WHAT REGULATE THE FLOW OF CHILLED WATER THROUGH THE COOLING COIL?
A CONTROL VALVE
WHAT SHOULD ALWAYS BE RUNNING WHEN THE CHILLER IS OPERATING
CONDENSER- COOLING WATER PUMP
CAVITATION IN A WATER CONTROL VALVE CAN BE CAUSED BY
EXCESSIVELY HIGH PRESSURE DROP THROUGH THE VALVE
WHAT DO AIR-QUALITY SENSOR MEASURE
CO2, ENTHALPY, AND HUMIDITY
WHAT INPUT SENSOR IS FOUND IN THE FAN SECTION
SUPPLY AIR TEMPTERATURE SENSOR
WHAT INPUT SENSOR IS FOUND IN THE FILTER SECTION
MIXED-AIR TEMPERATURE SENSOR
WHAT SHOULD THE HUMIDITY LEVEL SENSOR BE PLACED
IN THE CONDITIONED SPACED
WHAT TEMPERATURE SENSORS ARE USED WITH A COMMERCAIL AIR HANDLER
MIXED AIR, SUPPLY AIR, AND PREHEATED SENSORS
WHAT DOES THE LOW TEMPERATURE THERMOSTAT DO
WHEN IT SENSES AIR TEMPERATURE BELOW 35*F IT SHUTS DOWN THE BLOWER
AN UNDERSIZED VALVE MAY CAUSE
CAVITATION
IN A DIRECT DIGITAL CONTROL SYSTEM THE PRIMARY CONTROLLER IS THE
HVACR COMPUTER
WHICH CONTROL SYSTEMS ALLOW A BUILDING TO BE MONITORED AND CONTROLLED FROM A REMOTE LOCATION
DIRECT DIGITAL
PNEUMATIC CONTROL SYSTEMS
USE AIR PRESSURE TO MODULATE CONTROL VALVE
A DEVICE THAT CONVERTS A NON ELECTRICAL IMPULSE SUCH AS SOUND, HEAT, LIGHT, OR PRESSURE INTO AN ELECTRICAL SIGNAL IS CALLED
A SENSOR
THE GENERAL TYPES OF COMMERCIAL CONTROL SYSTEMS INCLUDE
ELECTRIC, ELECTRONIC, AND PNEUMATIC
THE PERIMETER OF A LARGE MULTISTORY HIGH-RISE BUILDING CONSIST OF
THE AREA AROUND THE OUTSIDE OF THE BUILDING
IN A SINGLE-ZONE CONSTANT-VOLUME SYSTEM, WHICH FLOORS ONLY HAVE PROVISIONS FOR COOLING
Intermediate floor
WHICH PART OF A LARGE OFFICE BUILDING GENERALLY REQUIRES COOLING ALL YEAR, EVEN WHEN IT IS COLD OUTSIDE
CORE
THE PERIMETER SYSTEM IS OFTEN USED ALONGSIDE A CORE SYSTEM IN
LARGER BUILDINGS
THE CORE OF A LARGE MULTISTORY HIGH-RISE BUILDING CONSISTS OF
THE INTERIOR AREA
A SINGLE-ZONE CONSTANT-AIR-VOLUME SYSTEM IS BEST SUITED FOR CONDITIONING
A BUILDING CORE AREA
IN PERIMETER APPLICATIONS USING THE VARIABLE-AIR-VOLUME SYSTEM, THE PRIMARY AIR HANDLER PROVIDES
VARIABLE VOLUME AND CONSTANT TEMPERATURE
OUTSIDE AIR IS DRAWN INTO THE BUILDING THROUGH
AN OUTSIDE DAMPER
THE AMOUNT OF OUTSIDE AIR INTRODUCED CAN BE CONTROLLED USING
