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The magnehelic measures duct pressure inside of ductwork. It is important, for many reasons, to know the pressure inside of ductwork. This magnehelic measures the supply side pressure of the blower inside the air handler. Read more below.
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The magnehelic measures duct pressure inside of ductwork. It is important, for many reasons, to know the pressure inside of ductwork. This magnehelic measures the supply side pressure of the blower inside the air handler. The static pressure in this system is actually controlled by a static pressure transducer which is directly hooked up to a DDC controller that controls a variable frequency drive based on static pressure. The static pressure transducer is a solid state magnehelic and works in much the same way a magnehelic works except the transducer is digital and sends out a signal that registers the pressure it is reading. The magnehelic pictured is simply for visual display and reading the static
pressure inside the air handler. It does not send out any signals. A technician can walk up to the air handler in a quick glance tell if everything is okay with the blower and duct system based on pressure. Pressure sensors with switches in them are also used to determine a filter staus. A differential pressure switch can be installed in an air handler with pressure probes on either side of the filter. A differential pressure setpoint is adjusted into the switch so that when the filters load up the switch trips and sends a signal to the DDC controller. This alerts the operator of the system that the filters are loaded up and need to be changes. This differential pressure switch is usually calibrated and set using a magnehelic pressure sensor.
