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  2. Central heating - Wikipedia

    en.wikipedia.org/wiki/Central_heating

    Overheating is prevented by a safety switch called a limit controller or limit switch. This limit controller may shut the furnace off if the blower fails or if something is blocking the air flow. The heated air is then sent back through the home through supply ducts. In larger commercial applications, central heating is provided through an air ...

  3. Piping and instrumentation diagram - Wikipedia

    en.wikipedia.org/wiki/Piping_and_instrumentation...

    Furnace: Cooling tower: Heat exchanger: Coil heat exchanger: Cooler: Plate & frame heat exchanger: Double pipe heat exchanger Fixed straight tubes heat exchanger: U-shaped tubes heat exchanger Spiral heat exchanger Covered gas vent Curved gas vent Air filter: Funnel or tundish: Steam trap: Viewing glass Pressure reducing valve: Valve: Gate ...

  4. Electronic symbol - Wikipedia

    en.wikipedia.org/wiki/Electronic_symbol

    Wire crossover symbols for circuit diagrams. The CAD symbol for insulated crossing wires is the same as the older, non-CAD symbol for non-insulated crossing wires. To avoid confusion, the wire "jump" (semi-circle) symbol for insulated wires in non-CAD schematics is recommended (as opposed to using the CAD-style symbol for no connection), so as to avoid confusion with the original, older style ...

  5. Furnace (central heating) - Wikipedia

    en.wikipedia.org/wiki/Furnace_(central_heating)

    The fourth category of furnace is the high-efficiency condensing gas furnace. High efficiency condensing gas furnaces typically achieve between 90% and 98% AFUE. [3] A condensing gas furnace includes a sealed combustion area, combustion draft inducer and a secondary heat exchanger. The primary gain in efficiency for a condensing gas furnace, as ...

  6. ANSI device numbers - Wikipedia

    en.wikipedia.org/wiki/ANSI_device_numbers

    71 - Liquid Switch, Level Switch; 72 - DC Circuit Breaker; 73 - Load-Resistor Contactor; 74 - Alarm Relay; 75 - Position Changing Mechanism; 76 - DC Overcurrent Relay; 77 - Telemetering Device, Speed Sensor; 78 - Phase Angle Measuring or Out-of-Step Protective Relay; 78V - Loss of Mains; 79 - AC Reclosing Relay / Auto Reclose; 80 - Liquid or ...

  7. Mercury switch - Wikipedia

    en.wikipedia.org/wiki/Mercury_switch

    A Single-Pole, Single-Throw (SPST) mercury switch on millimetre graph paper, device length approximately 1.5 cm Another mercury switch design. A mercury switch is an electrical switch that opens and closes a circuit when a small amount of the liquid metal mercury connects metal electrodes to close the circuit. There are several different basic ...

  8. List of gases - Wikipedia

    en.wikipedia.org/wiki/List_of_gases

    This list is sorted by boiling point of gases in ascending order, but can be sorted on different values. "sub" and "triple" refer to the sublimation point and the triple point, which are given in the case of a substance that sublimes at 1 atm; "dec" refers to decomposition. "~" means approximately. Blue type items have an article available by ...

  9. Control loop - Wikipedia

    en.wikipedia.org/wiki/Control_loop

    A control loop is the fundamental building block of control systems in general and industrial control systems in particular. It consists of the process sensor, the controller function, and the final control element (FCE) which controls the process necessary to automatically adjust the value of a measured process variable (PV) to equal the value of a desired set-point (SP).