Cutting concentric venting for a Tankless heater

There is a special way to cut concentric venting for a Navien tankless heater.
It might seem intimidating, but it becomes much easier after a few times.
Here is a list of tools you will need to cut the venting,

Paper, Card stock to make the ring cut line.
marker
saw
Dremel tool and bits
reamer, knife
rags
tape measure
tape
It is very important to cut the venting exactly as I show it in this video, if not you will be drawing in the CO back into the combustion chamber and that will be used to make combustion causing the burner to vibrate.
If you are interested in my training or would like to ask a question, please e mail me at economyplmbg@aol.com
I hope you enjoy this video,
Mike
ONLY A LICENSED PLUMBER CAN BUY OR INSTALL A NAVIEN TANKLESS HEATER. PLEASE FOLLOW ALL LOCAL AND NATIONAL PLUMBING AND GAS CODES AND TO FILE A PERMIT AND OBTAIN AN ENSPECTION FROM YOU LOCAL BUILDING DEPARTMENT.

Видео Cutting concentric venting for a Tankless heater канала That Tankless Guy