A furnace with an AFUE range of approximately 79% to 83% is a ____ gas furnace.

A(n) ____ draft regulator opens when pulled open by the negative pressure of flue gas suction.

A(n) ____ can open and close a gas valve, control a spark or hot-surface igniter, and monitor interlocks.

Which type of furnace takes in return air from the top and forces it out near the bottom?

Which of the following statements regarding hot-surface ignition (HSI) systems is false?

An ignition system that burns and monitors its pilot light only while the thermostat is calling for heat is a(n) ____.

What type of furnaces are high efficiency with AFUE ratings above 90%?

Which of the following statements regarding rollout switches is true?

If the air pressure inside a building is lower than the air pressure outside the building, air will leak in. This is known as air ____.

A humidifier’s water feed should be tapped into the ____.