Heating and cooling support tech
Which safety feature could prevent the operation of a gas furnace
Door switch
Flexible duct should be supported at the manufacturer's recommended intervals but should be supported at intervals no greater than how many feet ?
4 feet
What is one sixth of twenty four ?
4
What tool is specifically made to thread a hole in metal
Tap
When using acetylene 15 psig is :
the maximum safe operating pressure
How many inches is the on center spacing of 2 x 4 load bearing wall studs used in residential construction ?
16 inches
Electronic air cleaners could have a maximum output voltage of
5,000 volts or more
Please find the answer to : ( 18+ 9 ) x 2 = ?
54
Residential new construction fall protection is required whenever working over what minimum height
6 ft .
A cylinder of refrigerant is priced at 111.1 How much will seven cylinders of this refrigerant cost ?
778.26
If the trend continues what reading would the technician expect at 4:00 PM °
78.5
What is the plate at the bottom of a wall to which the studs are attached called
A foundation plate
temperature 1 ° F is called added to one pound of water to raise its What is the amount of heat that must be
A Btu
What does the term ' continuity ' indicate
A complete electrical path
What is a Ground Fault Circuit Interrupter ( GFCI
A device that is used to protect against electrical shocks
When two objects A and B ) are in direct contact with each other heat will flow from A to B if :
A has a higher temperature than B.
Which of the following statements is true of a recovery machine
A recovery machine removes refrigerant without testing its purity
What is the primary difference between a grille and a register
A register is equipped with an air volume control device and a grille is not
What is a supply plenum
A section of ductwork at which supply air is available for distribution
Which of the following would cause a heat pump system to short cycle
A system that is oversized for the load
The manufacturer's instruction sheet specifies 0.5 ounces of refrigerant to be added for each added foot of refrigerant line length How much refrigerant must be added to the system for 10 additional feet of line set
A. 5 ounces
What is the effect on supply airflow when the size of the return duct is decreased
Airflow will be decreased
What is electrical current measured in ?
Amperes
tool for cutting the opening in a metal Which of the following is the recommended . cabinet
Aviation snips
Where would an electronic air cleaner be installed in a residential forced - air system ?
B. On the return air side
What is an exposed central support that runs parallel to the ceiling called
Beam
two drives to connect two sections of duct What should a technician do after inserting together
Bend the ends of the drives over the duct
Where should the liquid line filter - drier be located ?
Between the condenser and TEV
flux with a silver brazing alloy ? Which of the following requires the use of
Brazing copper to brass
What is the purpose of a nitrogen purge when brazing piping
Interior oxides are prevented from forming
Which of the following is a likely problem if a heat pump has a high indoor temperature rise ?
Clogged expansion valve
What is the process of heat transfer by which gases and liquids move due to changes in temperature and / or pressure called ?
Convection
Which of the following is true of a DC circuit
Current flows in one direction in a DC circuit
What can short cycling an A / C system result in ?
Decreased humidity control
What happens to heat pump capacity in heating mode as outdoor temperature decreases ?
Decreases
What happens when air moves too quickly through a filter ?
Decreases filtration
What is a possible cause of poor performance in an air conditioner ?
Dirty filters
Which of the following describes the image below ?
Double " s" slip
What is a duct transition
Duct fitting that connects two ductal sections of different size or shape
What should be done prior to connecting the line voltage wiring to an indoor air handler or furnace
Ensure the supply power is off
What is a device used to charge a system with a specified number of ounces of refrigerant
Electronic charging scale
A loose control voltage connection can cause which of the following problems
Erratic operation
Why is operating sound a consideration in the location of a condensing unit
Excessive noise could be disruptive to the customer
What can an undersized electrical conductor under load result in
Excessive wire temperature
What is a critical step when installing the gauges on a unit ?
Front - seat the gauge valves
How can you promote safety on any new job site ?
Having regular job safety briefings
What can cause sweating windows and mildew on walls and furniture ?
High humidity
What is a benefit of using an electronic air cleaner ?
Indoor air quality IAQ ) may be improved
What can a dirty or clogged air filter in an operating air conditioning system cause
Inadequate cooling
What could be caused by dirty condenser coils ?
