REVIEWQUESTIONS
1.
What category of furnace is the
90 Plus gas furnace?
t
a. Category I
b. Category II
C. Category Ill
d. Category IV
2.
What is the correct manifold gas
pressure needed to operate this
furnace on natural gas?
a.
3.5"w.c.
b. 10.0" w.c.
C.
14.0" w.c.
d.
3.5 psi.
3.
Use an Ohmmeter to determine
if the limit switch is open or
closed. A zero (0) Ohm reading
indicates an open limit.
a. True
b. False
4.
Which of the following is a
correct method to determine if
the indoor air flow is correct?
a. clocking the gas meter
•
b. measuring the flue gas
temperature
C.
measuring the temperature
rise
d.
measuring the incoming line
voltage
5.
What is a possible cause for
the over temperature switch
opening?
a. too little gas pressure
b. reversed line voltage polarity
c. restricted combustion air
piping
d. too little CFM from the indoor
blower
6. Which test instrument is used to
check the make point of the
negative pressure switches?
a. U-tube manometer
b. microamp meter
c. voltmeter
d. Magnehelic gauge
,,
7. Which item monitors the
presence of flame at the
burners?
a. Hot surface igniter
b. sensor rod
c. thermocouple
d. pressure switch
8.
What should happen if the main
limit opens?
a. The furnace control board
immediately locks out the
furnace;
b. The main blower runs until
the limit resets;
C. Both the main blower and
induced draft blower run until
the limit resets;
d. The unit immediately retries
for ignition.
9.
What could cause the furnace
control board to lock out
the unit?
a. Reversed polarity of line
voltage power
b. very low gas pressure
c. disconnected igniter wire
d. all of the above
10. The signal telling the furnace
control board the presence of
flame is measured in:
a. DC millivolts,
b.
DC microamps,
C. DC volts,
d. DC amps.
11. What is a possible cause for a
high carbon monoxide reading in
the flue gases?
a. oversized combustion air
intake pipe,
b. too high a CFM from the
indoor blower,
c. excessive gas pressure,
d. a dirty filter.
12.
What is the minimum line
pressure for LP gas
installations?
a. 5" w.c.
b. 10"
w.c.
C. 11"
w.c.
d.
14"
w.c.
13. How is the indoor blower off
delay timing set?
a. Set the off temperature on
the furnace fan control;
b. Adjust the setting screws on
the furnace control board;
C.
The board automatically
shuts off the blower after 120
seconds;
d. Adjust the setting DIP
switches on the furnace
control board.
14.
Where do unused blower motor
speed wires attach?
a. On furnace control board
terminals marked
"M1"
and "M2";
b.
On furnace control board
terminals marked "FAN";
C.
Wire nut or tape them out of
the way;
d.
On furnace control board
terminals marked
"HEAT'
and"COOL".
15.
What is the correct sequence of
furnace operation with OSI?
a. Induced draft fan, OSI
activation, pressure switch
closing, gas valve opens;
b. Induced draft fan, OSI
activation, gas valve opens,
pressure switch closes;
c.
DSl activation, induced draft
fan, pressure switch closes,
gas valve opens;
d. Induced draft fan, pressure
switch closes, OSI activation,
gas valve opens.
16.
When twinning two 90 Plus
furnaces together, both boards
must be identical.
a. True
b. False
17.
What is the induced draft fan
prepurge cycle time length?
a. 10 seconds
b. 30 seconds
C. 60 seconds
d.
depends on the setting of the
furnace control board
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