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The Aprilaire 4004 In-Line Strainer is a tiny strainer that fits in the inlet fitting of the water solenoid valve which allows water to enter your humidifier. It is designed to keep debris from entering the solenoid valve and should be checked periodically. See the owner's manual section labeled "Periodic Preventative Maintenance" for more information.

Used in all models except for Commercial units and residential models 110, 112, 445, 445A, 448, and 330.
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This item is compatible with the following Aprilaire, Broan model numbers.

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Please note: Many replacement parts have subtle differences between them and can be easily confused. Attempting to install the incorrect part voids the return coverage. If you are not completely sure your order is correct please give us a call at 1-888-757-4774.

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