Multizone Equitment

Question 1

What are the two main reasons we use zoneing systems in hvac design.

Answer 1

Comfort and efficiency

Question 2

Why do zoneing systems save energy compaired to non zoneing systems?

Answer 2

Because if only one zones needs conditioning then the other dampers will close and less heat required

Question 3

What are three ways that vav boxes are controlled?

Answer 3

Pneumatically
Motorized
Automated control systems [acs]

Question 4

Why are vac boxes popular in light commercial construction?

Answer 4

Because of the versatility they provide when the zones need to be changed.

Question 5

Which type of vav is typically used in offices and why ?

Answer 5

Vav diffusers because comfort and individual control
Control of required air volume for each zone
Ease of installation and relocation
Flexibility for future
Ease of maintenance

Question 6

What is used in conjunction with vav boxes to help heat extieror zones in winter months?

Answer 6

Reheat coils

Question 7

List 7 types of vav terminals in large construction

Answer 7

Single duct with reheat coil
Dual duct non mixing
Dual duct mixing
Fan powered constant (series)
Fan powered variable (parallel)
Induction terminals dual
Induction terminals single
Vav diffusers

Question 8

Describe the function of a dual non mixing vava terminal?

Answer 8

Two duct inlets one provides warm air one provides cold air

Do not mix just have dampers that open or close due to what thermostat is calling for

Question 9

What is the primary difference between dual duct non mixing and dual duct mixing boxes?

Answer 9

The dual duct that mixes has a set of perforated baffles s that mix the two airstreams which are individually modulated depending on zone demand

Question 10

What are the 2 types of fan powered vav terminal units

Answer 10

Constant volume (series)
Varaible volume (parellel

Question 11

What are 5 advantages of vav diffusers

Answer 11

1 individual space control and comfort
2. Control of required air volume for each zone
3. Ease of installation and relocation
4. Flexibility for future requirements
5. Ease of maintenance

Question 12

True or false a multizone air handler delivers low pressure high velocity air

Answer 12

False it’s high pressure low velocity

Question 13

What’s more economical a 2 deck ahu or a 3 deck ahu

Answer 13

3 deck

Question 14

What does vav stand for

Answer 14

Variable air volume

Question 15

What are the two types of bypass dampers

Answer 15

Barometric and motorized

Question 16

What is the difference between independent and dependent vavs?

Answer 16

Independent measures the volume in cfm and maintain the proper airflow

Dependent the cfm will change depending on the inlet static pressure

Question 17

What will happen in some hvac systems that are zoned if no bypass damper is installed ?

Answer 17

You will get to much air , unwanted noise , exseccsive drafts and can cause damage to the hvac unit

Question 18

Results in closing off to many outlets reducing airflow in residential furnace

Answer 18

Increased temp rise
high limit goes off

Question 19

Commonly used on entiro zones in a building where hot water or reheat coils are not an option ?

Answer 19

Dual duct vav

Question 20

When referring to a fan powered vav what happens to primary air when the system is in heating mode ?

Answer 20

Closes but never 100%

Question 21

What kind of induction terminal unit requires both a heating and cooling coil in the unit ?

Answer 21

Single duct unit