Glossary of Plumbing Terms

A.C.	Alternate Current - Electrical supply in which the polarity of the hot wire  reverses rapidly
AGA	American Gas Association
Ambient Temperature	The average temperature of the atmosphere in the vicinity of an  appliance
Ampere	Unit of measure of current flow
Anode Rod	A sacrificial rod composed of one or more metals installed in the  water heater that protects the tank from corrosion helping extend the life of  the tank
Anti Scald Valve	Device used to prevent high water temperature
ASHRAE	American Society of Heating Refrigeration Air Conditioning Engineers
ASME	American Society of Mechanical Engineers
Atmospheric Combustion	takes place when gaseous, liquid or solid fuels react at an  elevated temperature with oxygen by burning, thus releasing heat
Back Flow	When water travels from one system back into any part of the main  distribution system
Boiling Point	The boiling point refers to the temperature at which a liquid  changes to vapor by the addition of heat
BTU	British Thermal Unit - Unit of heat energy required to raise 1 lb. of water 1 degree F
Burner	A heat producing device where the flame or heat is produced
Check Valve	To allow fluid to flow in only one direction in a pipe; also known as back flow preventer
Closed System	A system where the incoming cold water supply has a device that  will not allow water to expand when heated (i.e. check valve, back flow  preventer, some pressure reducing valves)
Combustion Chamber	The location where combustion takes place.
Combustion Gases	Gases released when a gaseous, liquid or solid fuel reacts at an elevated level that needs to be vented with gas or oil-fired water heaters
Commercial Application	Water heaters used for more than a single family dwelling
Condensation	Formed by more heat being absorbed into the water leaving less temperature to carry the water vapor produced in gas combustion to pass out of  the venting system
Conventional Venting	Atmospheric venting that utilizes the natural convective rise of hot flue gases through the system to release the products of  combustion
Cycle	The number of times a second that a conductor carrying A.C.  returns to the same polarity; generally 60 cycle A.C. is supplied
D.C.	Direct Current - Electrical supply in which the polarity of the  two wires does not change
Degree Rise	Difference between the starting water temperature and the ending temperature after heating is complete
Dielectric	A nonconductor of direct electric current
Dip Tube	Tube inside the water heater that sends cold water to the bottom of the tank
Direct Vent	Pulls outside air for combustion and vents combustion gases  directly outside
Draft Diverter	A device fitted in the flue way of a gas appliance to prevent  updraft, downdraft or the secondary flue blockage from obstructing the escape of products of combustion or otherwise affecting the normal operation of the  appliance
Drain Valve	Device designed to allow drainage of stored contents from a water  heater
Dual element heater	An electric water heater with an upper and lower element for heating water
E.C.O.	Energy Cut Off - Safety device designed to shut power off to the water heater and prevent high temperature
EF	Energy Factor - A measure of the overall efficiency rating of the  water heater based on the model's recovery, efficiency, stand-by loss and energy input
Efficiency	A products ability to utilize input energy; expressed as a percentage
Energy Guide Label	The Federal Trade Commission (FTC) requires that gas, electric and oil residential automatic storage water heaters be labeled to show 1.) an  estimated annual cost of operation for that particular model, based on a  national average cost of fuel specified by FTC and 2.) how the efficiency of  that model compares to all other comparable models
Expansion Tank	Designed to absorb excess pressure due to thermal expansion, e.g.  closed system
First Hour Delivery (Rating)	Combination of the usable stored volume of hot water in tank,  plus the recovery capacity for the first hour of operation
Flow control valve	Device designed to reduce water flow (GPM) to a plumbing fixture (i.e. shower head at 5 GPM vs. 2.5 GPM); the use of flow control valves can be  cost effective in load calculations, reducing the water usage and the amount of energy used to heat water
Flow rate	Rating in gallons per minute (GPM) or gallons per hour (GPH)
Flue	A passage way for products of combustion