A CO2 SENSOR
HOW DOES AN ENERGY-RECOVER WHEEL IMPROVE SYSTEM EFFICENCY
BY TRANSFERRING HEAT BETWEEN THE VENTILATION AIR AND THE EXHAUST AIR
IN THE EVENT OF AFIRE, FIRE DAMPERS PREVENT OXYGEN FROM FEEDING THE FIRE BY
CLOSING OFF OUTSIDE AIR SUPPLY COMPLETELY
UNDER NORMAL OPERATION, SOME OUTSIDE AIR WILL ALWAYS BE INCLUDED TO
PREVENT EXCESSIVE LEVELS OF CO2 FROM THE BUILDING
WHEN A VAV BOX ON A CONSTANT-AIR-VOLUME SYSTEM THROTTLES AIR INTO THE CONDITIONED AREA
The excess air dumps into the area above the ceiling
A UNIQUE FEATURE OF MULTIZONE AND DOUBLE-DUCT SYSTEMS IS THAT THEY
CAN HEAT AND COOL AT THE SAME TIME USING A SINGLE AIR HANDLER
RESIDENTIAL AIR CONDITIONING REFERS TO AIR CONDITIONING APPLIED TO
PRIVATE HOUSEHOLD RESIDENCES
SEMIHERMETIC COMPRESSORS ON LARGE COMMERCIAL AC USE ______ TO STAGE THE COMPRESSOR BY CUTTING OUT INDIVIDUAL CYLINDERS IN RESPONSE TO LOAD CHANGES
UNLOADERS
COMMERCIAL AIR CONDITIONING REFERS TO AIR-CONDITIONING APPLICATION IN
RETAIL STORES AND BUILDING OFFICE
COIL CORROSION THAT RESULTS FROM TWO DISSIMILAR METALS COMING IN CONTACT WITH AN ELECTROLYTE IS
GALVANIC
PTAC UNITS ARE
PACKAGED TERMINAL AIR-CONDITIONING
WHICH AREA OF A LARGE OFFICE BUILDING HAVE THE MOST CONSTANT COOLING LOAD
THE INTERIOR PART OF THE BUILDING
A SIGNIFICANT CONTRIBUTION TO THE COOLING LOAD FOR THE INTERIOR PORTION OF A COMMERCIAL OFFICE BUILDING IS
THE HEAT GENERATED BY LIGHTING
WHAT DOES HYGROSCOPIC MEANS
A MATERIAL THAT READILY ABSORBS WATER
CONDENSER HEAT RECLAIMING SYSTEMS USED TO CONDITIONED SPACE ARE MOST FREQUENTLY FOUND IN
SUPERMARKETS
WHAT IS A SECONDARY REFRIGERANT
A SECONDARY REFRIGERANT ABSORBS HEAT THROUGH TEMPERATURE CHANGE ONLY
WHAT TYPES OF COMPRESSORS ARE COMMONLY USED FOR LARGE CHILLERS
CENTRIFUGAL AND SCREW
WHAT APPLICATION ARE BEST SUITED FOR CONSOLE THROUGH THE WALL PTAC UNITS
HOTEL AND MOTELS
RESTAURANTS, NIGHTCLUB, AND CASINO APPLICATION ALL REQUIRE
HIGH RATES OF VENTILATION TO EXHAUST ODORS AND FUMES
CHILLED WATER SYSTEMS USE A PRIMARY REFRIGERANT TO REMOVE HEAT FROM THE SECONDARY REFRIGERANT IN A CHILLER UNIT. WHAT IS THE SECONDARY REFRIGERANT IN SUCH SYSTEMS.
