Do I Need A 4-Bolt To 2-Bolt Adapter For A Dometic 411 Toilet?

Published 06/10/2026

Question:

Replacing seal and 511 out to domestic 411 do i need 4 to 2 Bolt pattern do i just need flange or do i need the full kit

asked by: Robert A

Expert Reply:

Hey Robert, thanks for reaching out. If you're going from a Dometic 511 to a Dometic 411, you'll need to check which floor flange is currently installed. The 411 uses a standard 2-bolt RV toilet flange, while some older 511 installations used a 4-bolt pattern.

If your coach has the older 4-bolt flange, you'll need a 4-bolt-to-2-bolt adapter kit like part # DOM73FR, not just a seal. The adapter gives the new toilet the correct mounting pattern and typically includes the necessary hardware. If your existing flange is already a standard 2-bolt style, then you can reuse it and just install the new floor seal that comes with the 411.

The easiest way to tell is to remove the old toilet and count the mounting bolts in the floor flange. If you see four mounting points, you'll want the full adapter kit. If you only see two, you're good to go with the standard 411 installation.

expert reply by: Jesse M