Rinnai direct vent wall furnaces must vent the flue gases to the outdoors. The flue manifold kit helps vent these gases through an exterior wall between 9-1/2 to 15-3/4 inches thick.
I got these on a whim, to try them out and very much enjoyed them. My supply is almost out and I will purchase them again. I am healthy and feel good, and it may or may not be because of these capsules.. Marcy S.. Tue Mar 30 2021