Deck 49: Operation, Maintenance, and Troubleshooting of Chilled-Water Air Conditioning Systems

Question 1

When a water-cooled chiller is operating normally, it can usually be left unattended, except for which component?

A) The condenser.
B) The evaporator.
C) The metering device.
D) The cooling tower.

Answer 1

D

Question 2

The ____________________ is used in water circuits and is a quick-shutoff valve̶ as it only needs to be turned one-quarter turn from on to off, like a ball valve.

Answer 2

butterfly valve

Question 3

The safety switch in the chilled water line that is activated by water flow is called a(n) ____________________.

Answer 3

flow switch

Question 4

After chemically cleaning a condenser, it is extremely important to make sure that the chemicals are neutralized or the tubes may be damaged.

Question 5

The first step in starting a chilled-water system is to ____.

A) activate the compressor unloading system
B) establish the chilled-water flow
C) activate the condenser heat removal system
D) start the compressor operation sequence

Question 6

Ball valves for refrigerant piping are used for larger applications and come in sizes up to about   ____________________ .

Question 7

There should be a ____ test point at the inlet and outlet of any water heat exchanger, chiller, or condenser.

A) temperature
B) pressure
C) vapor
D) moisture

Question 8

The operation of chillers involves starting, running, and stopping the system's components in an orderly manner.

Question 9

Chillers manufactured in the last few years all have ____ controls.

A) electronic
B) hydraulic
C) pneumatic
D) pressure-based

Question 10

Low-pressure chillers operate in a vacuum and will stay in a vacuum if the equipment room is not warm enough to keep the refrigerant warm.

Question 11

Centrifugal chillers range in size from ____ tons for a single chiller.

A) 10 to 50
B) 10 to 80
C) 50 to 500
D) 100 to 10,000

Question 12

If an absorption chiller makes an "ice-crackling" sound, it is an indication that no condenser water is flowing.

Question 13

The ____________________ creates much less pressure drop through the valve than the globe valve and is a much better application where excess pressure drop is a concern.

Question 14

Water-cooled chillers must have water treatment to ____.

A) increase the pH content of the water in the sump
B) decrease the pH content of the water in the sump
C) prevent minerals and algae from forming in the water circuit
D) help preheat the water in the condenser water circuit

Question 15

The scroll-chiller compressor needs crankcase heat and it must be energized for the length of time the manufacturer requires, usually____________________ hours.

Question 16

What may happen if a lithium-bromide absorption system is started with the cooling water too cold?

A) High head pressure in the system.
B) Low head pressure in the absorber.
C) Removal of system load, compressor cylinders will unload.
D) Crystallization occurs.

Question 17

If the purge unit on a chiller is operating very frequently, the system may have a leak.

Question 18

A typical chilled water system is designed to operate with a leaving water temperature of ____°F.

A) 35
B) 40
C) 45
D) 50

Question 19

Reciprocating chillers have crankcase heaters to ____.

A) preheat the chilled water for better efficiency
B) prevent refrigerant migration to the crankcase
C) preheat the compressor bearings for longer wear
D) minimize condenser subcooling

Question 20

The technician should also be aware of the ____________________ through the contactors that must be satisfied before startup.

Question 21

After being cleaned, the condenser tubes may be checked for stress cracks, erosion, wear on the outside and other defects, by means of what type of instrument?

Question 22

What is meant by the term "blowdown"?

Question 23

There are three lines of defense against refrigerant leaks in a service valve: the back seat, the packing gland, and the ____________________.

Question 24

To remove particles that may be in suspension and circulating in a water circuit, a(n) ____________________ is used.

Question 25

How are reciprocating, scroll and rotary compressors lubricated?

Question 26

If an absorption unit is started with very cold water in the cooling tower, the lithium bromide in the unit may ____________________.

Question 27

Before allowing the compressors of a water-cooled chiller to start up, what two things must be done?

Question 28

If the compressor motor megohm value begins to decrease, it is a sign that ____________________ or some other foreign matter may be getting into the system.