When using any PTFE heatbreak the PTFE tube itself is responsible for creating the seal between the tubing and the nozzle.

Assembling a hotend with a PTFE heatbreak is like an all metal one except you will need to make sure the PTFE tube has pressure on the back of the nozzle to seal correctly.

1. Install the nozzle all the way into the heaterblock
2. Back the nozzle out 1/4 turn from the heaterblock
3. Install the heatbreak into the heaterblock until it hits the back of the nozzle
4. Install the assembled heatbreak+heaterblock+nozzle into your hotend heatsink
5. Unscrew the PTFE fitting from your hotend 1/2 a turn*
6. Make sure your PTFE tube is cut squarely and flat
7. Insert the PTFE tube all the way into the hotend until it stops
8. Tighten the PTFE fitting down all the way*
9. Heat the hotend to 240C
10. Tighten the nozzle down with a wrench with the force of 1 finger (do not over tighten)

* If you have an E3D Hotend or one that does not have a screw in type PTFE fitting unscrew the nozzle 1/2 a turn instead of the fitting. The nozzle will need to be tightened back when the nozzle is at 240C.