Carrier APU - Replacement Muffler

In another thread the noise of the Carrier APU has been brought up, and I thought it would be worthwhile to start a separate thread, since there are many on here who run Carrier/Pro-Heat APU's..

Has anyone replaced the Carrier muffler with one that dramatically cuts down on the noise??

Would the Tri-Pac muffler (they run very quiet) be suitable?? I've had a mechanic say that a golf-cart muffler might work.

I've read on here that routing the exhaust through the engine muffler presents problems, so am assuming that that proposed solution is a no-go.

 

Tom,

It's possible you might find the right golf cart muffler to do the job. There seem to be many different configurations available, so a multi-line dealer would be the best place to look for the closest fit. Should you find a muffler that works to quiet the APU while requiring few modifications to adapt for truck use, compose a flyer with the model number and installation instructions and then offer it for sale in download form for a small fee. Flatbedders will then distribute them throughout Truck Stops across America...

Have you tried looking to Carrier for a solution? When looking for quieter mufflers I just stumbled across the news about their CARB Compliant Clearsky DPF. That will retrofit to at least some of their earlier APU's in place of the existing muffler while eliminating some noise. I've yet to learn the price for one, but I also see that golf cart mufflers can be spendy too...

While you're on to them, ask about alternatives for air filter housings... These too can have quite an effect in quieting an engine.

Good hunting!

 

Just like a car you should be able to put any kind of muffler on you want, the bigger and more restrictive it is the quiteter it will be...



American Trucker

 

AFAIK the CARB compliant re-fit is around the $1200 mark, waaaaay too spendy, especially since I have vowed never to go to CA again. :biggrin_25520.gif:

Now that you mention it, I seem to remember something was written on another forum about the air intake being responsible for a fair bit of the noise.

Thanks

 

I' m in the process of installing a Onan 4000 KW RV generator. How is the exhaust pipe routed? Should the exhaust pipe be routed to the end of the frame. A little help please?

 

I thought I read that people were tapping the exhaust of their APU's into the exhaust before the DPF filter to make it CARB compliant.

 

It's always best if the exhaust is routed to the end of the frame, but if that's not possible, at bare minimum make sure it's 3' away from the sleeper (pointed backwards and down at a 45 degree angle is best) so that in windy conditions the fumes from the exhaust don't get trapped under the sleeper and seep in.

 

I saw a truck with a diesel fired heater mounted under the hood near the frame rails on a Freightliner Columbia. The exhaust exit under the hood. I don't know who put that on there, but I told them that would not fly with DOT. All exhaust must exit PAST the cab with the exception of stacks that go above the cab.

 

You can only legally do that if the engine and apu are made by the same company, so the only legal one was the Comfortguard by Cummins/Onan, which they discontinued.