WATER
WHAT IS A DX COIL
A DIRECT EXPANSION COIL
WHAT IS THE DIFFERENCE BETWEEN A VISCOUS IMPINGEMENT FILTER AND A STANDARD FILTER
VISCOUS FILTER ARE TREATED WITH A STICKY SUBSTANCE TO TRAP AND HOLD DIRT
THE COMPONENTS OF A COMMERCIAL FAN COIL UNIT INCLUDE
A FAN, A WATER COIL, A FILTER, A FRESH AIR SUPPLY, AND A CONTROL SYSTEM
A CENTRAL STATION AIR-HANDLING UNIT
IS USED FOR LARGE SYSTEMS AND IS ASSEMBLED ON SITE USING SEPARATE COMPONENTS
THE MAJOR COMPONENTS OF AN AIR HANDLING UNIT INCLUDE
FAN AND MOTOR, HEATING AND COOLING COIL, AIR FILTERS, DAMPERS
THE TWO BASIC TYPES OF FANS USED IN MOST AIR-HANDLING UNIT ARE
CENTRIFUGAL AND AXIAL
THE MOST COMMON FAN USED FOR MOVING AIR ACROSS OUTDOOR CONDENSER COILS IN RESIDENTIAL AIR CONDITIONING IS
PROPELLER
THREE TYPES OF FAN BLADES USED WITH CENTRIFUGAL FANS INCLUDE
FORWARD-CURVED, BACKWARD-CURVED, AND BACKWARD-CURVED AIRFOIL
THIS TYPE OF FAN IS COMMONLY USED ON CONDENSER MOTORS BECAUSE IT MOVES HIGH VOLUMES OF AIR IN LOW STATIC CONDITIONS
PROPELLER
IMMEDIATELY AFTER MAKING ADJUSTMENTS TO AN AIR HANDLER IT IS IMPORTANT TO CHECK
THE BLOWER MOTOR AMP DRAW UNDER LOAD
THE AMP DRAW OF A PROPELLER FAN WILL______ IF THE AIRFLOW LEAVING THE BLOWER IS BLOCKED OR RESTRICTED
INCREASE
A TYPE OF FAN THAT IS DESIGNED FOR PRODUCING HIGH STATIC PRESSURE IN DUCT DISTRIBUTION SYSTEMS IS
CENTIFUGAL
THE TWO MAIN TYPES OF FAN DRIVES ARE
DIRECT DRIVE AND BELT DRIVE
WHAT IS A HEPA FILTER
A VERY HIGH EFFICIENCY AIR FILTER
AIRFLOW THROUGH AN AXIAL FAN IS
PARALLEL TO THE FAN SHAFT
Codes related to rooftop installation includes
Uniform Mechanical code, International Mechanical code, and National fuel gas code
what type of blower configuration requires a water-filled P-trap to ensure proper condensate draining?
Draw-through evaporator with blower downstream
The electrical disconnect box for a rooftop unit is
mounted on the unit
Rooftop units should be level when they are installed so that?
the condensate can drain properly
When installing a rooftop package unit, proper airflow through the condenser fan is critical. The minimum free clearance air space above the condenser fan should be.
60 inches
A crucial requirement whenever a rooftop installation is considered is.
To ensure that the roof structure can support the weight of the equipment.
One unique problem with rooftop units installed in a seacoast area is that
Salt spray accelerated corrosion of metallic parts
The gas line should include
A stop valve and a drip leg
The location for a rooftop unit will be partly determined by?
The distance that a crane can reach over the edge of the building.
Proper height above the roof is important when installing a heat pump rooftop unit?
So that snow does not block airflow through the outdoor coil.
The raised, rectangular sheet metal frame that a rooftop unit rests on is called a
Curb
Rooftop units can have the duct work connected to either?
The bottom or the side of a unit
To ensure that the rafters or joists do not interfere with installation of the plenums on a curb-mounted rooftop unit?
The roof curb must be square with the roof joists or rafters.
The condensate drain on a rooftop unit?
Must include a trap unless the unit has an integral trap
Water and air leakage between the rooftop unit and the rooftop curb are prevented by?
Gasket material between the curb and the unit
Which of the following statements regarding chillers are true?
Dry (direct expansion) chillers require less refrigerant than do flooded chillers
In a flooded chiller, the refrigerant
Surrounds tubes filled with chilled water
What is a function of a purge unit?
A purge unit will purge the air from the top of the condenser
When leak testing a low pressure chiller, the pressure should not be allowed to exceed 10 psig to avoid:
Breaking the rupture disk and losing the refrigerant charge
The pressure of a low pressure chiller is raised for leak testing by:
Circulating warm water through the chiller bundle
Which type of compressor chiller uses a pair of rotors to compress the refrigerant gas?
Screw compressor chillers
Traditional methods of capacity control for centrifugal compressors include:
Variable inlet vanes and motor speed control
To avoid freezing the water in the chiller during recovery:
Circulate the chiller water
In order to leak test a low pressure chiller, the chiller pressure:
Must be increased to positive pressure less than 10 psig
Which type of chiller is more likely to freeze the tubes if charged or recovered improperly?
