Unit 22 - Chapter 100 Flashcards
A major disadvantage of an electric resistance cool furnace for warm air heating is
The high cost of electricity
In a warm air heating system the cold air return registers are located
In interior locations
Lowboy furnaces are just
1.2 m in height
The advantage of having duct furnaces instead of a large central furnace is
Better control of heat in each zone of the building
The power supply for an electric resistance cool furnace is
240 V
In a fin coil heat exchanger the primary source for the exchanger is
Steam or hot water
A type of directly fired space heater is
- a unit heater
- a floor furnace
- a wall furnace
High efficiency furnaces and heaters range in annual fuel utilization efficiency from
80 - 95%
In high efficiency furnaces if the temperature of the flue gas drops below 65’C the
Water vapour will condense
In a pulse combination furnace the stated efficiency is
94 - 98%
Which is not a type of heat exchanger used in forced warm air heating systems?
Glycol heater
What is not an advantage of a forced air heating system?
Blower noise can be carried through the ducts
In a pulse burner, the pulse combustion process occurs about ___ to ___ times per second
60, 70
The lowboy furnace is used where
Headroom is limited
Horizontal furnaces are only about
0.6 m high and used where there is limited headroom
Horizontal furnaces are installed
Where headroom is limited such as in attics or crawl spaces or suspended from the ceiling
Downflow furnaces are used in
Buildings without basements
Heating systems with duct furnaces have the advantage that
They can easily match the varying heat demand of the different zones of a building
Electric resistance furnaces are much more compact because
The large heat exchange section as well as the combustion equipment has been eliminated
Elements in electric resistance coils are protected from overheating due to airflow by
A high temperature limit control
Increases in furnace efficiency can be achieve by
Installing a vent damper, electronic ignition, and improved heat exchanger design
A fired heater which is installed on location where eat is needed and heats the air directly without the use of any ducting is
A unit heater (as well as a floor and wall furnace)
Forced warm air heating systems are used more extensively to hear residences since
Installation and maintenance costs are lower
One of the biggest heat losses in warm air furnaces and space heaters is
High temperature of flue gases
In high efficiency furnaces, if the temperature of the flue gas drops below 65’C, the
Water vapour will condense
In a fin coil heat exchanger, the heat exchanger is
A steam or hot water coil
In high efficiency furnace or heaters the temperature of the flue gases are ___ in the secondary heat exchangers
Below the dew point
One of the advantages of forced warm air heating systems is
That controlled amounts of ventilation air can be admitted
Electronic ignition raises efficiency to
78%
One of the disadvantages of forced warm air heating systems is the
Systems can be noisy
