAV minimum and maximum airflows.
What is 0.02" - 1.5" of static.
Why is this important?
This is what a 10dB difference sounds like in a space.
What is either twice as loud or half as loud.
What happens when we have multiple items at the same sound level in close proximity?
This type of diffuser inlet condition creates the mots severe deviation from catalogued performance.
What is a sharp elbow in the supply duct.
Why?
These are the two types of chilled beams available in the market.
What is an active (or forced air) and passive (convection only).
How are these different and why is it important?
In ADPI calculations, this is the defined distance between diffusers to maximize their performance for occupant comfort.
What is the Characteristic Length.
Can you define the different types of characteristic length and why?
This is the biggest limitation for turning down airflow in a single duct VAV box.
What is the pressure transducer on the controller.
Why do we care about this?
These are the best ways to mitigate acoustic issues with terminal units in general.
What are discharge attenuators or silencers (for discharge sound) and layers of acoustic ceiling tiles (for radiated sound).
Do single duct boxes have radiated noise?
This ASHRAE-created design criteria for air distribution layouts helps designers decide where to put diffusers.
What is call Air Diffusion Performance Index, or ADPI.
Why is this important? What does it do?
These are some of the major benefits for displacement, underfloor and chilled beam systems.
What are improved acoustics, improved energy usage, reduced plenum space height (aka reduced facade costs, or higher interior ceilings), and more.
What other benefits can you think of?
This is how diffuser performance changes when in cooling or in heating, vs. catalog performance.
What is a 1% difference per 1deg of temperature differential.
What does this mean for horizontal vs. vertical, cooling vs heating throw?