Aprilaire 4231 Replacement Yellow Orifice for Aprilaire Humidifiers

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Aprilaire 4231 yellow orifices are the tiny nylon components which accurately meter the flow of water into your humidifier. This allows for homeowners or technicians to quickly adjust the rate of water flow to the humidifier. Make sure the correct orifice replacement part is unique to your model of Aprilaire humidifier. Used in the following Aprilaire Humidifiers: Model 400 Model 400A Model 400M Model 500 Model 500A Model 500M Model 550 Model 550A Model 558 Model 560 Model 560A Model 568 Model 600 Model 600A Model 600M