G3 Combustion and Venting Principles 2

Question 1

What is the primary purpose of a draft hood on a gas appliance?

Accepted Answer

To provide a safety break preventing excessive draft and backdraft

Answer

To increase efficiency

Answer

To filter combustion air

Answer

To regulate gas pressure

Question 2

What is a Category I venting system?

Accepted Answer

Negative pressure with non-condensing flue gases

Answer

Positive pressure with condensing flue gases

Answer

A direct-vent sealed system

Answer

A common vent for multiple appliances

Question 3

Why must vent connectors slope upward from appliance to chimney?

Accepted Answer

To ensure proper draft and prevent condensate pooling

Answer

To reduce noise

Answer

To increase gas flow

Answer

To allow thermal expansion

Question 4

What happens when flue gases cool below the dew point in a non-condensing vent?

Accepted Answer

Condensation forms, potentially causing corrosion and failure

Answer

Appliance shuts down automatically

Answer

Draft increases significantly

Answer

Gas pressure drops

Question 5

What is the purpose of combustion air openings in a furnace room?

Accepted Answer

To supply oxygen for proper combustion and draft

Answer

To provide breathing air

Answer

To cool the furnace room

Answer

To allow maintenance access

Question 6

What is spillage in a gas appliance vent system?

Accepted Answer

Flue gases escaping from the draft hood into the room

Answer

Gas leaking from piping

Answer

Water from a condensing furnace

Answer

Excess gas past the valve