Product review (5 stars): Booklet that came with it did NOT list the Aprilaire 550 (as in the listing). But everything was the same and fit just fine!
Easy to follow instructions. A bit stressed when the booklet that came with it did NOT list the Aprilaire 550. But after looking closely at everything it was the same and fit just fine! Although, I was not able to use the water filter part for the feed from the solenoid, but there wasn't one to be taken out, so I hope that's ok! Has been working well!