Technical glossary

Looking for a bit more information? Need a technical reference? We've got you covered. Use our glossary to find exactly what you're looking for.

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Glossary: A

AC (Alternating Current)

An electric current that reverses directions at regularly occurring intervals.

AMP (Ampere)

A unit of flow of electrical current.

OHM'S LAW:

For three phase A.C. circuits

Armature

The rotating part of a motor or the moving part of a contactor or relay.

Glossary: B

Bimetal

Two dissimilar types of metal fastened together, when heated they bend which can open or close a circuit.

Bleed Gas

A small flow of gas that assists a diaphragm of a bleed gas valve to operate.

Boiler Horsepower

One boiler horsepower equals 33,475 BTU/HR

Booster

An electric, gas or steam hot water booster for a commercial dishwasher that will supply 180 degrees F minimum rinse water. Formula to size an electric booster.

G.P.H. / 10 = KW based on 40 degrees F temperature rise.

BTU (British Thermal Unit)

The heat required to raise the temperature of one pound of water by one degree Fahrenheit. One BTU per minute = 17.58 watts.

Bypass

A small passageway machined in a valve to allow gas or water to bypass around a closed valve.

Glossary: C

Capacitor

An electrical device to store electrical energy, block the flow of dc current, and to act as a conductor of AC current.

Capillary

A hollow tube used to allow a liquid or gas to flow in a temperature control.

Centigrade Temperature

Metric system scale, 0 degrees being the freezing point and 100 degrees being the boiling point of water. Degrees centigrade =.555 (degrees Fahrenheit -32)

Centigrade	Fahrenheit	Centigrade	Fahrenheit	Centigrade	Fahrenheit	Centigrade	Fahrenheit	Centigrade	Fahrenheit
-50	-58	50	122	150	302	250	482	350	662
-45	-49	55	131	155	311	255	491	355	671
-40	-40	60	140	160	320	260	500	360	680
-35	-31	65	149	165	329	265	509	365	689
-30	-22	70	158	170	338	270	518	370	698
-25	-13	75	167	175	347	275	527	375	707
-20	-4	80	176	180	356	280	536	380	716
-15	5	85	185	185	365	285	545	390	734
-10	14	90	194	190	374	290	554	390	734
-5	23	95	203	195	383	295	563	395	743
0	32	100	212	200	392	300	572	400	752
5	41	105	221	205	401	305	581	405	761
10	50	110	230	210	410	310	590	410	770
15	59	115	239	215	419	315	599	415	779
20	68	120	248	220	428	320	608	420	788
25	77	125	257	225	437	325	617	425	797
30	86	130	266	230	446	330	626	430	806
35	95	135	275	235	455	335	635	435	815
40	104	140	284	240	464	340	644	440	824
45	113	145	293	245	473	345	653	445	833

CFM (Cubic Feet per Minute)

Measurement of air volume by an air handling device.

Combination Gas Valve

A control valve that consists of some or all of the following: manual valve, automatic safety shutoff, main actuator valve, pressure regulator and pilot adjuster.

Contactor

An electromagnetic actuated relay used to close an electrical circuit

Continuity

A continuous path for the flow of electricity.

Current

The flow of electricity, measured in amperes.

Glossary: D

D.C.(Direct Current)

A steady flow of electrical current in one direction only.

Diastat

Part of a thermostat consisting of a sensing bulb, hollow capillary tube and a bellows. This sealed system is filled with a fluid which expands when heated to actuate electrical contacts.

Differential

The difference between the on and off temperatures of an operating thermostat.

Direct Spark Ignition

Two high voltage electrodes create a continuous spark to ignite a main burner.

Disposer

Master disposer replacement work sheet.

D.P. (Double Pole)

A switch device that opens or closes connections in two conductors of the same circuit.

D.P.D.T (Double Pole, Double Throw)

A switch that opens or closes connections alternately in two conductors of the same circuit.

D.P.S.T. (Double Pole, Single Throw)

A switch that opens or closes connections at one position in two conductors of the same circuit.

Glossary: E

ECO

Energy Cut-Off Device

Glossary: F

Fahrenheit

Temperature scale, 32 °F being the freezing point and 212 °F being the boiling point of water.

