SEE "DIGITAL-TO-ANALOG CONVERTER"

THE DECREASE IN AMPLITUDE OF AN OSCILLATION WHICH IS DUE TO THE DISSIPATION OF ENERGY

STANDS FOR DECIBELS

A MICROPROCESSOR-BASED COMPUTER CONTROL SYSTEM THAT PROVIDES DIRECT CONTROL OF THE MANY INDIVIDUAL COMPONENTS OF AN HVAC SYSTEM, WITHOUT THE USE OF CONVENTIONAL DEVICES SUCH AS THERMOSTATS.

THE TWO PREDOMINANT DDC SYSTEMS IN THE HVAC INDUSTRY TODAY ARE: JOHNSON CONTROLS' "METASYS" SYSTEM, AND HONEYWELL'S "DELTA" & "EXCEL" SYSTEMS.

THE INTERVAL OF TIME BETWEEN THE INITIATION OF AN INPUT CHANGE OR STIMULUS AND THE START OF THE RESULTING OBSERVABLE RESPONSE

THIS IS AN AREA THAT REPRESENTS "NO CHANGE"; IN OTHER WORDS, A POINT'S VALUE MUST EITHER GO ABOVE OR BELOW THE DEADBAND IN ORDER TO TRIGGER CONTROL ACTION OR AN ALARM.

SEE "DB"

PARAMETERS AND/OR SELECTIONS THAT HAVE BEEN MADE AT THE FACTORY

INCREMENTAL VALUES ON A TEMPERATURE SCALE. EXAMPLE: 0 TO 240 DEGREES F OR C.

A UNIT BASED ON TEMP. & TIME WHICH IS USED IN THE ESTIMATING OF FUEL CONSUMPTION AS WELL AS FOR SPECIFYING THE NOMINAL HEATING LOAD OF BUILDINGS IN THE WINTER TIME.

FOR ANY ONE DAY, WHEN THE MEAN TEMP. IS LESS THAN 65 DEG. (F) (18 DEG. C), THERE EXIST AS MANY DEGREE DAYS AS THERE ARE FAHRENHEIT OR CELSIUS DEGREES DIFFERENCE IN TEMP. BETWEEN THE MEAN TEMP. FOR THE DAY AND 65 DEG. (F).

A DIRECT DIGITAL CONTROL (DDC) SYSTEM DEVELOPED BY HONEYWELL THAT PROVIDES COMPLETE HVAC-BUILDING AUTOMATION

MASS PER UNIT OF VOLUME, SUCH AS POUNDS/CUBIC FEET

ACTION THAT SENSES THE RATE OF CHANGE OF TEMPERATURE, AND ALSO COMPENSATES TO MINIMIZE OVERSHOOT & UNDERSHOOT

SEE "CONTROL ACTION, DERIVATIVE"

SEE "SETPOINT, DEVIATION FROM"

THE SATURATION POINT OF A MIXTURE OF  AIR AND WATER VAPOR

SAME AS THE DIALATROL, BUT IS A SMALLER, MORE COMPACT VERSION

A TEMPERATURE CONTROL MANUFACTURED BY HONEYWELL THAT EITHER INDICATES AND/OR CONTROLS A PROCESS/LOOP, AND ALSO ACCEPTS A THERMOCOUPLE INPUT(S)

WHEN TWO PRESSURE SENSORS TRANSMIT THEIR SIGNALS TO A CONTROLLER, AND THE CONTROLLER THEN PRODUCES AN OUTPUT TO THE CONTROLLED DEVICE THAT VARIES IN ACCORDANCE WITH THE DIFFERENCE OF THE TWO SENSED PRESSURES

A SWITCH WHICH IS ACTIVATED BY AIR PRESSURE, AND IS OFTEN USED IN SUPPLY DUCTS TO DETECT FLOW OF PRESSURE DROPS ACROSS FILTERS

AN ON/OFF OR TWO POSITION SIGNAL USUALLY ASSOCIATED WITH A DIGITAL CONTROLLER

THE TERM USED TO DESCRIBE THE STAUS OF A DRY CONTACT, ALSO REFERRED TO AS A "GATE"

A CIRCUIT THAT ACCEPTS DIGITAL INPUT SIGNALS AND CONVERTS THEM TO ANALOG OUTPUT SIGNALS.

MAINLY ASSOCIATED WITH THE SIZE & PANEL CUT-OUT OF A PROCESS  TEMPERATURE CONTROLLER; DIN IS A GERMAN STANDARD AND STANDS FOR: "DEUTSCHE INDUSTRIAL NORM". MEASUREMENT EXAMPLES OF DIN ARE 1/8 & 1/4" DIN TO NAME A FEW

STANDS FOR "DUAL IN-LINE PACKAGE SWITCH".  MULTIPLE SWITCHES ON ONE CIRCUIT BOARD, EACH SWITCH HAVING THE CAPABILITY OF BEING SET TO EITHER ONE OF TWO POSITIONS.

AN INCREASE IN BRANCH LINE PRESSURE IN RESPONSE TO A RISE IN TEMPERATURE

SEE "DDC"

ON TYPICALLY TWO INPUT APPLICATIONS, WHEN A DECREASE AT THE SECOND OPEN-LOOP SENSOR CAUSES THE CONTROLLER SETPOINT TO DECREASE

A DAMPER OR DAMPERS WHICH ARE DIRECTLY LOCATED IN THE DISCHARGE OF EITHER A FAN OR A DUCT

ALSO REFERRED TO AS "DOS", CONTROLS THE TRANSFERRING OF INFORMATION TO AND FROM A DISK.

A THREE-WAY VALVE THAT DIRECTS FLOW TO EITHER OUTLET OR CAN PROPORTION THE FLOW BETWEEN THE TWO OUTLETS. MANT THREE-WAY/DIVERTING VALVES ARE USED FOR WATER-MIXING.

STANDS FOR DEPARTMENT OF DEFENSE

SEE "DISK OPERATING SYSTEM"

SEE "THERMOCOUPLE DOWNSCALE BURNOUT"

STANDS FOR DRIP-PROOF

STANDS FOR DOUBLE-POLE/DOUBLE-THROW

NORMALLY OCCURS IN TIME-PROPORTIONAL TEMPERATURE CONTROLLERS. IT IS THE DIFFERENCE IN TEMPERATURE BETWEEN SETPOINT AND WHERE THE TEMPERATURE OF THE SYSTEM STABILIZES.

THE AIR TEMPERATURE MEASURED BY A THERMOMETER

A CONTACT THAT DOES NOT IMPOSE AN ELECTRONIC SIGNAL FROM AN OUTSIDE SOURCE. A DIRECT SHORT OF NORMALLY-OPEN CONTACTS.

SEE "DIP SWITCH"

TWO-WAY DATA COMMUNICATION IN BOTH DIRECTIONS; PERTAINING TO DUPLEX THERMOCOUPLES HAVING TWO ELEMENTS

USUALLY ASSOCIATED WITH THERMOCOUPLES, MEANS THAT THERE ARE TWO (2) (DUAL) ELEMENTS INSTEAD OF ONE (1).

REDUCES ELECTRICAL CONSUMPTION BY PERIODICALLY TURNING-OFF EQUIPMENT FOR SHORT PERIODS OF TIME DURING NORMAL OPERATING HOURS. DUTY CYCLING IS NORMALLY A FUNCTION OF AN ENERGY MANAGEMENT SYSTEM.