OBT3 FINAL PAPER EXAM 2026 PRACTICE
SOLUTION TESTED QUESTIONS AND
ANSWERS GRADED A+
●● Combustion formula:
a. useful heat energy / chemical heat energy of the fuel efficiency
b. heating energy in the combustion gases / chemical heat energy of the
fuel
c. steady-state heat transfer to heated medium / steady-state chemical
heat energy of the fuel
d. useful heat transfer under standardized conditions / chemical heat
energy of the fuel. Answer: b. heating energy in the combustion gases /
chemical heat energy of the fuel
●● heating system efficiency formula:
a. useful heat energy / chemical heat energy of the fuel efficiency
b. heating energy in the combustion gases / chemical heat energy of the
fuel
c. steady-state heat transfer to heated medium / steady-state chemical
heat energy of the fuel
d. useful heat transfer under standardized conditions / chemical heat
energy of the fuel. Answer: a. useful heat energy / chemical heat energy
of the fuel efficiency
,●● seasonal energy efficiency formula:
a. useful heat energy / chemical heat energy of the fuel efficiency
b. heating energy in the combustion gases / chemical heat energy of the
fuel
c. steady-state heat transfer to heated medium / steady-state chemical
heat energy of the fuel
d. useful heat transfer under standardized conditions / chemical heat
energy of the fuel. Answer: d. useful heat transfer under standardized
conditions / chemical heat energy of the fuel
●● steady-state efficiency formula:
a. useful heat energy / chemical heat energy of the fuel efficiency
b. heating energy in the combustion gases / chemical heat energy of the
fuel
c. steady-state heat transfer to heated medium / steady-state chemical
heat energy of the fuel
d. useful heat transfer under standardized conditions / chemical heat
energy of the fuel. Answer: c. steady-state heat transfer to heated
medium / steady-state chemical heat energy of the fuel
●● On cycle heat loss exists through the flue gases
true
false. Answer: true
, ●● off-cycle heat loss leaves through the __________ (vent or flue gas).
Answer: vent
●● to determine steady-state efficiency, what two measurements of the
flue gases must be taken?. Answer: net stack temp & co2 or CO
●● in the combustion process, as excess air is increased the %co2 by
volume increases
true
false. Answer: false, excess air increases the co volume. excess air cools
the flame , causing incomplete combustion resulting in more CO
●● in the combustion process, as excess air increases the flue gas
temperature increases.
true
false. Answer: true, excess air increases the flow rate of the flue gases so
the heat exchanger doesn't absorb as much heat resulting in the flue
gases leaving the appliance hotter
●● in the combustion process, as excess air is increased the smoke level
increases
true
false. Answer: false, excess decreases smoke levels.
SOLUTION TESTED QUESTIONS AND
ANSWERS GRADED A+
●● Combustion formula:
a. useful heat energy / chemical heat energy of the fuel efficiency
b. heating energy in the combustion gases / chemical heat energy of the
fuel
c. steady-state heat transfer to heated medium / steady-state chemical
heat energy of the fuel
d. useful heat transfer under standardized conditions / chemical heat
energy of the fuel. Answer: b. heating energy in the combustion gases /
chemical heat energy of the fuel
●● heating system efficiency formula:
a. useful heat energy / chemical heat energy of the fuel efficiency
b. heating energy in the combustion gases / chemical heat energy of the
fuel
c. steady-state heat transfer to heated medium / steady-state chemical
heat energy of the fuel
d. useful heat transfer under standardized conditions / chemical heat
energy of the fuel. Answer: a. useful heat energy / chemical heat energy
of the fuel efficiency
,●● seasonal energy efficiency formula:
a. useful heat energy / chemical heat energy of the fuel efficiency
b. heating energy in the combustion gases / chemical heat energy of the
fuel
c. steady-state heat transfer to heated medium / steady-state chemical
heat energy of the fuel
d. useful heat transfer under standardized conditions / chemical heat
energy of the fuel. Answer: d. useful heat transfer under standardized
conditions / chemical heat energy of the fuel
●● steady-state efficiency formula:
a. useful heat energy / chemical heat energy of the fuel efficiency
b. heating energy in the combustion gases / chemical heat energy of the
fuel
c. steady-state heat transfer to heated medium / steady-state chemical
heat energy of the fuel
d. useful heat transfer under standardized conditions / chemical heat
energy of the fuel. Answer: c. steady-state heat transfer to heated
medium / steady-state chemical heat energy of the fuel
●● On cycle heat loss exists through the flue gases
true
false. Answer: true
, ●● off-cycle heat loss leaves through the __________ (vent or flue gas).
Answer: vent
●● to determine steady-state efficiency, what two measurements of the
flue gases must be taken?. Answer: net stack temp & co2 or CO
●● in the combustion process, as excess air is increased the %co2 by
volume increases
true
false. Answer: false, excess air increases the co volume. excess air cools
the flame , causing incomplete combustion resulting in more CO
●● in the combustion process, as excess air increases the flue gas
temperature increases.
true
false. Answer: true, excess air increases the flow rate of the flue gases so
the heat exchanger doesn't absorb as much heat resulting in the flue
gases leaving the appliance hotter
●● in the combustion process, as excess air is increased the smoke level
increases
true
false. Answer: false, excess decreases smoke levels.
