Generator exhaust

[luvrbus]

H3Jim, email Hal St Clair his goes through the roof and has for years with no problem he can tell what he used

[H3Jim]

Lin,

I don't use the generator much, but its conceivable that I would run all three roof airs for hours on end, and the exhaust would get to the max temp.  If I was running it outside and many have done, I'd be less concerned, but inside through the coach carries the risk of CO2, not to mention water leaks if something deforms enough, etc

The location  of the muffler makes it more difficult to run the pipe to the side of the coach, as opposed to going up.  The only way In can get to the side, is by having it be the lowest point in the bus underside.  I'd hate to scrape it off going off road as I do sometimes.

[H3Jim]

Hal's is in the very back of the bus and does not really go through the interior

[luvrbus]

What do you guys do with the exhaust from the Pro-Heat ,Webasto and the Aqua Hot they smell and smoke as much as a generator and exhaust at 500 or 600 degrees and I don't recall ever seeing those with a stack

[JackConrad]

What do you guys do with the exhaust from the Pro-Heat ,Webasto and the Aqua Hot they smell and smoke as much as a generator and exhaust at 500 or 600 degrees and I don't recall ever seeing those with a stack

     We do not put a stack on our ProHeat, although I would like to. ProHeat's installation manual states no more than 5' of exhaust with minimal bends.  I was concerned that the stack might create to much backpressure resulting in carbon build-up in the burner.   Living and traveling in the SE, spending the winter in the southern half of Florida, our ProHeat rarely runs more than 20-30 minutes per hour when in use. We rarely need our ProHeat. 
    As fas the hot temperature, yes, you are absolutely correct.  I have thought about putting a warning label on the side of the coach right above the exhaust (but of course, many would just have to touch it to see if it really was hot LOL)Jack

[Lin]

To answer Jerry's question

with a 7.5 Kohler gas generator pushing one AC, after 45 minutes and an ambient temp of about 100, the temps are:
1. center of exhaust manifold- 650
2. pipe entering the muffler (about 14 inches away)- 550
3. end of exhaust pipe (about 3 feet from other end of muffler)- 160
4. exhaust hose at 6 foot from connection to exhaust pipe- 130 (and still touchable)

Since the exhaust exiting the top of the hose/stack seems to be close to 150, it is possible the hose will continue to heat up a bit, but it is well within the specs of the hose. 

[Sojourner]

Thank you Lin for your time and effort.

BTW...I corrected my confusing grammar of the previous IR post. Sorry.

About exhaust from Aqua and ProHeat would be added to this finding if any one is willing to.

Anyone else would like to share their finding of both Generator and heater exhaust temp?

Thanks

Sojourn for Christ, Jerry

[JackConrad]

I have shot the temp of our Proheat exhaust where it terminates about 2" beyond the side of the bus and only about 12-16" from the burner. Temp is 425-475 degrees.  When camping and we may need ProHeat, I always check under the ProHeat exhaust for any tall grass or other flammable material.  Jack

[Lin]

Jim,

I don't know your exact situation, so any suggestion may just be irrelevant, but I was wondering whether there might be a different option.  For example, if you could use high heat braided hose and find a way to snake it to the side.  Another thing I was thinking of would be to make the exhaust pipe wide and narrow to keep it high off the ground.  For example, wouldn't a 1/2" x 7" tube have the same capacity as a 2" pipe?  The surface area would actually be more, but maybe you have to allow for extra resistance.

[JackConrad]

The location  of the muffler makes it more difficult to run the pipe to the side of the coach, as opposed to going up.  The only way In can get to the side, is by having it be the lowest point in the bus underside.  I'd hate to scrape it off going off road as I do sometimes.

Jim,
  If you brought the pipe straight out to the side, would it be close to the front or rear axle? The more centered between the axles, the more likely to hit something. That said, our 2" exhaust pipe runs lengthwise from the OEM AC condenser compartment to just in front of our drive axle (under all 3 baggage bays) and has not hit anything. If you enlarge the photo below of our ProHeat exhaust, you can see the generator exhaust pipe in the background.  I don't know how "off road" you travel, but we frequently end up driving through cow pastures (some still have fresh cowpies)to a couple Bluegrass Festival sites.  Jack

[Lin]

Jack,

It is hard to tell from your picture, but it looks like you have a bolt coming through with the nut on the low end of the top hat channel.  The PO had done this with our generator and it began to cave the channel in.  We had to modify it to return it to a good grip.