Degrees Fahrenheit = (1.8 x °Centigrade) + 32

Centigrade	Fahrenheit	Centigrade	Fahrenheit	Centigrade	Fahrenheit	Centigrade	Fahrenheit	Centigrade	Fahrenheit
-50	-58	50	122	150	302	250	482	350	662
-45	-49	55	131	155	311	255	491	355	671
-40	-40	60	140	160	320	260	500	360	680
-35	-31	65	149	165	329	265	509	365	689
-30	-22	70	158	170	338	270	518	370	698
-25	-13	75	167	175	347	275	527	375	707
-20	-4	80	176	180	356	280	536	380	716
-15	5	85	185	185	365	285	545	390	734
-10	14	90	194	190	374	290	554	390	734
-5	23	95	203	195	383	295	563	395	743
0	32	100	212	200	392	300	572	400	752
5	41	105	221	205	401	305	581	405	761
10	50	110	230	210	410	310	590	410	770
15	59	115	239	215	419	315	599	415	779
20	68	120	248	220	428	320	608	420	788
25	77	125	257	225	437	325	617	425	797
30	86	130	266	230	446	330	626	430	806
35	95	135	275	235	455	335	635	435	815
40	104	140	284	240	464	340	644	440	824
45	113	145	293	245	473	345	653	445	833

Field Coil

A coil of insulated wire wrapped around an iron core. When electric current flows through the coil, a magnetic field is produced. Used in motors in conjunction with an armature.

Glossary: G

Gas Orifice Capacity Chart (BTU Ratings)

Glow Coil

A coil of fine wire which when heated by an electrical current glows and is used to light a pilot flame.

GPH (Gallons Per Hour)

The measurement of the flow of a volume of liquid. To convert GPH to GPM divide by 60.

GPM

Gallons Per Minute

Glossary: H

Hot Surface Ignition

A resistive element is used to heat and ignite a gas burner.

Hp (horsepower)

One horsepower = 2544 B.T.U. per HR.

One horsepower = 745.2 watts

Horsepower	=	KW
3		5
5		5
7.5		7
10		9.5
15		12.5
20		15.5
25		18

HZ (Hertz)

Frequency of ac power in cycles per second. Usually 60 HZ in USA and 50 HZ overseas.

Glossary: I

ID

Internal Diameter

Inches of Water Column

A measurement of gas pressure, one inch of water column equals 0.036 psi. 28 inches of water column equals 1 psi.

Infrared Burner

Heat is produced by a glowing burner surface which radiates infrared energy.

Intermittent Pilot Ignition

Pilot flame ignites only when main gas burner is to be ignited.

IPS

Iron Pipe Size

Glossary: J

Jet Burner

A burner in which gas and air mixtures combine in air above the burner ports to burn.

Glossary: K

KPA (Kilopascal)

Metric pressure measurement.

kW (Kilowatt)

One kW equals 1,000 watts.

kWh (Kilowatt Hour)

The amount of energy one kilowatt produces in one hour. One kilowatt hour = 3412 Btu Per hour.

Glossary: L

Line Voltage

The voltage level of the main power supply.

Load

Electrical power consumed by components of an electrical circuit.

LPG (Liquefied Petroleum Gas)

Referred to as propane.

Glossary: M

Manometer

Instrument for the measure of gas pressure in inches of water column.

Milliamp

1 /1000 of an ampere.

Millivolt

1 /1000 of a volt

Mini-Pilot

A thermocouple and pilot combines in one device.

Glossary: N

Natural Gas

Gas extracted from the earth.

N.C.

Normally Closed

A switch or other device which is in the closed position when not energized or activated.

N.O.

Normally Open

A switch or other device which is in the open position when not energized or activated.

Glossary: O

OD

Outside Diameter

OHM

The resistance which will allow one ampere of current to flow when the voltage is one Volt.

Ohm's Law

Equations of relationship of voltage, current, and resistance.

Equations of Relationships of Voltage, Current and Resistance

Common Equations Derived from OHM'S LAW:

REMEMBER:

• I = AMPS: Measures Current
• E = VOLTS: Measures Electrical Force
• R = OHMS: Measures Resistance to Electric Current
• W = WATTS: Electric Power or Heat Energy

If elements are designed for 3-PHASE DELTA connection, wattage output may be reduced to 1/3 by reconnecting to 3-PHASE WYE

FOR CURRENT IN 3-PHASE CIRCUITS

Ohm's Law Calculation Examples

Ohm's Law Calculation Examples

Open Circuit

An electrical circuit through which a current can not flow because of an open switch or other break in the wiring.

Glossary: P

Parallel Circuit

An electrical circuit in which more than one path is provided for the current flow.

Pilot Safety Valve

A valve of which closes when pilot flame does not exist, valve automatically stops the flow of gas to the pilot and main burners.

Pipe Sizes

Dimensions of standard pipe.

Nominal Pipe Size	Threads per Inch	Inside Diameter Inches	Outside Diameter Inches
1/8"	27	.269	.405
1/4"	18	.364	.540
3/8"	18	.493	.675
1/2"	14	.622	.840
3/4"	14	.824	1.050
1"	11-1/2	1.049	1.315
1-1/4"	11-1/2	1.380	1.660
1-1/2"	11-1/2	1.610	1.900
2"	11-1/2	2.067	2.375
2-1/2"	8	2.469	2.875

Pressure Drop

The decrease in gas pressure as gas passes through a control or piping.