Flooded chillers
What type of compressor is most often used in large chillers?
Centrifugal
In a direct expansion chiller, the chiller water is circulated:
Over the outside of the chiller tube
Compared to centrifugal chillers, screw chillers generally:
Are physically smaller for comparable capacity
When air enters a low pressure system, it collects in the condenser because:
The air will not condense
How should refrigerant be recovered from a chiller?
Always begin the refrigerant recovery using liquid recovery methods
What do modern hydronic systems use to circulate hot water?
Pumps
Compared to air heating systems, hydronic heating systems:
Are normally more expensive to install
What is a hydronic terminal unit?
The coils and devices that heat the building
The different types of terminal units used for hot water heating systems include:
Baseboard heaters, convectors, fan coil units, and radiators
What is a primary way a convector heats a room?
Through natural convection along the outer walls
Balancing valves are required:
To allow adjustable flow
What materials are most commonly used for hydronic piping?
Copper and cross-linked polyethylene
In a series loop system:
All the water flows through each convector loop
Most hydronic heating systems are:
Closed piping systems
What component is used to compensate for different pressure drops and load requirements?
Balancing valves
Mixing valves control the final temperature of radiant loops:
By mixing the hot boiler water with the cooler return water
What happens when the electrical contacts close in the motorized valve?
The circulator pumps starts
Which system heats a room more evenly, leading to fewer cold spots?
Radiant floor heating
A modern hydronic heating system typically:
Heats by circulating hot water through a closed system of piping
What kind of boiler is used for residential installations?
Hot water
What is the difference between a steam boiler and a hot water boiler?
Hot water boiler does not actually boil the water
What is the minimum desired return water temperature for a gas fired boiler?
At least 140 degrees Fahrenheit returning to the boiler
Why is it desirable to have a minimum water temperature entering the boiler?
To prevent condensation in the flue
What is a pickling solution?
A corrosion inhibitor used on steel pipes
What materials are boilers commonly made from?
Most are either cast iron or steel
What is the difference between a fire tube and a water tube boiler?
Water is inside the tubes of a water tube boiler and outside the tubes of a fire tube boiler
What is the purpose of the zinc rod used in steel boilers?
It prevents corrosion by reacting with corrosive elements before they attack the boiler
The highest available output for a water boiler is:
50,000,000 btu
What is the maximum working pressure for a low pressure steam boiler?
15 psi
An expansion tank problem may be indicated by:
A weeping relief valve
How is a hot water boiler pressure relief valve tested?
By lifting the lever located at the top of the relief valve
Why is low water a dangerous condition for a boiler?
A boiler that is low on water can create steam pressure and explode as a result
What is a low water cutout?
It is a safety device that shuts off the boiler if the water level is low
What controls the firing of a water boiler?
An aquastat that senses the temperature of the water in the boiler
Which of the following is not an energy source for small room space heaters?
Nuclear
Why do many building codes restrict the use of unvented gas fired space heaters?
They release all their combustion products into the space they are heating
Where are salamanders used?
They are often used during building construction to supply temporary heat
The three types of gas heaters are:
Vented, unvented, and catalytic
A catalytic space heater differs from other types of gas heaters in that a catalytic space heater:
Has no flame
Why do some gas furnaces not require an electrical power supply?
The gas valve is operated with the voltage generated by the thermopile safety
Which type of electrical space heater has the greatest potential for overheating?
Convection baseboard electric space heaters
Which type of space heater is generally the least expensive to purchase?
Electric space heater
Which type of electric space heater is often used in office and home settings for uniform room temperature control?
Convection baseboard electric space heaters
How do infrared heaters transfer heat?
They directly heat people and objects through radiation
What is the most frequently used type of electric space heater for residential and commercial buildings?
Forced air electric space heaters
The standard wattage rating of electric baseboard heaters is:
250watts per foot
Which type of space heater must be turned on and operating when the space temperature falls below freezing?
Steam space heaters
Which type of space heater would be ideal for the spot removal of ice or snow on your doorstep or patio deck?
Electric infrared space heaters
The application of electric space heaters is generally more flexible than space heaters that rely on combustion because:
They don't require any combustion air and don't require venting