🔍 Key Concepts

• Function of an air register in a boiler or furnace system • How air flow to the burner is started, stopped, and adjusted • Difference between controlling temperature vs controlling volume and direction of air

💭 Think About

• Ask yourself: what does an air register actually do in relation to the burner flame—does it heat the air, move it, or control how much passes through? • Which part of the register would logically be responsible for starting/stopping the air flow itself? • Look at each choice and decide: which describes a basic mechanical action of doors, and which describe more specialized functions?

✅ Before You Answer

• Verify which component in a burner system is primarily responsible for heating air (if any) versus just delivering it. • Consider that movable doors usually perform an open/close or throttling function—how does that apply here? • Eliminate any option that describes a task clearly performed by a different piece of equipment (like the fan or structural supports).