1 | Page
MN Boiler license Questions and Answers
What is the unit called that controls starting and stopping of the
burner by sensing temperature of water in a hot water boiler?
Ans: Aquastat
What controls the temperature of the water in a hot water boiler
system?
Ans: Aquastat or remote temperature monitoring system
What safety devices should be installed on a hot water heating
boiler?
Ans: Code safety valve(s)
Low water fuel cutoff
What removes air from a hot water boiler system?
Ans: Air control
What valve can be manually opened to provide hot water to the
heating units through natural circulation should a circulating
pump fail?
Ans: Flow control valves
What unit turns the burner on and off based on steam pressure?
Ans: Pressure control or pressurestat
What should be the range of a pressure gauge installed on a steam
boiler?
Ans: At least 1 1/2 times the MAWP of the boiler
What is the definition of absolute pressure?
© 2025 All rights reserved
, 2 | Page
Ans: Gauge pressure plus 14.7
What is it called when a safety valve rapidly opens and closes?
Ans: Chattering
What causes furnace explosions?
Ans: A build up of combustible gasses or vapors in the furnace
How are furnace explosions prevented?
Ans: Purging
What malfunctioning component could cause steam on a steam
boiler system to blow into the vacuum pump or condensate tank?
Ans: Steam trap
What unit shuts off the burner in the event of a low water
condition?
Ans: Low water fuel cut off
What is used to replace water lost by blowing down or to leaks in
the system in a steam boiler system?
Ans: Makeup water
What area of the boiler is used to calculate heating surface?
Ans: The steam space where evaporation takes place
Name two methods by which a steam pressure gauge can be
tested for accuracy.
Ans: Comparison to a test gauge
Calibrate with a deadweight tester
What is the definition of one boiler horsepower?
© 2025 All rights reserved
, 3 | Page
Ans: The evaporation of 34.5 lbs of water per hour from and at a
temperature of 212F
What are the cross-sectional area requirements for a discharge
pipe installed on a safety valve?
Ans: No less than the full area of the valve outlet
On a one pipe steam heating boiler system, what is used to
distribute steam and to return condensate?
Ans: The same pipe
Where is the water on a fire tube boiler?
Ans: Surrounds the tubes
When two valves are used on the bottom blowdown line of a
steam boiler, what valve is located closest to the boiler shell?
Ans: Quick opening valve
How is the capacity of a safety valve used on a steam boiler
measured?
Ans: The amount of steam that can be discharged in one hour
In a steam boiler system, how is condensate removed from the
heating equipment?
Ans: Steam trap
Should pressure control fail, what is installed as a safety backup?
Ans: High limit control
How does the pressure control attached to the steam space of a
boiler control the burner?
Ans: Burner starts on pressure decrease, stops on pressure increase
What is the purpose of a safety valve on a steam boiler?
© 2025 All rights reserved
MN Boiler license Questions and Answers
What is the unit called that controls starting and stopping of the
burner by sensing temperature of water in a hot water boiler?
Ans: Aquastat
What controls the temperature of the water in a hot water boiler
system?
Ans: Aquastat or remote temperature monitoring system
What safety devices should be installed on a hot water heating
boiler?
Ans: Code safety valve(s)
Low water fuel cutoff
What removes air from a hot water boiler system?
Ans: Air control
What valve can be manually opened to provide hot water to the
heating units through natural circulation should a circulating
pump fail?
Ans: Flow control valves
What unit turns the burner on and off based on steam pressure?
Ans: Pressure control or pressurestat
What should be the range of a pressure gauge installed on a steam
boiler?
Ans: At least 1 1/2 times the MAWP of the boiler
What is the definition of absolute pressure?
© 2025 All rights reserved
, 2 | Page
Ans: Gauge pressure plus 14.7
What is it called when a safety valve rapidly opens and closes?
Ans: Chattering
What causes furnace explosions?
Ans: A build up of combustible gasses or vapors in the furnace
How are furnace explosions prevented?
Ans: Purging
What malfunctioning component could cause steam on a steam
boiler system to blow into the vacuum pump or condensate tank?
Ans: Steam trap
What unit shuts off the burner in the event of a low water
condition?
Ans: Low water fuel cut off
What is used to replace water lost by blowing down or to leaks in
the system in a steam boiler system?
Ans: Makeup water
What area of the boiler is used to calculate heating surface?
Ans: The steam space where evaporation takes place
Name two methods by which a steam pressure gauge can be
tested for accuracy.
Ans: Comparison to a test gauge
Calibrate with a deadweight tester
What is the definition of one boiler horsepower?
© 2025 All rights reserved
, 3 | Page
Ans: The evaporation of 34.5 lbs of water per hour from and at a
temperature of 212F
What are the cross-sectional area requirements for a discharge
pipe installed on a safety valve?
Ans: No less than the full area of the valve outlet
On a one pipe steam heating boiler system, what is used to
distribute steam and to return condensate?
Ans: The same pipe
Where is the water on a fire tube boiler?
Ans: Surrounds the tubes
When two valves are used on the bottom blowdown line of a
steam boiler, what valve is located closest to the boiler shell?
Ans: Quick opening valve
How is the capacity of a safety valve used on a steam boiler
measured?
Ans: The amount of steam that can be discharged in one hour
In a steam boiler system, how is condensate removed from the
heating equipment?
Ans: Steam trap
Should pressure control fail, what is installed as a safety backup?
Ans: High limit control
How does the pressure control attached to the steam space of a
boiler control the burner?
Ans: Burner starts on pressure decrease, stops on pressure increase
What is the purpose of a safety valve on a steam boiler?
© 2025 All rights reserved
