Now i do have experience with technology change versus construction framing.
Clear attic furnace flue.
Because the pipe gets hot building codes usually require 1 inch of clearance from metal flues 2 inches from masonry chimneys to any combustible material including insulation.
This will stop the air from getting a free ride along the chase and heating your attic.
Municipalities may require a minimum of 30 clear inches in front of the furnace which can be accomplished in a small room if the door to the room opens in front of the furnace.
How to check for creosote.
Nail them both on the attic floor so they butt up against the flue.
The vent should always be clear.
While you are at it look around for all other duct chases in your attic.
2015 irc m1305 recommends that the furnace have a level working space of at least 30 inches by 30 inches in the front of the appliance.
You can reduce creosote buildup in your fireplace flue by providing adequate combustion air which will encourage a hot clean burning fire.
Of clearance from class b flues 2 in.
From masonry chimneys to any combustible material including insulation.
American gas association has certified the design of condensing furnaces for a minimum of 0 clearance from combustible materials with a single wall plastic vent pipe.
Cut away any branches or remove any object that might be obstructing the pipe and creating debris.
Then use fire rated caulk to seal the gap btw the sheet metal and flue and then the sheet metal to the attic floor.
Not much furnace experience around here that s just a heating coil on the end of the a c blower used for 7 8 weeks a year g.
Apply a thick bead of high temperature caulk the flue on one.
Remove the insulation between the joists where the flue is located to clear an area about 18 inches away from the flue on each side.
The vertical flue at the ceiling level is surrounded by and attached to a horizontal piece of open 1 2 x 1 2 metal mesh screen about 10 square.
The metal furnace flue extends vertically through the closet ceiling through the attic and roof.
See direct vents side wall vents for a complete table of recommended clearance distances from a direct vent gas appliance terminal to other building components or features.
Because the pipe gets hot building codes require 1 in.
Wipe it clear with a rag or soft cloth and then replace the cap.
Furnace flues require special sealing techniques the opening around a furnace or water heater flue or chimney can be a major source of warm air moving in the attic.