Boiler Room Ceilings: code?

vaporvac

Since the concrete ceiling above the old boiler was coming down, we went ahead and took down the rest. Is there anything that needs to replace it? I've put up 1/4" drywall just cause I had it. I'm most concerned around the vent. On top of the concrete was some sort of heavy insulating board covered by metal. I imagine the flue got hot. Is that necessary with these new boilers? I'm happy to put up concrete board on the whole thing or just in that area covered by metal sheathing if necessary. I did a search and couldn't find anything relating to this subject, nor do I remember reading anything it.

Jim_from_Worcester

Boiler Clearances

Should be specified in your equipment's manual, and the International Mechanical Code (IMC) defers to the manufacturer in that regard, unless unspecified or less restrictive than the IMC. In cases of clearance reductions you need to refer to the table in section 308 and extrapolate the clearance in a linear fashion from the manufacturer's clearances. The clearance reductions are usually accomplished with sheet metal, but inorganic sheet products such as sheetrock or cement board need to be a minimum of 1/2", and, if I recall correctly, they need to be set off from the combustible surface a minimum of 1" using non-combustible fasteners, spacers or blocks.



Also, check your state's amendments to the IMC,as they might be slightly different.

ChicagoCooperator

Check your local codes too.

Check your local building codes too, many municipalities have "quirks" regarding furnaces and boiler rooms. 

vaporvac

Just near the chimney...

Thanks. I'll have to get the specifics tomorrow, but I think I'm good with the clearances by a wide margin. the ceilings are 9ft. tall. It's mainly where the furnace enters the chimney. As you can see in the pic it is right below the ceiling. ( (You can just make out the screws in the ceiling's new drywall. Just so you know at what you're looking.) I suspect I'm looking at concrete board and putting back the metal.

Colleen

Jim_from_Worcester

Code and SF require

A vent clearance of 18" from combustibles. The SF manual mandates the Nat. Fire Protection Assn. (NFPA) standard 31. Check to see if the IMC is used in your area, though, because I think it is slightly more restrictive and would therefore trump NFPA 31. They will tell you essentially the same info, but NFPA 31 will allow a 50% clearance reduction using only 1/2" insulation board and an air space, whereas the IMC will not. They will both allow a 33% reduction when the board is paired with 1" fiberglass or rock wool directly against the framing.



Your best bet is to put up 24-gauge sheet metal open on three sides (run it tight against the chimney) spaced off the framing with 1" pieces of metal conduit or piping--you won't need much, typically.



Can you post a picture that shows where the boilers are going and the relative distances around the chimney? It is a bit difficult to gauge what is going on. Is the duct in the picture from the old boiler? If so--and you likely are aware of this--it is not adequate for the new boilers. I believe you will have to maintain the vent size and geometry on the boiler (9" pipe?) flush to the inside of the stack. Someone please correct me if I'm wrong on that.



Best of luck--it sounds like a fun project.