Flue Baffle	A device to deflect, check or regulate flow through the  flue
Flue Damper	Minimizes convective heat loss through venting system
Foam Insulation	The insulation surrounding the surface of the water heater tank
Foot Print	The area of space taken up by the water heater
Galvanic Action	If two unlike metals are immersed in an electrolyte, an  electrical potential will exist between them; if the two are in electrical contact, an electrical current will flow; the metal which becomes the anode of this cell will corrode and dissolve while the cathode will be protected from corrosion
GAMA	Gas Appliance Manufacturers Association
Gas Control	Device use to regulate gas pressure on a water heater
Glass Lining	See Vitraglas®
Hard Water	Natural waters contain impurities in various proportions;  traditionally hardness is a measure of calcium or dissolved solids in a  solution. Below is a list of types of hardness and their referenced parts per million range Type Hardness Soft 0-49 ppm Fairly soft 50-99 ppm Fairly hard 100-149 ppm Hard 150-249 ppm Very Hard 250 plus
Head LOSS	The pressure of water as measured at a stated point; it may be measured in feet or in pounds per square inch (PSI)
Heat Exchanger	A heat transfer system
Heat Transfer	When heat is passed from one medium to another
Heat Trap	Restricts heat loss through water connections to a tank
Hertz	A measure of frequency; one Hertz equals one cycle per second; 60  cycle A.C. is 60 hertz A.C.
Hydrojet®	Cold inlet tube designed to reduce sediment build-up and increase  efficiency in the water heater
Immersion	Referring to something submerged in water
Incoming (Inlet) Temperature	Temperature of water entering the tank
Input	The amount of fuel used by a water heater in a given period of time: generally rated in 1 houR
Instantaneous Water Heater	A type of water heater that heats water as it flows through a  heat exchanger coil
ISO 9000	A series of five standards for developing a total quality  management system. Developed by the International Organization for  Standardization based in Geneva, Switzerland
Jetport	Referring to the Hydrojet dip tube. Creates turbulence in the  tank
Junction Box	Utility area where incoming current is connected in a water  heater
KW - kilowatt	A measure of the rate of supply of energy or power, and is equal to 1000 watts or 3412 BTU per hour
Laminar Flow	Streamline flow in a fluid near a solid boundary
Life Cycle Labs	A place where water heaters are tested at an accelerated rate to simulate life expectancies
Light Duty	Small commercial applications
LP	Liquid Propane - A fuel for gas water heaters
Manifolded Installation	Paralleling of water heaters for large hot water demand  applications
Millivolt	One thousandth of a volt
Mixing Valve	Mixes hot and cold water to achieve a specified delivery temperature
Natural Gas	A fuel used with gas water heaters
Net Usable BTU	That portion of a fuel's heat energy actually transferred into the water by the heater
Non-CFC	Foam insulation that minimizes the use of Chlorofluorocarbons
NSF	National Sanitation Foundation
OHM	A unit of electrical resistance
Oil Powered	A water heater that uses oil as its fuel source
Operating cost	The cost of running a water heater for a given time  period
Parallel System	Two or more identical size heaters piped with water connections, that is, cold water travels equal distance into the inlets of the heaters from a "t" connection and hot water travels equal distance from the outlet of the  heaters to a "t" connection
Peak Hour Demand	Time when the largest demand for hot water is needed
Peak Load Period	That period of the day when the system has the greatest demand
Phase	For ease of production and distribution, A.C. is distributed in  what is known as 3 phase supply using three active wires and one neutral  wire
Pilot	A small burner used to ignite the main burner
Point of use	Small water heater used for remote locations water heater
Power Venting	Mechanical draft exhaust to outside, usually utilizing room air  to support combustion
Preheated water	Water that has been tempered for inlet supply
Pressure Reducing Valve	A valve which automatically reduces inlet water pressure to a  specified value at its outlet under static cold water conditions
Rated Storage Volume	Quantity of water (expressed in gallons) stored in a tank
Recovery (GPH)	The amount of water in gallons that can be heated in one hour
