This OK?

Not much gap between the furnace flue & liner. Technically, is this ok for zero clearance from the liner to other materials? Liner is hot to the touch.

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B vent is designed for venting approved gas appliances certified with draft hoods or diverters
producing nominal flue gas temperatures of 135°C and not exceeding 245°C (470°F).

Minimum clearance between the vent and combustible materials is 1".


Metal-Fab L-Vent systems are listed for gas and oil furnaces that do not exceed 570°F at the outlet temperature, and for 1700°F for a 10-minute “safety over-fire” situation. Metal-Fab L-Vent is only allowed for use with appliances requiring a negative or neutral pressure venting system.

Maintain a 3” minimum clearance to combustibles when passing through a combustible wall, ceiling or roof. **Always **use a Firestop when penetrating a floor or ceiling.

Type L-Vent is not listed for use with wood or coal fired appliances.

Thanks Marcel. I’m aware of the clearance requirements, my concern is the sufficiency of the liner/sleeve.

What kind of pipe was it Al.?:slight_smile:

Oops. Type B.

needs 1" clearance :smiley:

That elbow and that lower piece in the second pic don’t look like type “B” to me. It looks like single wall pipe. Single wall pipe has 6 inch clearance requirement and should not be used in concealed space. The “B” vent has 1 inch clearance requirement to combustibles.

The single wall in the pictures is fine as long as it is not in an unconditioned area.