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Statement Regarding Exhaust Extensions
Cummins Power Generation, manufacturer of Cummins Onan generator products, does not endorse the use of RV generator exhaust pipe extensions. Like all fuel burning devices, engine-driven generators emit carbon monoxide (CO) which, if not safely handled, can produce serious injury or death.
Cummins Onan generators, in conjunction with RV OEM installed tailpipes, are designed to meet RVIA standards for safely handling exhaust gasses while minimizing noise and maximizing generator performance. Improper modifications to the exhaust components can result in unreasonable hazards to the vehicle occupants.
Cummins Power Generation has been unable to this date to identify any commercially available exhaust extension kit which meets reasonable standards for safely handling exhaust gases.

Cummins Power Generation’s concerns revolve around 6 areas:
1. Weight: Unless entirely self supporting, extensions add weight to the end of the generator tail pipe which can stress and crack or break the exhaust system parts that are not designed to carry the additional weight. This could result in exhaust gases escaping directly under the coach, and therefore could be extremely dangerous to vehicle occupants.
2. Fit: To be effective conveyors of exhaust, connections & joints must be gastight. Such connections are not guaranteed unless the exhaust extension kit is properly assembled each time it is used.
3. Exhaust Direction: Because exhaust extensions vent at the roof line, there is a major concern that exhaust will be sucked in by rooftop air conditioners, vents and windows.
4. Heat: Many extension designs involve exposed metal that can be a burn hazard to anyone passing by who might contact the exposed extension pipe.
5. Backpressure: Adding an extension may increase backpressure on the engine, and thereby reduce engine performance or cause the engine to fail meeting government-regulated exhaust standards.
6. Warranty: The use of an exhaust extension kit may void the Cummins Onan warranty.
Larry Shaw