G2 GAS TECHNICIAN MODULE 22 REVISED TEST
QUESTIONS AND 100% VERIFIED ANSWERS
At sea level, what force does atmospheric pressure apply to the earth?
ANSWER 14.74 psia
Which two conditions need you to introduce combustion air? ANSWER 1. You
must bring in combustion air if the appliance's total BTU exceeds 400,000.
2. You also need to bring in air if the house is tightly constructed.
What is the upper limit of flue gases that a natural draft system should have?
Why? The maximum temperature is 450 F due to safety concerns about high
heat in a flammable building and the fact that the system becomes less efficient
the hotter the gases go.
What is the ideal minimum temperature for flue gas? Why? ANSWER Because
flue gasses are extremely acidic, they will condense at temperatures higher than
127 F, which can cause corrosion.
What are the functions of special venting systems? ANSWER They are utilized
with condensing or very efficient furnaces. To return additional heat to the
building, they condense the exhaust gases. When one pound of water vapor is
converted to liquid, the latent heat will return 970 btu to the structure.
What is the purpose of direct venting? Direct external supply of combustion air
and direct external release of exhaust gases are provided by ANSWER.
What does a positive vent pressure system look like? A system that isn't
positive? ANSWER Positive: High-efficiency furnace
Natural draft, non-positive
What is determined by flue loss? If the appliance is a condensing system, then
the answer is yes.
A type A vent is what? ANSWER They are steel or masonry chimneys.
QUESTIONS AND 100% VERIFIED ANSWERS
At sea level, what force does atmospheric pressure apply to the earth?
ANSWER 14.74 psia
Which two conditions need you to introduce combustion air? ANSWER 1. You
must bring in combustion air if the appliance's total BTU exceeds 400,000.
2. You also need to bring in air if the house is tightly constructed.
What is the upper limit of flue gases that a natural draft system should have?
Why? The maximum temperature is 450 F due to safety concerns about high
heat in a flammable building and the fact that the system becomes less efficient
the hotter the gases go.
What is the ideal minimum temperature for flue gas? Why? ANSWER Because
flue gasses are extremely acidic, they will condense at temperatures higher than
127 F, which can cause corrosion.
What are the functions of special venting systems? ANSWER They are utilized
with condensing or very efficient furnaces. To return additional heat to the
building, they condense the exhaust gases. When one pound of water vapor is
converted to liquid, the latent heat will return 970 btu to the structure.
What is the purpose of direct venting? Direct external supply of combustion air
and direct external release of exhaust gases are provided by ANSWER.
What does a positive vent pressure system look like? A system that isn't
positive? ANSWER Positive: High-efficiency furnace
Natural draft, non-positive
What is determined by flue loss? If the appliance is a condensing system, then
the answer is yes.
A type A vent is what? ANSWER They are steel or masonry chimneys.