Increase in head pressure
What will be the effect of a cross break made on all sides of any rectangular section of metal
Increased rigidity and reduced vibration
What does a heavily loaded vehicle require ?
Increased stopping distance
Which of the following is an advantage of an infrared thermometer
It measures temperatures in hard to reach areas
Why should oxygen NOT be used as a purging gas ?
It supports combustion
What is the addition or removal of heat without a change in temperature known as
Latent heat
What can be caused by a loose line voltage connection
Melted connection
Why should hacksaws never be used to cut copper tubing
Metal chips can remain inside the tubing
accurate deep evacuation procedure What is one instrument required for an
Micron gauge
What is a digital manifold gauge set useful for
More accurate and improved diagnostics
Which of the following is an effective method for reducing the sound transmissions from an air handler installed in a closet
Mount the cabinet on an isolation pad
What will the voltage across a switch be when the contacts are closed ?
OV
Drive cleats are typically installed where on rectangular duct
On all four sides
How can a technician test the calibration of an anolog manifold
Opening both gauges to the atmosphere and setting the gauges to 0 psig
What tool should be used to remove a sweat type filter - drier from a system
Oxy - acetylene torch
What is a property of using an oxy - acetylene compared to an air acetylene system
Oxy acetylene systems generate higher flame temperatures
What is the primary purpose for using turning vanes in a rectangular elbow ?
Reduce pressure loss and evenly distribute airflow
What is one effect of tighter home and building construction ?
Reduced air infiltration for ventilation
which of the following is an electrical load
Relay coil R
Most tubing cutters have a reamer blade mounted on them What is this blade used for ?
Removing burrs from the inside of tubing after cutting
The R ' value indicates the ability of insulation to do what
Resist heat flow
Which of the following would be used to information to a technician convey hazardous materials and treatment
Safety Data Sheets SDS
What should an installer do when reconnecting sections of round metal duct ?
Secure the pieces together with screws in new locations and seal
What steps are necessary to clean a stacked condenser coil ?
Separate the two rows of coils spray all surfaces with a proper coil cleaner , and water flush
Which of the following is the correct method for cleaning an air distribution blower wheel
Stiff wire brush
What do the gauges on oxy - acetylene torch regulators display ? remaining
Tank pressure and regulator outlet pressure of each gas
What is one reason for using a brazing alloy rather than soft solder when joining copper to copper
The brazing alloy is stronger
What must be prevented when bending soft copper tubing
The diameter of the tube must not be significantly reduced
When the adjustment handle on a manual damper lies parallel to the airflow path of the ductwork , which of the following statements is true
The damper is fully open
What is the primary reason the oil must be changed often in a vacuum pump
The oil absorbs moisture from the system
How many feet above a flat roof must a ladder extend when used to access the roof
Three Feet
Where must the secondary condensate drain of an attic mounted horizontal air handler used with a heat pump be connected
To a location where any condensate water flow can be seen by the occupants
Why are humidifiers used with heating systems
To raise relative humidity and increase customer comfort
What do ceiling joists typically rest directly on ?
Wall top plates
What is power measured in ?
Watts
What should a technician do when working with sheet metal ?
Wear gloves and safety glasses
Whenever nitrogen is used for purging the technician must always be certain : least
a regulator is used on the nitrogen cylinder
When flaring copper tubing with too muchdow starting height , the flare will
be too large for the flare nut
What is oxidation
different A chemical reaction that always involves oxygen
How can a 4 inch pleated filter affect air quality compared to a 1 inch fiberglass filter
reduced dust and allergen levels the
A loose fan belt will :
slip on its pulley
What is the purpose of using flux when soldering
heat flow Reducing oxidation
What is a common cause of noise complaints
high air velocity
What effect will slowing the evaporator fan have on moisture removal
increased moisture removal
should not be inhaled as they : Refrigerant vapors in high concentrations
may cause heart irregularities or unconsciousness .
Electronic air cleaners do NOT remove
odors
When locating flexible duct in a crawlspace the duct should be
suspended from the floor joists
Moisture within a structure flows from
wet to dry