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Plumbing Terminology
Extensive Online Plumbing Dictionary

Click on any letter of the term you would like to find

T & C:
Threaded and Coupled. Some cast iron pipe is sold threaded with a coupling attached.

T & P Valve:
A safety device used to expel excess pressure or heat from inside a tank.

T & S:
Tub and Shower.

The portion of a drain fitting which protrudes into the trap.

Tail Pipe:
The pipe added below the jet assembly, in a weak well application.

Fixture reservoir for flush water. On a conventional toilet, the ballcock, flush valve, and trip lever are installed in a tank. A tank lid closes the top tank opening.

Tank Cross:
A double-tee-shaped fitting installed between a shallow well pump and the ballder tank with integrated valve and gauge fittings, and an outlet for a pressure-relief valve.

Tankless Water Heater:
Type of water heater which heats water as it passes through. No storage tank necessary. Also known as "instantaneous heater".

Tannin (Tannic Acid):
A substance occurring naturally in well water. It is produced by decaying vegetation, and causes the water to have a yellow to light brown color and can provide a bitter taste. There is currently no EPA regulatory level for tannin in water.

Tap Adapter:
Fitting with one plain end and one threaded female end.

Tap Tee:
Cast iron tee with a threaded female side inlet.

Tap Water:
Water provided by a water company by way of the homes plumbing system.

Tapered Pipe:
Standard type of threads used on iron pipe and pipe fittings.

Threaded Both Ends.

Trichloroethylene - A degreasing agent used as a solvent for cleaning metal parts. Ingestion of TCE can cause nervouse system effects and cancer.

Total Dissolved Solids.

T-shaped fitting with three openings that allow another pipe to be joined at a 90° angle. Used to create branch lines.

Teflon Tape:
A fluorocarbon polymer with non-sticker properties used to wrap pipe threads to seal joint.

Teflon Tape:
A fluorocarbon polymer with non-sticker properties used to wrap pipe threads to seal joint.

Temperature Rise:
The number of degrees Fahrenheit that incoming water must be raised to reach the desired water temperature.

Tempered Glass:
glass that has been annealed or strengthened by a process of gradually healing and cooling. Once a piece of glass has been tempered, it cannot be cut. If it breaks, it breaks into many small pieces. By code, all shower doors must be made of tempered glass.

Tempering Valve:
An in-line hot/cold mixing valve.

Test Plug:
A rubber plug that is used to seal off sections of pipe to allow testing for leakage.

Test Tee:
A tee with a removable plug for permitting access to a drainage line.

Measurement of 100,000 BTU's.

Thermal Efficiency:
Ability to transfer and absorb heat from fuel sources into the water.

Thermal Expansion:
The effect of water expanding when heated.

Small electric generator. Electron flow between the hot junction of 1200°'F and cold junction of 600°'F creates millivoltage.

Apparatus that consists of a number of thermocouples combined so as to multiply the effect and is used for generating electrical current.

Thermostatic (Lower):
Device which automatically maintains a predetermined temperature in an appliance.

Thermostat (Upper):
Device which automatically maintains a predetermined temperature in an appliance, usually equipped with a safety shutoff.

Thermostatic Valve:
A shower mixing valve with automatic temperature control. When temperature fluctuations occur at the water inlets, a thermal actuator adjusts the hot and cold ratio to maintain the original temperature setting.

Trihalomethanes - Carcinogens caused as a byproduct of water chlorination.

A helical or spiral ridge on a screw, nut, or bolt.

The underside portion of some faucet spouts which also use a top shroud to cover an assembled faucet waterway. The throatplate is only visible when viewed from a very low angle.

Tile Rise (Buttress):
The raised portion of a shower curb that is on more that one level.

Threads Only.

Toilet Bowl:
Water receptor which receives liquid and solid waste.

Total Discharge Head:
The total pressure or head the pump must develop. It is the sum of the depth to pumping level, elevation, service, pressure, and friction loss.

Total Dissolved Solids:
A measure of the total amount of dissolved matter in water.

Total Head:
The difference between the head at the discharge and suction flange of the pump.

Touchless Faucet:
Commercially installed faucet or urinal valve that function using an infrared sensor system.

Toxicity Test:
Test to determine the toxicity of a chemical or an effluent using living organisms. It measures the degree of response of an exposed test organism to a specified chemical or effluent.

Threads Per Inch.

Transite Pipe:
Pipe manufactured from asbestos and concrete, commonly found in water mains.

Transom Panel:
A panel usually located above the door of an enclosure. It can be used to keep steam inside of a steam-shower unit. Some open to vent steam.

Curved section of drain line that prevents sewer odors from escaping into the atmosphere. All fixtures that have drains must have a "P" trap installed. A toilet is the only plumbing fixture with an "S" trap.

Trap Arm:
The waste arm portion of a drainage trap.

Trap Dip:
The U-bend portion of a drainage trap.

Trap Drain:
A flex adapter to connect 1-1/4" to 1-1/2" drain pipe.

Trap Primer:
A small feeder line connecting the cold water line directly to the drainage trap, which releases a small amount of water to the trap should it run dry to maintain the water seal.

Trap Seal:
Height of water in a toilet bowl "at rest". It provides the water seal which prevents sewer gases from entering the home. It is measured from the top of the dam down to the inlet of the trapway. Also referred to as deep seal.

Channel connecting bowl to waste outlet where siphoning action occurs.

Any non-vitreous china toilet components, except the seat. Includes such items as ballcock, bolt caps, & trip lever.

Trip Lever:
Flush handle and actuating arm on a toilet tank. Also the lever that opens and closes the drain on the bathtub waste and overflow.

Tub Spout:
Faucet component which delivers water from the faucet valve to the bath.

Tube Talon:
Plastic hanger for mounting copper pipe.

Tube Valve:
A valve which is opened or closed by mechanically moving a tube upstream or downstream by an actuating screw.

Tube Washer:
Replacement washer for one end of a closet tube.

The process in which blister-like growths of metal oxides develop in pipes as a result of the corrosion of the pipe metal. Iron oxide tubercles often develop over pits in iron or steel pipe, and can seriously restrict the flow of water.

Water cloudiness caused by suspended particles.

Turbulent Flow:
Fluid flow in which the velocity at a given point varies erratically in magnitude and direction.

Two-Piece Toilet:
Toilet with a separate tank and bowl. Also referred to as a close-coupled toilet.

Type "L" Tube:
An industry standard for copper tubing defined by the tube wall thickness and identified by a "blue" strip. The "L" copper tube wall is approximately 50% greater thicken than type "M".

Type "M" Tube:
An industry standard for copper tubing defined by the tub wall thickness and identified by a "red" stripe.

Tyseal Gasket:
Gasket for joining SV cast iron pipe into a hub.