Primary Side of Transformer

The high voltage side of a step-down transformer.

PRV (Pressure Reducing Valve)

A mechanical valve that reduces the incoming pressure of air, water or steam to a Lower set pressure.

PSI

Pounds Per Square Inch

PSIG

Pounds Per Square Inch Gauge

Glossary: R

Relay

An electromagnet device used in a control circuit to provide electric current to a valve or switch. Referred to as a start relay when used for a motor.

Resistor

A device to limit the current flow in a circuit.

Rheostat

A type of resistor where the resistance can be adjusted to various levels.

Glossary: S

Safety Pilot Valve

See pilot safety valve.

Secondary Transformer Winding

Low voltage side of a step down transformer.

Series Circuit

An electrical circuit in which only one continuous path is provided for the flow of current, so that the current flows through all components in the circuit.

Solenoid

A wire wound coil that creates a magnetic field when energized.

Solenoid Valve

A valve operated by a solenoid coil.

Solid-state

Semiconductor type switching device with no moving parts to control an electrical circuit.

S.P. (Single Pole)

A switch device that opens or closes connections in a single conductor.

S.P.D.T.

Single Pole, Double Throw

A switch that opens or closes connections at one position in a circuit.

S.P.S.T

Single Pole, Single Throw

A switch that opens or closes connections at one position in a circuit.

Standing Pilot

Pilot flame remains lit whether main burner is off or on.

Steam Temperature/Pressure Table

Gauge Pressure P.S.I.G.	Temperature Fahrenheit
0	212
2	218.5
4	224.4
6	229.8
8	234.6
10	239
15	249.7
25	266.8
30	274
40	286.7
50	297.7

Glossary: T

Therm

100,000 BTU's

Thermal Overload Protector

A device which trips an internal switch to interrupt electrical current to protect against an over current condition.

Thermocouple

A device containing two different metals which produces a small amount of DC voltage when heated. Operates a pilot safety valve.

Thermopile

A group of thermocouples contained in one unit, when heated by a pilot flame millivolts are generated to energize a pilot safety valve or power a millivolt operated control.

Thermostat

An automatic device actuated by temperature changes to control a preset operating temperature.

Transformer

A device for changing one voltage to another voltage.

Tubing Sizes

Type K and L Copper Water Tubing

Nominal Size Inches	Actual Outside Diameter Inches
1/4	3/8
3/8	1/2
1/2	5/8
3/4	7/8
1	1-1/8
1-1/4	1-3/8
1-1/2	1-5/8
2	2-1/8

Two-Stage Pilot

A pilot ignition system that uses a small standing pilot flame to light a larger pilot.

Glossary: V

Vac

Volts Of Alternating Current

Vacuum

A pressure lower than atmospheric pressure.

VDC

Volts Of Direct Current

Venturi

A piece of pipe that attaches to a burner. Because it narrows down then flares out it Increases gas velocity to create a negative pressure for combustion.

Volt

One volt will produce a flow of one ampere through a one OHM resistance. OHM'S LAW

VOLTS = AMPERAGE x OHMS

Voltage

The force of electric current through a circuit.

Glossary: W

Water

• One gallon of water = 8.34 lbs.
• One Cubic Foot of Water = 62.4lbs.
• One Cubic Foot of Water = 7.38 gallons.
• One gallon of water = 231 cubic inches.
• One BTU = The quantity of heat to raise the temperature of one pound of water 1 degree between 32 degrees and 212 degrees °F

Kilowatt Heating Guide

Gas Burner Approximate BTU/HR Heating Guide

Gallons	BTU/HR
1-3	5,000
3-4	7,000
3-5	8,000
5-8	12,000
8-16	20,000
8-40	30,000

Watt

A measurement of electrical power. Rate at which one volt can push one ampere through an electrical circuit

One watt =.0569 BTU per minute

Approximate Percent Rated Watts When Reduced Voltage Is Applied:

• 120 Volt Heater On 115 Volt = 92%
• 120 Volt Heater On 110 Volt = 84%
• 120 Volt Heater On 105 Volt = 77%
• 240 Volt Heater On 220 Volt = 84%
• 240 Volt Heater On 208 Volt = 75%
• 240 Volt Heater On 120 Volt = 25%
• 480 Volt Heater On 440 Volt = 84%

OHM'S LAW

WATTS = AMPERAGE x OHMS

WATTS = VOLTS x AMPERAGE

W.C.

Water Column