Property & Building Inspection · Task 9 of 19

Mechanical exhaust study notes

Fans, dryer vents and the fixtures they serve.

Key points

• Dryer duct: smooth metal, no screws protruding into the airflow, damper, no screen, length limited by the manufacturer.
• Bath fans need ducting to the exterior with a damper; insulate ducts in cold attics.
• Kitchen hoods that recirculate don't remove moisture; vented hoods should exhaust outdoors.
• Fixtures: operate them, check flow and drainage, and look for leaks, loose toilets, failed grout and caulk.
• Whirlpool tubs need GFCI and pump access; fill above the jets before running.
• Hot on the left at faucets; dishwashers need an air gap or high loop.

Exam tip

plastic or foil dryer ducts are a fire hazard.

Practise this task

Try free mechanical exhaust practice questions with answers and explanations, or look up terms in the glossary.

These notes are an original study aid and may contain errors. Verify against current IRC, NEC and NFPA editions and your state's standards of practice.