I am in the process of replacing my RadonAway RP145 fan (15 years old).

What is this black box on top of the fan?

I cannot find any info about what it is used for and if that needs to be replaced too.

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1 Answer 1


Since you're replacing the fan anyway, remove the black box and check it out. It could be a check valve or a filter. It looks like it just unscrews and you could see what's inside. There might be some identifying markings on the back side.

  • 1
    Yes, it's probably a backflow prevention device.
    – isherwood
    Commented Jan 19 at 15:06

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