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TERM
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EXPLANATION
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HBA |
Home Builders Association
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HD |
Head |
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HP |
Horsepower |
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HT |
Hose Threads. Note: Garden
hose threads are different from standard pipe threads. |
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HVAC |
Heating, Ventilation, and
Air Conditioning. |
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Hand-shower |
A showerhead designed with a handle that's
connected to a water supply and a flexible hose. |
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Hanger |
A device used to support pipes.
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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. |
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Hardness |
The amount of dissolved minerals in water
measured in grains per gallon (GPG). The most common minerals are calcium
and magnesium. |
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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). |
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Head |
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. |
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Head Loss |
The pressure of water as measured at a stated
point, either in feet or in pounds per square inch (PSI). |
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Heat Exchanger |
A heat transfer system. |
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Heat Sensors |
Heat-triggered devices on sprinkler systems
that release the flow of water. |
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Heat Trap |
Restriction of heat loss through water connections
to a tank. |
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Hermetic |
Completely sealed, especially against the
escape or entry of air. |
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Hold Down |
A type of pipe anchor consisting of a U-strap
bolted at either end onto a horizontal plate. |
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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. |
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Horizontal Branch |
Lateral drain pipes that run from plumbing
fixtures to the waste stack in a building or in the soil. |
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Horizontal Run |
The horizontal distance between the point
where fluid enters a pipe and the point at which it leaves.
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Hose Bibb
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An outdoor faucet, also used to supply washing
machines. |
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House Trap |
U-shaped fitting with two adjacent cleanout
plugs visible at floor level if main drain runs under floor.
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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. |
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Hydration |
The chemical absorption of water into a substance.
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Hydraulic Pressure |
Pressure that exists in a system containing
non-compressible liquid. |
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Hydrolysis |
The reaction of a salt with water to form
an acid and a base. |
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Hydronic |
System of forced hot water. |
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Hydrojet |
Cold inlet tube designed to reduce sediment
build-up and increase efficiency in a water heater. |
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Hydro Jetting (Service) |
The process of clearing blocked pipes using
high pressure water as a boring and flushing mechanism. More on
Hydro
Jetting Service |
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Hydrostatic Pressure |
Pressure exerted by or existing within a liquid
at rest with respect to adjacent bodies |
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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. |
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Hypochlorite |
The OCL anion; calcium and sodium hypochlorite
are commonly used as bleaches and disinfecting agents. |
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