My new Goodman GMVC91155DX Furnace is about to be installed. I need to know what size filter to by. Spec sheet says it takes a 486.. I have never seen filter sized like this?

Can anyone help me covert the size to something I can buy?

Once the furnace is installed there is usually a filter grill installed on the return portion of ductwork near the furnace, so you will just need to measure this opening and go buy a filter that size. If you plan to use an internal filter(not recommended beause its just to easy to forget about it) the installer should be able to tell you what size filter you need and show you how to place it correctly. Hope this helps.

PS. I believe the 486 may be just a part number