| HP |
 |
Horsepower |
| HVAC |
|
Heating, Ventilation, and Air Conditioning |
| Handles |
|
Faucet handles typically come in 3 styles: knob, lever, and cross. Some manufacturers allow a customer to mix and match components to create a custom handle consisting of handle bases and handle inserts. |
| Handshower |
|
A showerhead designed with a handle that's connected to a water supply and a flexible hose. |
| Hanger |
|
A device used to support pipes. |
Hard Water |
|
Natural water containing impurities in various proportions. Traditional hardness is a measure of calcium or dissolved solids in a solution, measured in parts per million. Hard water generally ranges from 100 to 250 ppm. |
| Hardness |
|
The amount of dissolved minerals in water measured in grains per gallon (GPG). The most common minerals are calcium and magnesium. |
| Hardness Leakage |
|
The presence of a consistent concentration of hardness in the effluent from an ion exchange water softener, often due to high concentrations of hardness or sodium in the water being treated (see Leakage). |
| Head / HD |
|
(1) The pressure of water (or steam) in a closed system (see Pressure Head). It represents the differential in the gravitational force exerted by a liquid at two different depths.
(2) Nautical slang term for toilet |
| Head Loss |
|
The pressure of water as measured at a stated point, either in feet or in pounds per square inch (PSI). |
| Heat Exchanger |
|
A heat transfer system |
| Heat Sensors |
|
Heat-triggered devices on sprinkler systems that release the flow of water. |
| Heat Trap |
|
Restriction of heat loss through water connections to a tank. |
| Hermetic |
|
Completely sealed, especially against the escape or entry of air. |
| Hex Key |
|
Allen Wrench |
| Hold Down |
|
A type of pipe anchor consisting of a U-strap bolted at either end onto a horizontal plate. |
| Hole Saw |
|
A small, cylindrical attachment for a power drill consisting of a circular saw blade for cutting holes. |
| Hollow-jet Valve |
|
A valve having a closing member that moves upstream to shut off the flow. The hollow-jet valve discharges a hollow or annular jet dispersed over a wide area. |
| Horizontal Branch |
|
Lateral drain pipes that run from plumbing fixtures to the waste stack in a building or in the soil. |
| Horizontal Rum |
|
The horizontal distance between the point where fluid enters a pipe and the point at which it leaves. |
| Hose Bibb |
|
An outdoor faucet, also used to supply washing machines. |
| House Trap |
|
U-shaped fitting with two adjacent cleanout plugs visible at floor level if main drain runs under floor. |
| Hub & Spigot Piping |
|
Gravity rated DWV or pressure pipe that has a bell-shaped section at one end and a straight section at the other. As lengths are assembled, the straight end of one fits into the bell of the next. |
| Hubless |
|
Same as no-hub. Cast iron drainage pipe with neoprene gaskets and clamps. |
| Hydraulic Pressure |
|
Pressure that exists in a system containing non-compressible liquid. |
| Hydrolysis |
|
The reaction of a salt with water to form an acid and a base. |
| Hydronic |
|
System of forced hot water. |
| Hydrojet |
|
Cold inlet tube designed to reduce sediment build-up and increase efficiency in a water heater. |
| Hydro Jetting (Service) |
|
The process of clearing blocked pipes using high pressure water as a boring and flushing mechanism. |
| Hydrostatic Pressure |
|
Pressure exerted by or existing within a liquid at rest with respect to adjacent bodies. |
| Hydrostatic Test |
|
Test using non-compressible liquid under pressure at a level equal to or greater than the maximum pressure that will be utilized when in use, such as in steam boilers. |
| Hydrous |
|
Containing water, water of crystallization or hydration, as certain minerals or chemical compounds. |
| Hygroscopic |
|
Attracting or absorbing moisture from the air; changed or altered by this absorption. |
| Hypochlorite |
|
The OCL anion; calcium and sodium hypochlorite are commonly used as bleaches and disinfecting agents. |
