What material for generator stack?

[belfert]

I need to build a generator stack.  What would be the best material to use if starting from scratch?

FRP/fiberglass pipe is probably best, but also spendy.

[Blacksheep]

What I did was go to Radio Shack and purchased a steel mast. It's 3 pieces but I only use 2. It's telescoping as it fits inside each other. By this feature it can be taken apart and stored very easy! Only thing I had to make was an elbow from the gen exhaust! I also made a tripod that fits to the elbow that holds the pipe upward away from the coach! When the tripod is attached, and the bus airs itself down, the tripod is set. I don't use any hooks, wires, straps, bolts of any kind to attach it (the pipe) to the coach!
Next thing I will do is make me an outer cover to insulate the pipe. It DOES get a little warm to the touch (IF you touch it)! Don't ask me how I know!

Ace

[H3Jim]

Ace,
have any pics?  LIke to see waht you did.  I'm still venting under the bus - not good.

[Lin]

Am I to take it that you did not like my exhaust hose method?

[makemineatwostroke]

Check the FMCA archives there are articles on how to build stacks for generators some plain and some advanced or buy one from a rv supply camping world has the system

[JackConrad]

   We made our stack using an exhaust 90 degree sweep and a short length of exhaust pipe. We slipped this inside a length of 3" PVC Pipe. The exhaust pipe is kept centered by 2 sets of 3 screws.  The exhaust pipe only extends about 2' into the PVC pipe.
    When in use, the hot exhaust gas rising in the pipe pulls ambient air in at the bottom. This serves 2 purposes, it cools the exhaust gaes & pipe as well as diluting the exhaust gases.
   The 3" PVC has a coupling in the middle for easier storage and a clip near the top to hook on our drip rail.  I had most of the neccessary parts laying around in my shop, but it probably would not cost more than $10-15 to make one.  Jack

[JackConrad]

Here is a photo of completed pipe in use.  Jack

[Len Silva]

Jack,

You need to paint some red stripes on your pipe!

[JohnEd]

Jack,

That is a Winner.  Thank you,

John

[Hartley]

Oh and Don't forget to "TUNE" the pipe to kill off the resonance of the exhaust pulses. Or your next door neighbor will be complaining.

There have been some nice looking stacks at the rallys however some have a droning  low frequency hum that tends to fratter nerves 50 feet away although sound very quiet close up. ( Pipe organ style. )

The other thing to keep in mind is that PVC pipe droops and or melts when exposed to 300+ degree heat. You must have the pipe centered perfectly every time.

I used Steel (EMT) conduit for mine with stock elbows and couplers.
It's HOT but quiet. Never did get around to figuring out what to do with 10 feet
of EMT for transport. Usually stuck it inside along the wall or in the trailer.

So I am wierd and CHEAP...Oh wait I am too poor to be cheap!...

Dave....

[JimC]

I used two sections of aluminum gutter downspout cut to just over the roof line with an elbow on the bottom, the elbow sits over the generator exhaust. Taken apart they store nicely for transport. Because there is so much room inside the gutter, it stays pretty cool to the touch, much like Jacks, it draws cool air into it from the bottom and it goes up with the exhaust.
Jim

[H3Jim]

how hot does it get.  I am thinking if the pipe was connected directly, and run for hours, that it might get up to300 or 400 degree.  The way Jack has his, it gets that cooling ambient air.  But max temp is pretty important to consider..

[JackConrad]

how hot does it get.  I am thinking if the pipe was connected directly, and run for hours, that it might get up to300 or 400 degree.  The way Jack has his, it gets that cooling ambient air.  But max temp is pretty important to consider..

First, our exhaust pipe from the generator runs about 15' under the bus, makes a 90 degree sweep and attaches to the muffler which is located just in front of the drive axle on the driver's side of the bus. the output end of the muffler is where we attach the vertical stack. The hottest temperature I have recorded on the metal sweep of the vertical stack is about 140 degrees. The hottest spot on the PVC part of the stack is at the point where the inside length of metal exhaust pipe ends. The outside of the PVC pipe at this point is usually around 100 degrees. I have never seen it hot enough that I could not keep my hand on it.
   I do not know how much hotter it would be if I did not have the 15' run of exhaust before the muffler. I was told that this 15' run of 2" exhaust pipe would help absorb/stop the exhaust pulsations.  The other reason we had for the long run was to try to separate the sources of noise from the generator. With exhaust back by the drive axle, the generator in the OEM condenser compartment, and the radiator/fan in the OEM spare tire compartment, no matter where you stand, you only hear part of the noise from the generator.  Jack

[belfert]

How would schedule 40 or 80 PVC electrical conduit handle the heat?  I am thinking the bell end would be good to couple the two pieces.

I only have about 4 to 6 feet of exhaust pipe including the muffler.

[Ednj]

You need the fresh air space, you know like a double wall stove pipe.
The way Jack has his are just like the ones they sell at rv places.