[JackConrad]

Jack,
It is hard to tell from your picture, but it looks like you have a bolt coming through with the nut on the low end of the top hat channel.  The PO had done this with our generator and it began to cave the channel in.  We had to modify it to return it to a good grip.

   Lin, good eye to notice that.  Yes, that is one of 4 bolts that hold the ProHeat in place. The nut in the photo has Lock-Tite on it. Since the ProHeat is not very heavy, sits directly on the floor, does not vibrate, and all lines attaching to it (except the exhaust pipe through the floor) are flexible rubber with slack in them I was not to worried about it.  Jack
   

[rusty]

  When I ran my exhaust on my 13.5 k generator I first ran it under the bus into a flat muffler then about a 10 foot loop. I than ran  the 1 1/2" pipe up thru the bus inside a 4" double wall vent pipe. The vet pipe never gets any warmer than the surrounding temp. By running it under the bus fist it cools it considerbly before it enters the bus. I have been driving the bus for 5 years and have never hit the exhast under the bus.
                                                                                                               Wayne

[H3Jim]

The muffler is just in front of the duals, hanging from the bus frame via rubber mount and its about a foot higher than the bottom of the coach.  right on that side, also just in front of the duals, I have a 4" dump.  The dump hangs down below the bottom of the coach, so I didn't use glue on the elbow, I just clamped it.  This way it can rip out, if I hit something and all I have to do is put another one in.  I have ripped it out twice.  It ended up being at a transition from pavement to dirt, and there was a little dropoff at the dirt.

The exhaust piipe would be smaller than the 4" of course, and could be mounted much more solidly.  Although with the weight of the bus, I'm not sure anything could be made strong enough to keep from being ripped out.

Maybe I should Take RJ's driving course instead )

I talked to Dick Wright today about his ideas for an internal exhaust stack.  He said that Marathon useed to make them internal, but really did them overkill.  They used solid pipe all the way up, and used black pipe, connected directly to the exhaust, no mixing of air.  Then they put the high temp wrap around the entire thing, then another thin wall pipe, then more wrap, then air space, then another thinwall pipe, then more wrap.  There was airspace between one of the wraps and the outside pipe, and this airspace was open at the top and bottom.  They used the solid pipe to reduce exhaust noise inside the coach.  Then entire thing was about 12" in diameter.  It had a custom vent on the top that looked like a pie pan with louvers and pipe coming out the middle.  He said they finally stopped doing the internal runs due to liabilty concerns, although Dick did not know of any that ever burned up from the exhuast.  He cautioned me that many wood products will catch on fire at 250 degrees or so, and this is not out of reach for a fully loaded genset on a hot day, running all day.  Good point, but damn....

I think I may still run it up through the coach, but I really like the venturi idea that mixes cool air at the bottom along with exhaust gases as they rise up the pipe.  I would rather over engineer it than under engineer it, but their solution sounds so overkill as to be ridiculous - to me anyway.

[JackConrad]

Jim,
   A suggestion, if I can explain this.  Make a pipe like I use, only using 3" exhaust pipe (one piece/no joints) instead of PVC pipe, with the short piece of exhaust pipe centered in the lower end to get the cooling/dilution effect. Wrap this with heat wrap (although I have never had any spot on my PVC pipe so hot that I could not hold my hand on it). Then install a one piece 6 or 7" exhaust pipe down through the bus, sealed at the roof and at the baggage floor. This  pipe would be open all the way from the roof through the baggage compartment.  This pipe cound also be wrapped for heat and sound insulation.  Insert the 3" pipe inside the 6/7" pipe using stand-offs at the top and bottom to keep it centered. Let the 3" pipe stick up a few inches above the bus roof.  Add a cover at the top to prevent rain from getting down in the exhaust pipe.
   I saw a 1 piece vertical stack, that was a snup fit on the exhaust pipe, with no water drain at the bottom. After a hard rain, he started the diesel generator and spent the next several hours cleaning all the carbon mess of the side of his bus.  Jack