Category: Instruments & Devices

Flame Rectification Sensor

The flame rectification sensor is commonly used in high efficiency furnaces that use direct burner ignition. Direct Burner Ignition System Flame Rectification Circuit — Direct burner ignition systems light the burners using a hot surface ignition (HSI) or direct spark ignition method. In direct burner ignition systems, the flame sensing electrode (FSE), also called a […]

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Thermocouple

Thermocouples are used on residential gas furnaces equipped with standing pilots. A standing pilot is one which burns continuously, whether the main burner is on or off. A thermocouple standing pilot is only used with a 100% shutoff main gas valve. This type of gas valve shuts off gas to the pilot and will not […]

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Magnehelic® (Differential Pressure) Gauge

Magnehelic® differential pressure gauges provide a direct reading of pressure and/or air velocity. These gauges are used to measure filter resistance, air velocity, and furnace draft. Magnehelic® gauges capable of measuring just pressure or both pressure and air velocity are available. Single-scale pressure models, calibrated either in inches water column (in. w.c.) or psi, are […]

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Hygrometer

Hygrometers (Figure 1-36) are used to measure the relative humidity in a controlled space. Hygrometers are also commonly called relative humidity meters. See Item 16 for a description of relative humidity. Many types of hygrometers are available. The dial-type hygrometer uses a synthetic hair that expands and contracts as the humidity changes. Many humidifiers also […]

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Psychrometric Chart

Psychrometrics is the study of air and its properties, including temperature, pressure, moisture, and other characteristics. Control o f these properties is essential for human comfort, optimum equipment operation, and to prevent damage to home furnishings. Psychrometric charts show the relationships o f these air properties graphically. A brief description o f the psychrometric chart […]

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Velometer

Velometers (Figure 1-32) are used to measure the velocity of airflow. Like the anemometers described previously, velometers are used when evaluating the operation and/or balancing the airflow in air distribution systems. Velometers provide instantaneous, direct readings o f air velocity in FPM without the need for timing or calculations. Some can also provide direct readings […]

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Anemometer

Anemometers are used to measure the velocity of airflow. Measurement of air velocity must be performed when evaluating the total operation of an air distribution system. It must also be done when adjusting an air distribution system to balance the volume of air in cubic feet per minute (CFM). When evaluating and/or balancing an air […]

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Hermetic Compressor Analyzer

The hermetic compressor analyzer (Figure 1-28) is a single test instrument used to make multiple tests on hermetic compressors. This device eliminates the need for using a combination o f other test instruments such as the capacitor tester and volt-ohm-milliammeter. Similar to a clamp-on ammeter, the hermetic compressor analyzer uses clamp-on sensors that allow testing […]

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Capacitor Tester

The capacitor tester (Figure 1-27) is used to test capacitors to determine their specific capacitance value and to find out if they are good, open, or shorted. For field service work,, most technicians usually test capacitors using the resistance (ohmmeter) function o f the VOM. There are times, however, when it is necessary to determine […]

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