HVAC Practice Exam Questions Correctly
Answered and Updated!!!
What are the types of Automatic Controls? - ANSWER Electrical, Mechanical,
Electromechanical and Electronic.
Describe the Electrical Automatic Controls - ANSWER Operated and normally control
electrical devices.
Describe the Mechanical Automatic Controls - ANSWER Typically operated by pressure
or temp and often control fluid flow.
Describe the Electromechanical Automatic Controls? - ANSWER Driven by pressure or
temperature to provide electrical functions.
Describe the Electronic Automatic Controls - ANSWER Electronic controls use electronic
circuits and devices to perform the same functions that electrical and electromechanical
controls perform.
Automatic control of a system is intended to do what? - ANSWER Maintain stable or
constant conditions with a controllable device.
Thermal Changing Controls, how many are there? - ANSWER One. Thermostat.
What is the function and or use of a thermostat? - ANSWER To maintain desired
temperature in a space or refrigerator system.
What else can a thermostat be used for? - ANSWER A safety device, by protecting
people and equipment from damage by disabling a system if unsafe temp exists.
, Define a Bimetal Device - ANSWER Most common device used to detect thermal change.
What does a bimetal device consist of? - ANSWER Two unlike metal strips with different
rates of expansion and contractions.
What are the types of bimetal devices? - ANSWER Coiled, Wound Helix, Hairpin and
Worm.
Rod and Tube is what kind of device? - ANSWER A bimetal control of two unlike metals,
also referred to a rod-in-tube.
What does the rod and tube do? - ANSWER The tube is inserted into a residential gas or
water heater tank and provides an accurate sensing of the water temperature.
What are the two most common types of metal in a bimetal device? - ANSWER Brass
and Steel.
How does the rod and tube act? - ANSWER Like a piston, contracting when the
temperature is cold and expanding when its hot.
What is a Snap-Disc used for? - ANSWER Mostly a safety. Its a bimetal device that sense
temperature changes. Can be used as a control.
Where do snap discs usually go? - ANSWER Close to the windings. Sometime theyre
imbedded into the windings.
Where are snap discs used always? - ANSWER In controls that start and stop electrical
loads.
Answered and Updated!!!
What are the types of Automatic Controls? - ANSWER Electrical, Mechanical,
Electromechanical and Electronic.
Describe the Electrical Automatic Controls - ANSWER Operated and normally control
electrical devices.
Describe the Mechanical Automatic Controls - ANSWER Typically operated by pressure
or temp and often control fluid flow.
Describe the Electromechanical Automatic Controls? - ANSWER Driven by pressure or
temperature to provide electrical functions.
Describe the Electronic Automatic Controls - ANSWER Electronic controls use electronic
circuits and devices to perform the same functions that electrical and electromechanical
controls perform.
Automatic control of a system is intended to do what? - ANSWER Maintain stable or
constant conditions with a controllable device.
Thermal Changing Controls, how many are there? - ANSWER One. Thermostat.
What is the function and or use of a thermostat? - ANSWER To maintain desired
temperature in a space or refrigerator system.
What else can a thermostat be used for? - ANSWER A safety device, by protecting
people and equipment from damage by disabling a system if unsafe temp exists.
, Define a Bimetal Device - ANSWER Most common device used to detect thermal change.
What does a bimetal device consist of? - ANSWER Two unlike metal strips with different
rates of expansion and contractions.
What are the types of bimetal devices? - ANSWER Coiled, Wound Helix, Hairpin and
Worm.
Rod and Tube is what kind of device? - ANSWER A bimetal control of two unlike metals,
also referred to a rod-in-tube.
What does the rod and tube do? - ANSWER The tube is inserted into a residential gas or
water heater tank and provides an accurate sensing of the water temperature.
What are the two most common types of metal in a bimetal device? - ANSWER Brass
and Steel.
How does the rod and tube act? - ANSWER Like a piston, contracting when the
temperature is cold and expanding when its hot.
What is a Snap-Disc used for? - ANSWER Mostly a safety. Its a bimetal device that sense
temperature changes. Can be used as a control.
Where do snap discs usually go? - ANSWER Close to the windings. Sometime theyre
imbedded into the windings.
Where are snap discs used always? - ANSWER In controls that start and stop electrical
loads.
