Generator Exhaust Stack

[Slow Rider]

I got to spend a little time in Phoenix.  Whenever I had the opportunity I went out to the Salt River for a little tubing.  Take LOTS of sunscreen.  If not you can do the same lobster man imitation I did.  If you spend a lot of time there, invest in a round cooler and rent the extra tube for it, sure it nice to have a cold beverage whilst enjoying the view.

Frank

http://www.saltrivertubing.com/

[Dreamscape]

SR, Thanks but No Thanks on the Salt River. I plan on staying white.

The Wall, OK now I understand. I bet I have some buddies from my stint in the Army on there.

Thanks Guys for some ideas. I lived here about 16 years ago and frankly just didn't like it here. The place sure has changed.

Now how about those generator stack ideas?

Paul

[belfert]

I thought a big reason to use the larger pipe with the air hole is to prevent excessive backpressure on the generator?

I like the idea of a long muffler pipe as it would be easier to make and attach.  My main concern would be folks burning themselves on it.

I really need something as I don't want to kill someone when boondocking at rocket launches with large groups of RVs and tents.  My travel trailer had a gas generator built in and a tenter set up next to me on the gnerator side.  I warned them about the generator mainly because of the noise, but they set up anyhow.  I never thought about the CO back then.

[JackConrad]

   My generator exhaust terminates just in front of the drive axle on the driver's side (under the back of the rear baggage compartment). I made my vertical stack by adding a 2' length of exhaust tubing to a 90 degree exhaust sweep. The sweep fits over the generator exhaust on the bus. I took a length of 3" PVC pipe and centered the 2' section of exhaust tubing inside one end of the PVC using screws through the PVC (2 sets of 3 screws spaced 120 degrees apart, one near bottom of the PVC pipe and one set near the top of the section of exhaust tubing). The PVC pipe is long enough to extend above the top of the bus several inches. I added a bracket near the top of the PVC pipe to hook on the drip rail. To make it easier to store, I cut the PVC Pipe in half and added a standard PVC connector.
   With the larger diameter of the PVC, the hot exhaust gases going up the pipe (heated gas rises) tends to pull cooler air in at the bottom. This cooler air does 2 things, it helps dilute the concentration of the exhaust gases and keeps the PVC pipe cool. The hottest spot on the PVC pipe is where the 2' section terminates. I have never seen this spot hotter than 104 degrees (checked with a laser temp gun)  Walking by, I usually grab the pipe at this hottest spot to check temps. It has never been hot enough that I could not keep my hand on it.  Jack

[Dreamscape]

Jack,

I like your idea a lot. Sounds simple but effective, and sure beats the higher retail price for what accomplishes the same thing.

Can you do me a favor and post a pic showing the exhaust sweep with the PVC connection and also maybe a pic of the upper hook on the drip rail?

Thanks,

Paul

[JimC]

I have been using two sections of aluminum gutter with an elbow on one end. The advantage is that there is virtually no weight to it, and it comes apart easily for storage, and when together it is over the roof line.

I anchor it to the bus with one small piece of angle attached to the gutter and one hole drilled into the body of the bus at the belt line that I tapped for a 1/4 X 20 bolt. Right now, the lower end just sits over the exhaust from the generator, but I will be adding another bracket lower on the gutter to keep it suspended so it does not touch the generator exhaust, that way it will not resonate as much noise through the gutter. But even now with the gutter sitting directly on the exhaust pipe the noise is not very loud.

Like jack said, it stays cool because it is over sized compared to the generator exhaust it helps to keep it cool because while while the exhaust is heading up the pipe it is drawing cool air in at the bottom along with it keeping the temp. down.

Jim

[JackConrad]

Paul,
   Here is the sweep in the bottom of the PVC pipe and the upper bracket that attaches to the drip rail. I made the bracket from a couple small scraps of aluminum angle and a couple buck rivets. It is attached to the PVC pipe wth a hose clamp. This allows use to adjust the bracket to allow use on someone else's bus which has been done a time or two.  Jack

[JackConrad]

Paul,
    Here are a couple more photos of the stack. One shows the stack in the storage rack in the center baggage compartment and the other shows in in place on the generator exhaust.  Jack

[belfert]

Jack, what did you use to center the exhaust pipe inside the PVC pipe?

[JackConrad]

I used 6  #14 SS Sheet metal screws through the PVC pipe with the tips of the screws against the short piece of exhaust tubing. 2 sets of 3 screws, one near the bottom of the PVC pipe and one near the top of the piece of exhaust tubing. Each set of 3 screws are space 120 degrees apart.  Jack

[Dreamscape]

Jack,

Thank You so much for providing the pics. That is a big help.

Good job and very simple.

Now I have a much better idea to fabricate my own.

Paul

[Bob Gil]

I just got my camera out and took these pistures of the way some one did mine.  Any you can see the tail lights I have just got installed for a test fit and to get an inspection so I can move it around some.

If you look you will see how they made it in 3 pieces and they fit in the bottom of the bus very well they even have thier own case to travel in.

Sorry I lost my power when I started posting this post

[H3Jim]

Jack,

Just to confirm, the 2" pipe only extends a short ways into the PVC pipe, the rest of the distance is just plain PVC.  What size is your genereator?  Mine is a 13k.  I'm trying to assess how much heat I'm dealing with.  Sometime ago I talked with Dick Wright about this and he was very concerned about the heat issue, stating that the exhuast gas temp would be close to 400 as it leaves the generator.  I do have a muffler, and about 5 feet of 2' pipe before it would go into the vertical stack, so it could get some cooling before going up.

I am wanting to install a permanent stack inside the bus.  Using something much like yours, but one that is permanently installed  and using just 3" PVC would make that process a lot easier for me.

I suppose that doing this I am concerned about leaks, and the possibiility of getting carbon monoxide inside the coach, but thats what being careful as well as using a detector is for.

[JackConrad]

Jim,
    The section of exhaust tubing that attaches to the sweep on the vertical stack is about 24" long. The rest of the PVC pipe is open.  Our 10 KW/ 3 cylinder Kubota powered generator is located in the OEM AC condensor compartment behind the front wheel on the drivers side. The 2" exhaust pipe runs under the bus to the rear of the rear baggage compartment where a 90 degree sweep attaches to a small automotive muffler. The chrome exhaust tip that sitcks out from under the bus is attached to the outlet of the muffler.   Jack

[D+C4106]

Paul,  For what it is worth here is my story!   I built a system very similar to Jacks after asking for this same information a few years ago.  We have an Onan 10 KW,  the exhaust is about 1 1/2" diameter and the PVC pipe used is  3" schedule 40.  The first time we used it was in Albuquerque (alt. 5000" +),  very warm day and probably had the water heater and two air conditioners running simultaniously.  The PVC became soft and did bend some after running for a while.  I have tried it after that with only 1 air conditioner and not much else running, it did not get soft at that time. We have not had the need  to use it often so the results are limited to these few times.  Hope this helps,   Denis