All pellet heaters require 3" or 4" Type L (a double wall pipe with a stainless steel liner) pellet venting. Three-inch pipe is recommended for vertical runs under 10' or albtudes up to 3000 feet. Pipe runs over 10' or altitudes above 3000 feet. require four inch pellet pipe. Horizontal runs must be limited to 2 feet. A wall band is required for every 4 feet minimum on a vertical run up an exterior wall.
When exiting through the wall with Type "L" pellet vent pipe, you may go straight out through a wall thimble.
You must connect a pellet vent tee at this point and extend the vent pipe at least S feet vertically outside to provide good draft and allow the gases to exit. The tee must have a clean out cap for inspection and regular cleaning.
45 or 90-degree elbows add 20 to 30 per cent to the length of the run. For example a 7' vertical run with two 45-degree elbows will total 10 feet. so 4" pipe would be required.
Thelin Co. requires a minimum 5' vertical run on any installation. Direct vent (straight out the wall) and stop is not permitted.
All pellet vent pipe connections including exit at the rear of the heater should be sealed with high temperature silicone (450 degrees) or metallic duct tape. This prevents smoke and soot leakage into the living area. If this is not done, there is a possibility that the room fan will pick up any leakage and blow it into the room.