HVAC experts, I need your help, relatively fast

In basement of the 90-year-old house that we are about to sell, there was some asbestos ceiling tile above the furnace in the basement. We hadn’t known about it until our home inspector pointed it out, so we had it professionally removed.

My question is, do we need to replace it with a new heat shield of some kind?

The basement is unfinished, with wooden joists about six feet above the furnace. There is no insulation between the joists, just the original wooden floorboards of the room above.

The pictures hereshow the old asbestos tile (now removed) and the current furnace.

My thinking is that the asbestos was probably installed long before the current furnace, to protect against the heat generated by an older, larger, and less efficient unit. I don’t get the sense that this furnace could possibly give off enough heat to damage the wood above it, so I’m wondering if installing new heat shielding is necessary. But I’m no professional, and I don’t know building codes or standard practices in this area.

To be clear, I’m not trying to cut corners or do anything unsafe. I want to make sure there’s no fire or other safety risk. But if there’s no need for a new heat shield, I’ll be happy to save that expense.

Unfortunately I don’t know the exact age of the current furnace. I hope to get that info and post it here in the next day or two.

Related questions: When was asbestos tile like this common, and when was it banned from this kind of application? IOW, how old was that stuff?

(I know that Dopers have opinions about everything, but I’d much prefer informed opinions from people with professional experience in the field over WAGs. I’m plenty good at WAGing!)

Thanks.

Updates: I’ve found out that asbestos-containing millboard of the type that was on the ceiling was never banned by the US EPA, but most manufacturers stopped making it around 1976.

And I’ve learned that the current furnace (more properly called a boiler) was manufactured in 1992. (I don’t know when it was installed. My wife bought the house in 1996.)

So presumably the ceiling tile was installed at least 16 years before this boiler, probably more. This confirms my suspicion that it may have been needed for an earlier boiler, but almost certainly wasn’t installed for this particular unit.

Also, according to the manual for this boiler (PDF!), the top clearance to combustible materials is 18 inches, far less than the distance to the joists (at least 3 feet).

So I’m becoming more confident that reinstalling some form of heat shield isn’t really necessary. But if anyone here knows, or has reason to believe, differently, please let me know.

at 90 years old the original was likely a monster coal unit that might have been huge and close to the ceiling.

you have more than the required clearance so nothing is needed. having open is better.