Distribution Systems

Question 1

Air distribution arrangements:
1. single \_\_\_\_
2. terminal \_\_\_\_\_\_\_
3. induction \_\_\_\_\_\_
4. \_\_\_\_\_ zone
bypass \_\_\_\_\_ zone (terminal reheat)

Answer 1

1. single zone
2. terminal reheat
3. induction reheat
4. multizone
5. bypass multi zone (terminal reheat)

Question 2

Distribution arrangements can have two different types of air flow;
1.
2.

Answer 2

1. constant volume

2. variable volume

Question 3

Residential is all ______ duct because it is cheaper

Answer 3

single

Question 4

Single zone distribution characteristics:

1. responds only to one zone or ______ condition
2. can be single or _____ fan
3. can incorporate reheat coils for __________
4. economizers can be used when OA is below ___
5. constant volume or _______ volume air flow
6. energy efficiency is ______

Answer 4

1. space
2. dual
3. dehumidification
4. 55F
5. variable
6. good

Question 5

If static pressure in return is too high in return duct what happens?

Answer 5

It will be exhausted outdoors

Question 6

Terminal Reheat Distribution:

1. Modification of single zone air and ______ systems
2. Responds to ______ zones or space conditions
3. can be single or _____ fan
4. incorporates a ______ coil at each zone for individual temp control
5. Terminal box can be reheat unit (medium velocity) or _______ unit (high velocity)

Answer 6

1. water
2. multiple
3. dual
4. reheat
5. induction

Question 7

Single Duct Terminal Reheat:

1. Primary air supplied down the duct at approx ___F
2. the air is reheated at the zone on a call for heat at the zone ________
3. used in large buildings with many zones with large variations in ____
4. ____ an energy efficiency system

Answer 7

1. 55F
2. thermostat
3. load
4. NOT

Question 8

What does AHU mean?

Answer 8

Air handling unit

Question 9

What is a system that does not have any return air called?

Answer 9

make up air

Question 10

What happens when you block multiple diffuser outlets?

Answer 10

over pressurization in ducts

Question 11

What is the best way to fix over pressurization?

Answer 11

variable speed motor that can adjust to whatever demand is required

Question 12

What are VAV terminals? (Square/round box before diffuser outlet)

Answer 12

They talk to thermostats to adjust cooling/heating needs

Question 13

VAV terminals sometimes have an electrical _______ coil at the terminal

Answer 13

reheater

Question 14

VAV terminals control flow of air with _______ on the inlet

Answer 14

dampers

Question 15

If the thermostat tells the VAV it is too cold in the room it will _______ the damper to bring in less cool air

Answer 15

adjust

Question 16

Some reheat coils are hot ______ fed

Answer 16

hot water fed

Question 17

Where are economizers located?

Answer 17

outside air hood

Question 18

What is an enthalpy/temp sensor on an economizer?

Answer 18

tells the controller to open or close damper based on latent/sensible

Question 19

Economizer:

As outdoor air damper begins to modulate open the return air damper will begin to modulate closed to ensure correct ______ air is maintained

Answer 19

mixed

Question 20

Some economizers use outdoor air as ____ cooling for the building

Answer 20

free

Question 21

Set economizer at A,B,C,D settings based on what factors

Answer 21

temperature and relative humidity

Question 22

Single Duct; Terminal Reheat Distribution:

1. economizers can be used to save on _______ costs
   - energy efficiency is poor
2. Induction units were designed for use in exterior rooms of multi story buildings where a high sensible loss occurs, yet at the same time cooling is required in the interior of the building

Answer 22

1. cooling

Question 23

*Single Duct; Terminal Reheat Distribution; Induction Unit:

1. Coils: Dual temp ______ (DTW) System
2. Low/Med/High (LMH) __ System

Terminology:

1. Primary air (______ from main equipment plenum)
2. Secondary air (room induced by ________)

Answer 23

1. water
2. TW
3. supply
4. primary

Question 24

An induction box uses the Bernoulli principle to draw room air in and mix with the ______ air

Answer 24

primary

Question 25

Difference between an induction unit and VAV?

Answer 25

induction unit is a VAV but adds induced air for mixing purposes

Question 26

Single Duct; Multi-zone: Modification of single duct system; All Air System 1. Two separate plenums; 1 for _____, 1 for ______

Answer 26

1. heat, cool

Question 27

Single Duct; Multizone 1. Responds to multi-zone or space conditions (normally __ or less) 2. Hot deck temperature is determined by _______ stat 3. Cold deck temp maintained at __F 4. Zone air is mixed by zone mixing dampers located within ____ ________

Answer 27

1. 12 or less 2. outdoor stat 3. 55F 4. main plenum

Question 28

what are mixing boxes used for?

Answer 28

to maintain temperatures so there is not swing in room temp from furnace coming on/off

Question 29

Single Duct; Multizone 1. ____ supply duct to each zone 2. economizers can be used 3. Fan arrangement is _____ through 4. Induction unit __ normally used 5. Constant _______

Answer 29

1. one 3. blow 4. not 5. volume

Question 30

Single Duct: Bypass Multizone; Modification of multizone; 1. Air and Water system: Has ___ separate plenums; 1 for _____, 1 for ______ cool 2. cold deck is maintained at ___F

Answer 30

1. one for cool, one for bypass cool | 2. 55F

Question 31

Single Duct: Bypass Multizone 1. Responds to _____ or space temperatures 2. Normally used in milder climates as it uses return air heated by space as ______ heat 3. If further heating is required the system is equipped with _______ ______ coils at terminal box of each zone

Answer 31

1. zone 2. primary 3. terminal reheat coil

Question 32

Single Duct: Bypass Multizone; 1. Terminal box may be ________ type 2. Fan arrangement is ____ ______ 3. Air supply is ______ ________

Answer 32

1. induction type 2. draw through 3. constant volume

Question 33

Dual Duct System; 1. Most ________ type of system 2. All air system 3. Responds to unlimited number of _____ 4. Fan arrangment can be of two types; what are they?

Answer 33

1. expensive 3. zones 4. draw through or blow through

Question 34

Dual Duct System; 1. Has two separate ducts; what are they? 2. ________ boxes located at each zone 3. Economizers not _________ 4. Single or _____ fan

Answer 34

1. hot duct, cold duct 2. Mixing 3. recommended 4. single or dual fan

Question 35

Name a system that is NOT energy efficient

Answer 35

single duct terminal reheat

Question 36

minimum fresh air?

Answer 36

20%

Question 37

What applications are single duct terminal reheat systems used?

Answer 37

used in large buildings with variations in load

Question 38

What type of system responds to an unlimited number of zones?

Answer 38

dual duct

Question 39

Fan arrangement for single duct bypass multizone?

Answer 39

draw through

Question 40

fan arrangement for single duct multizone?

Answer 40

blow through

Question 41

Are induction units normally used in single duct multizone?

Answer 41

no

Question 42

Where do Single Duct; Terminal Reheat Distribution; Induction Units get their primary air and induced air from?

Answer 42

primary air from main supply plenum secondary air from primary air

Question 43

why would a single zone distribution system have a reheat coil?

Answer 43

dehumidification

Question 44

Name two types of reheat coils?

Answer 44

hot water reheat or electric reheat

Question 45

What is meant by induced air?

Answer 45

pulled in room temp air from the space

Question 46

name five air distribution arrangements:

Answer 46

1. single zone 2. terminal reheat 3. induction reheat 4. multizone 5. bypass multi zone (terminal reheat)