This weekend, I replaced a non-functioning ceiling fan in our home with a new one. The home is over 100 years old. When I replaced the fan, I found what is pictured in the attached image. It seems to be an old style pancake box with a center stud mounted to a ceiling joist. The mounting bracket and nut over the center stud used to hold the previous fan, which had been there for several years. (The old fan was there when I moved in.) I showed these pictures to the employee at a big box home improvement store, and he said "yeah, you can totally attach a new fan to that center stud and bracket! I live in an old house too and I've done that for lots of fans."
So I did, and I covered and sealed up the hole as well, because there's some old insulation in the attic I don't want leaking down into the room. Now I'm reading about fan-rated boxes, and I'm worried I did something bad. (Do your research first, kids!) I'm terrified this old box isn't strong enough and the fan is going to fall on someone. Here's what I'm trying to figure out:
1) Am I in danger? That old box and pipe seem pretty beefy, but I know fans are heavy and motion can wear things down over time. I also have no idea what I'm looking at. I should add this is over a bed, so someone will be under it for several hours at a stretch, and not alert.
2) Is there some way I can brace or reinforce this from above, up in the attic, so I don't have to open (unseal) everything up again?
3) If I don't want to mess with that old box and all the other electrical in there - because I have no idea what it is - would I be better off returning the fan and just installing a light, which wouldn't put stress on the box?
EDIT: I noticed the packaging says to use a box rated for a 35lb or less fan, so this is not a very heavy fan.
EDIT #2: I was able to get into the attic and look at the mounting from the top. The threaded pipe with the fan bracket seen in the "from below" appears to go all the way through the mount, loops over a crossbeam, under another joist, and runs all the way across the attic floor. (Not the conduit, the darker pipe next to the conduit) Due to the light oxidation, I think it is steel. It could be iron, but I didn't think iron pipes could have smooth bends like this one does? In any case, I know it isn't up to any modern code, but it seems very strong. The only risks I see now are 1) the fan bracket failing, which seems unlikely since it is designed to be a fan bracket, or 2) The threads in the nut or pipe somehow strip, which also seems unlikely given they are steel.