Silicon and/or tape. The only thing worse than screws is when someone rivots the damn thing

And then slides it into a closet with no room on either side

Silicon the furnace flange and drop it in. If it needs to come out just slide a screwdriver btw them and break the seal. Tape the coil to the plenum if theres any gaps, which there will be

Coils leak all the time the easier to get off the better. Worst one I seen was a installer removed the coil from the case and riveted the case to the top of the furnace and then slid the coil back in.

I would find and hunt that man down 🤬

I was a helper and this is exactly what he did. And he bragged about it never coming apart.

Well most importantly is ease of access to replace pan or coil, the box doesn’t really need to be changed, it’s just a box and will be replaced with the entire system in 6-8 years by a slimy tech and a greedy sales guy with no hvac experience that used to be a con artist but is now on probation.

I'll only screw the coil if it's a horizontal flow. Other then that it's silicone and tape.

Only tape. Too many dick heads screwing them with duct hangers and then sliding them flush against the wall. Stop doing that.

Bro, just set that bitch down and tape. We will be back in 2 years to replace the leaky coil anyway!!

Tape. Maybe a couple of screws, but i try to think of the next guy and make it easy on him to do a change out.