Plumbing Fixtures & Appliances 2 — Questions and Answers
Question 1: What is the purpose of a garbage disposal air gap on a dishwasher drain connection?
- To provide ventilation for the disposal motor
- To prevent dishwasher drain water from backflowing into the dishwasher (Correct answer)
- To allow air into the drain for faster drainage
- To measure water usage
Correct answer: To prevent dishwasher drain water from backflowing into the dishwasher
The dishwasher drain air gap (or high loop) prevents dirty drain water in the sink from backflowing into the dishwasher through the drain hose.
Question 2: What is the minimum clearance required in front of a toilet per the IPC?
- 12 inches
- 18 inches
- 21 inches (Correct answer)
- 30 inches
Correct answer: 21 inches
The IPC requires a minimum clearance of 21 inches in front of a water closet (toilet) to allow for use and maintenance.
Question 3: What type of faucet valve uses a rotating ceramic disc to control water flow?
- Compression valve
- Ball valve faucet
- Cartridge valve
- Ceramic disc valve (Correct answer)
Correct answer: Ceramic disc valve
A ceramic disc valve uses two precisely mated ceramic discs that rotate against each other to control flow and temperature, offering long life and precise control.
Question 4: What safety feature is required on a tub/shower valve to prevent scalding?
- Pressure balancing valve or thermostatic mixing valve (Correct answer)
- Backflow preventer
- Vacuum breaker
- Check valve
Correct answer: Pressure balancing valve or thermostatic mixing valve
A pressure-balancing or thermostatic mixing valve is required on tub/shower controls to prevent scalding when a toilet is flushed or another fixture is used simultaneously.
Question 5: What is the purpose of a wax ring when installing a toilet?
- To level the toilet on uneven floors
- To create a watertight seal between the toilet horn and the floor flange (Correct answer)
- To anchor the toilet to the subfloor
- To provide a gasket for the water supply connection
Correct answer: To create a watertight seal between the toilet horn and the floor flange
The wax ring creates a watertight and airtight seal between the toilet's horn (outlet) and the floor flange, preventing waste leakage and sewer gas entry.
Question 6: What is 'rough-in plumbing'?
- Temporary plumbing installed during construction
- The installation of supply and drain pipes before walls and floors are finished (Correct answer)
- Plumbing installed without permits
- The initial flushing of new pipe systems
Correct answer: The installation of supply and drain pipes before walls and floors are finished
Rough-in plumbing refers to the installation of supply and drain/vent pipes during the framing stage, before walls, ceilings, and floors are closed in.
Plumbing Fixtures & Appliances 2
What is the purpose of a garbage disposal air gap on a dishwasher drain connection?