Chapter 6 Flashcards
Which of the following are advantages of a warm air heating system?
A. A more uniform temperature distribution can be obtained due to the positive air circulation.
B. Filters may be used to clean the air.
C. Controlled amounts of external ventilation may be drawn into the system.
D. All of the above.
D
What is the name given to the furnace type that has the return air enter the top and the supply air leave the bottom of the system?
A. Low Boy Furnace
B. Downflow Furnace
C. High Boy Furnace
D. Horizontal Furnace
B
The flue gas temperature on the heat exchanger exit of a warm air furnace is about blank.
A. 150°C, [300°F]
B. 300°C, [570°F]
C. 230°C, [450°F]
D. 365°C, [690°F]
C
High efficency warm air furnaces incorporate:
a)An electric heat exhanger
b)A secondary heat exchanger
c)A secondary fuel source
d)A heat recovery unit
b
The term “space heater” generally applies to a unit that heats the air directly without the use of:
a)Ducting
b)A heat exchanger
c)Steam coils
d)Controls
a
An AFUE (Annual Fuel Utilization Efficiency) of 75% means:
a)75% of the heating value of the fuel burned is transferred to the heating air
b)75% of the heating value of the fuel burned is lost up the stack
c)75% of the heating air is circulated at set point temperature
d)75% of the water content in the flue gases are reclaimed in the secondary heat exchanger
a
The purpose of a secondary warm air heating system is
a)To scrub the heat from the flue gases
b)To provide main heating for comfort
c)To provide noise-dampening for the primary heating system
d)To provide filtered, heated, humidified outside air
d
When the primary source of heat in a building is steam, the ventilating air is often heated by:
a)Direct-fired heat exchangers
b)Electric resistance coils
c)Steam coils
d)Air coils
c
One of the most significant improvements to a furnace’s AFUE (Annual Fuel Utilization Efficiency) comes from the implementation of ________________ into the design.
a)A vent damper
b)An electronic ignition
c)Hydronic coils
d)A secondary heat exchanger
d
The type of direct-fired forced warm air furnace that saves floor space is the:
a)Upflow
b)Crossflow
c)Lowboy
d)Downflow
a
The secondary heat exchanger in a high efficiency direct-fire warm air furnace is made of stainless steel because:
a)Stainless steel is the most conductive heat exchange material
b)The flue gases leave a high temperature
c)The flue gases leave at temperature below the dew point
d)Stainless steel is the most cost effective heat exchanger material
c
n buildings without basements, the upflow direct fired warm air furnace may be installed with no return air ducting provided:
a)The blower is the axial flow type
b)The return air flow is routed through the basement
c)The return passage is fitted with filters
d)The return air flow back to the furnace is unrestricted
d