Residential	Water heaters for single family dwellings
Return Circulation System	Tempered water from or near the point of usage which eliminates  waste of hot water used for long runs and adds storage to the system
RF	Recovery Factor - Rating based on the efficiency of the product  which is input required to raise 1 gallon of water 1 degree F Gas - 75% to 85% RF = 11 to 9.7 BTU/H Electric - 100% RF = .0024 KW/H Oil - 70% to 85% RF = 11.79 to 9.7 BTU/H
Safety shut off valve	A device on a gas appliance which shuts off the gas supply to the  appliance to prevent a hazardous situation. A flame failure safety shut off operates when the actuating flame becomes extinguished. A 100% shut off cuts off all gas including main and pilot burners
Scale	A thin coating or layer, usually calcium on the bottom of a tank or interior parts, that may prevent heat transfer
Sealed Combustion	Sealing of combustion chamber to prevent spillage of combustion  products
Sediment (lime)	The substance that settles on the bottom of a tank
Series SYSTEM	Generally where the primary heater preheats water to a given desired general purpose temperature and feeds into another heater
Sight Hole	Generally referring to oil-powered product that allows the viewing of burner and flame patterns
Sliding Inner Door	A door slides along combustion chamber radius for easy access to the burner and pilot
Solenoid	A coil of wire in the form of a cylinder that when carries a current; resembles a bar magnet
Spark Ignition	Intermittent ignition device that utilizes a spark to light a  flame
Spark Test	A test procedure to evaluate the integrity of the glass  lining
Spud	A threaded opening on the water heater tank
Stacking	The ability of hot water to form layers of different temperatures  in the tank; stratification
Stand By Loss	The amount of heat lost while unit is in stand by mode
Standing pilot	See pilot
Storage Tank	A tank used to hold a specific volume of water
Surface Mount	Usually referring to thermostats mounted on the outside of the tank which senses temperature through the steel tank
T & P Valve	Temperature & Pressure Relief Valve - A safety device used to  expel excess pressure or temperature from inside a tank
Tankless Water Heater	Commonly known as instantaneous
Temperature Rise	The number of degrees fahrenheit (F) the incoming cold water must  be raised to reach the desired hot water temperature
Therm	A measurement of 100,000 BTU's
Thermal Efficiency	Ability to transfer and absorb heat from fuel source into the  water
Thermal Expansion	Water, a non-compressible liquid, expands when heated
Thermal Stratification	See stacking
Thermocouple	A small electric generator. Electron flow between the hot  junction of 1200 degrees F and the cold junction of 600 degrees F creates millivoltage
Thermopile	An apparatus that consists of a number of thermocouples combined as so to multiply the effect and is used for generating electric current
Thermostat Lower	A device which automatically maintains a predetermined temperature in an appliance
Thermostat Upper	A device which automatically maintains a predetermined temperature in an appliance usually equipped with a safety shut off
Turbulent Flow	A fluid flow in which the velocity at a given point varies erratically in magnitude and direction
UL	Underwriters Laboratories
UltracoilTM	A true double wall heat exchanger
Usable Storage	The percentage of hot water that can be drawn from a tank before the temperature drops to a point that is no longer considered hot
Vacuum	Recommended for installation on all side (bottom) cold inlet heaters;
Relief Valve (anti-siphon)	prevents internal vacuum conditions that could drain a system by back siphonage, eliminates burned out electric elements and collapsed  tanks
Venting Materials	Materials used for venting; i.e. PVC, CPVC, ABS, metal
Vitraglas®	Trademark of glass lining for Bradford White Tanks
Volt	Unit of measurement of electromotive force
Waterway Fitting	A channel through which water can flow; connects water heater to inlet & outlet lines
Water Hammer	A concussion or sound of concussion of moving water against the  side of a containing pipe or vessel
Watt	A unit of electrical energy or power; one ampere x one volt = one  watt
Watt Density	Amount of watts concentrated per square inch of element blade  surface area
Working Pressure	Maximum pressure of the operating system permissible
Yearly Cost	The cost of operating a water heater for a year