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