NH Journeyman Plumber key terms

An unobstructed vertical distance through free atmosphere between the lowest opening of a water supply outlet and the flood-level rim of the receiving fixture or receptacle. It is the strongest form of backflow protection.

A device or assembly installed to stop reverse flow of water caused by backpressure or backsiphonage. Common types include reduced-pressure-zone assemblies, double check valves, and vacuum breakers.

Any actual or potential link between a potable water supply and a source of contamination or pollution. Such connections must be eliminated or protected by an approved backflow device.

A device that admits air into a piping system when internal pressure drops below atmospheric, breaking a siphon. Atmospheric and pressure-type styles are used on hose bibbs, flush valves, and similar outlets.

The edge of a fixture or receptacle from which water would overflow onto the floor. It establishes the reference point for air gaps, fixture outlet heights, and backwater valve settings.

The level at which water would begin to overflow a fixture, receptor, or drain opening. Drainage and venting requirements are referenced to this level rather than to the fixture bottom.

A dimensionless measure of the probable load a plumbing fixture places on the drainage or water supply system, based on its discharge rate and use frequency. Values are summed to size pipes.

The load value assigned to a fixture for sizing the building drain, branches, and stacks. One unit is roughly equivalent to the discharge of a lavatory at one cubic foot per minute.

A value expressing a fixture's probable demand on the potable water distribution system, accounting for flow rate and how often it is used. Values are converted to gallons per minute for sizing.

The lowest piping of a drainage system that receives waste from inside the building and conveys it to the building sewer. It extends to a point about two feet outside the building wall.

The pipe carrying sewage from the end of the building drain to the public sewer, private disposal system, or other point of disposal. It begins outside the building foundation.

A vertical drainage pipe that carries the discharge of water closets and, often, other fixtures to the building drain. It must extend through the roof or connect to a vent header.

The extension of a soil or waste stack above the highest fixture branch, carried to open air. It provides relief for the stack and is not the same as a separate vent stack.

A vertical vent pipe installed primarily to provide air circulation to a drainage system and to relieve pressure in stacks. It connects vent branches and terminates in open air.

A pipe that vents a single fixture trap directly to a vent stack or branch. It protects the trap seal by equalizing pressure on both sides of the trap.

A single vent pipe serving two fixture traps, typically installed on fixtures set back to back or side by side on the same floor. The connection must meet height and spacing limits.

The water retained in a fixture trap that blocks sewer gas from entering the building. Its depth is measured between the crown weir and the dip of the trap.

The portion of a fixture drain between the trap weir and the vent fitting or the point where it connects to a vented branch. Its length and slope are limited to prevent siphonage.

The total measured run of pipe along its centerline, including fittings and changes of direction, rather than straight-line distance. It is used for sizing gas piping and evaluating vent and trap arm limits.

A safety device that opens to discharge excess temperature or pressure from a storage water heater. It must be piped to a safe discharge point with no valve or reduction between heater and termination.

The increase in water volume as it is heated, which raises pressure in a closed system. A thermal expansion tank or an approved relief arrangement is needed to control it.

The passage that carries combustion products from a gas-fired water heater to the outdoors. It must be properly sized, pitched, and connected to a listed venting system.

A device on a gas appliance that draws dilution air and stabilizes draft through the flue, preventing downdraft and spillage of combustion products into the space.

The air supplied to a fuel-burning appliance for proper burning of gas. It must be provided from outdoors or from adequately sized indoor volumes to prevent incomplete combustion.

Selecting pipe diameter based on the appliance input in Btu per hour, the developed length of the run, and allowable pressure drop. Undersized pipe causes low pressure and poor appliance performance.

A dirt pocket installed at the bottom of a gas piping drop to collect debris and condensate before gas enters the appliance controls. It is required at each appliance connection.

A device or arrangement that absorbs pressure surges in water piping caused by rapid valve closure. Water hammer arrestors are the common manufactured form.

A loud banging or pounding in water piping produced by a pressure surge when flow stops abruptly. It can damage joints and fixtures and is controlled with arrestors or slower-closing valves.

The fall of a horizontal drainage pipe expressed as inches per foot. Proper slope carries solids and liquids without leaving waste behind or allowing water to outrun solids.

An accessible opening in a drainage system that allows a drain-cleaning tool to be inserted. Cleanouts are required at the base of stacks, at changes in direction, and at intervals in long runs.

A trap installed on the building sewer near the foundation to keep sewer gas from entering the building drain. Many codes restrict or prohibit it when a public sewer is used.

The piping system that collects and conveys rainwater and surface water from roofs, yards, and paved areas. It must be kept separate from sanitary drainage unless combined systems are permitted.

A pipe that carries rainwater from a roof drain or gutter to a storm drain, catch basin, or other point of disposal. Leaders are sized by roof area and rainfall intensity.

The pipe connecting one or more fixtures to a soil or waste stack or to a branch drain. It carries the fixture discharge and must be vented as required.

The pipe bringing potable water from the public main or private source to the building. It is sized for demand and protected against freezing and backflow.

The New Hampshire state board that administers plumber licensing, approves examinations, and enforces the plumbing rules. Candidates should know its role in licensure and discipline.

A credential allowing a plumber to perform plumbing work under the supervision required by state rules. Eligibility typically involves documented experience and passing an examination.

Written authorization from the local authority to install, alter, or repair plumbing work. Permits trigger inspections and must be obtained before work begins.

The inspection of piping, vents, and connections performed after installation but before fixtures and walls conceal the work. Approval is required before covering the installation.