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.
http://www.ventingpipe.com/safety-vent-pipe-tips/c60:)
TYPE “B” GAS VENT
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".
TYPE “L” TEMPERATURE VENTING SYSTEMS
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.?
Oops. Type B.
needs 1" clearance 
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.