The Rinnai FOT-154 is a genuine Long Flue (D), 21-5/8 to 31-1/2 inch for All Rinnai direct vent wall furnaces. Long flue assembly for walls 21-5/8 to 31-1/2 inches thick.
This is an OEM Rinnai part, so it fits and performs the way the original did. Confirm your model before ordering; the model is on the rating label on the unit. If you are not sure which part you need, Rural Energy support can check it against your model and serial number.
Rural Energy is a Rinnai distributor and keeps Rinnai direct vent wall furnace parts in stock for fast shipping to dealers, contractors, and homeowners.