Commercial HVAC and Drawings

Question 1

How could a constant air volume system best be described?

Answer 1

Constant air flow in the system and the temperature will vary

Question 2

Provide some applications for a constant air volume system

Answer 2

Homes, restaurants, offices, apartments, supermarkets, labs, plants etc.

Question 3

What are some system variations for constant air volume systems?

Answer 3

Reheat and multi-zone

Question 4

Why are constant air volume systems often the system of choice?

Answer 4

Simple, low cost and reliable

Question 5

What is VAV?

Answer 5

Variable air volume.

Question 6

What is the supply air temperature for a VAV system?

Answer 6

55°f or 13°c

Question 7

What are two styles of VAV systems?

Answer 7

Regular and True.

Question 8

How do these two styles differ?

Answer 8

In a regular VAV system the fan speed does not vary

Question 9

How much energy can be saved in a VAV system?

Answer 9

20% to 30%.

Question 10

How many air inlets are there on a VAV box?

Answer 10

One

Question 11

How does a single duct system differ for a dual duct system?

Answer 11

Single duct has a single air path for the supply air to travel and having variable temperature. Dual path for supply air one hot and one cold air will mix at box.

Question 12

The mixing of the two air streams occurs where in a dual duct VAV system?

Answer 12

Mixing will occur at the box near the zone.

Question 13

Describe how a dual duct system can provide better air flow to the conditions space.

Answer 13

A dual duct system does not need to go to minimal air flow requirements for heating mode.

Question 14

How does the air volume vary in a bypass system?

Answer 14

A bypass will dump the unwanted air and will return back to the unit without entering the conditioned space.

Question 15

Reheat coils are either hot water coils or electric coils and are located in or close to the zone. True or False?

Answer 15

True

Question 16

For higher velocity systems the air velocities must be slowed down before entering the conditioned space. What is used to achieve this?

Answer 16

Attenuator box

Question 17

Where are inductions systems often found?

Answer 17

They are used in larger building vestibules and under large windows.

Question 18

Building exhaust air systems require make-up air systems why?

Answer 18

Building exhaust air systems can create a negative pressure in a building which can cause problems with drafts and venting systems etc. this is why the air must be made up.

Question 19

List the two types of gas fired make-up air units.

Answer 19

Indirect and direct fired gas units.

Question 20

How do these two types differ?

Answer 20

The combustion happens in the supply airstream and contains the products of combustion. In an indirect gas fired unit the combustion process happens in a combustion chamber and there are vented outdoors

Question 21

What is the temperature range for most gas fired make-up air units?

Answer 21

50°f (13°c) to 100°f (38°c)

Question 22

In what type of application are makeup air units used?

Answer 22

They are used in commercial kitchens, gyms, stadiums, car dealers, labs etc.

Question 23

In direct fired makeup air units the flue gases from combustion discharged through the flue to the outdoors”. True or false

Answer 23

False

Question 24

Must the exhaust air and makeup air systems be interlocked?

Answer 24

Yes

Question 25

How much makeup air is required in relationship to exhaust?

Answer 25

100%

Question 26

Where are the reheat-coils located in a low pressure constant volume reheat system

Answer 26

In the zone

Question 27

What is an Attenuator box?

Answer 27

To slow air down and reduce pressure of the air.