CBD Plumbing & Fixture Integration 3 — Questions and Answers
Question 1: A thermostatic shower valve differs from a pressure-balance valve in that it also:
- Shuts off water when pressure drops below a set point
- Maintains a preset temperature even when flow rate changes (Correct answer)
- Requires no mixing of hot and cold water
- Is only rated for single-function shower heads
Correct answer: Maintains a preset temperature even when flow rate changes
Thermostatic valves maintain the user's preset temperature by automatically adjusting the hot/cold mix ratio regardless of supply pressure or temperature fluctuations.
Question 2: Which toilet rough-in dimension is most common in US residential construction?
- 10 inches
- 12 inches (Correct answer)
- 14 inches
- 16 inches
Correct answer: 12 inches
The 12-inch rough-in (from finished wall to center of drain) is the most common standard in US residential bathrooms.
Question 3: For a wall-hung toilet, the in-wall carrier system must be designed to support a minimum static load of:
- 200 lbs
- 400 lbs (Correct answer)
- 500 lbs
- 750 lbs
Correct answer: 400 lbs
Most in-wall carrier systems for wall-hung toilets are rated to support a minimum of 400 lbs static load to meet safety standards.
Question 4: A body spray system in a custom shower requires multiple valve outlets. The designer should specify a:
- Single thermostatic valve with multiple volume control ports
- Separate pressure-balance valve for each body spray
- Manifold system connected to a master thermostatic valve (Correct answer)
- Standard two-handle faucet with splitter adapters
Correct answer: Manifold system connected to a master thermostatic valve
A manifold system connected to a master thermostatic valve allows individual volume control for each body spray while maintaining consistent temperature.
Question 5: When installing a rain shower head in the ceiling, the supply line rough-in is typically located:
- 8 inches above finished ceiling
- Inside the ceiling cavity, with a drop ell brought to finished ceiling level (Correct answer)
- On the nearest wall at 80 inches AFF
- Through a floor chase from below
Correct answer: Inside the ceiling cavity, with a drop ell brought to finished ceiling level
Ceiling-mounted rain heads require supply piping run through the ceiling cavity with a drop ell positioned to finish flush with the ceiling surface.
Question 6: The purpose of an air admittance valve (AAV) in bathroom plumbing is to:
- Regulate water pressure at fixtures
- Allow air into the drain system to prevent siphoning without a traditional vent stack (Correct answer)
- Filter air from the hot water supply line
- Provide emergency shutoff for the drain
Correct answer: Allow air into the drain system to prevent siphoning without a traditional vent stack
An AAV is a one-way mechanical vent that opens to admit air when negative pressure occurs in the drain, preventing trap siphoning without extending the vent stack through the roof.
Question 7: When a bathroom remodel changes the toilet location by more than 6 inches from the existing drain, the designer must consider:
- Only the new supply line routing
- Opening the floor or wall to relocate and re-slope the drain line (Correct answer)
- Adding a macerating toilet to avoid drain relocation
- Simply adding a drain extension fitting
Correct answer: Opening the floor or wall to relocate and re-slope the drain line
Moving a toilet drain more than a few inches typically requires opening the floor to properly re-route and maintain the required 1/4 inch per foot slope to the main stack.
CBD Plumbing & Fixture Integration 3
A thermostatic shower valve differs from a pressure-balance valve in that it also: