I finally got around to designing a homemade Genturi system. It is not installed yet, but will be in the next few days. Here is a partial shopping list:
1) 8' x 3.5" O.D. / 3.25" I.D. 6063 T52 Aluminum Tube:
http://www.onlinemetals.com/merchant.cfm?pid=18122&step=4&showunits=inches&id=278&top_cat=60
$61.61 Minus 10% with coupon code "Save10" = $55.45, plus shipping (our shipping cost was $17.40). Total was ~$73.
2) 1-3/8'' Galvanized Flat "Brace Band" - Round -- for chain link fence.
3-1/2'' Galvanized Beveled Brace Band - Round (flat would be fine, but beveled was all they stock in the 3-1/2" size).
carriage bolt/hex. nut 5/16'' x 1-1/4''
http://www.hooverfence.com/catalog/cpage2.htm
3 @ $0.42 each
3 @ $1.25 each
3 @ $0.18 each
~~~~~
There are of course numerous sources for the above materials. I picked OnlineMetals and HooverFence after looking at several sites, but there may be (and probably are) better sources. I've never purchased from either company before, so no warranty expressed or implied.
I've already ordered the 3-1/2" tube, but may try to find the chain link fence hardware locally, because while the prices are fine, the shipping is a little pricey at ~$16. I'll make a couple calls and if I can't quickly find the bands close to home I'll go ahead and order from Hoover Fence.
I checked into the potential for corrosion from dissimilar metals (aluminum and zinc) and the consensus seems to be that the anodic index of each is close enough that it should not be an issue. I will have to place rubber splicing tape (or similar) around the vertical ladder tubing anyway, because it is only 1" diameter and the bands are 1-3/8". I may be able to find similar bands in a 1" size, but they will almost certainly not be as stout as the chain link fence hardware. Also, they may not be galvanized.
This method of attachment has a few advantages:
1) No damage to the coach or ladder -- no holes to drill, etc. The pipe/tube can be removed and leave no trace (although we plan to leave it in place).
2) Secure mounting. It is possible to mount the pipe to the wall, but it would have to be on standoffs to clear the upper and lower trim (where the tail/brake lights are) and to be secure would require locating the metal framework underneath, and drilling/screwing into that. The ladder is rated to support 225 lbs.
3) The bands can be rotated on the ladder to adjust the position of the exhaust tube relative to the ladder and coach before tightening them.
4) Chain link fence hardware is inexpensive and strong. I found some aluminum fence hardware, but not 3-1/2" (only 3" and 4") and since galvanic corrosion is not much of a concern, I'm going with the galvanized stuff. Aluminum bolts and bands would look better, but they are not as strong. The last thing I want is to see my shiny aluminum pipe rolling down an embankment behind us...
5) Installing the bands on the ladder immediately above the rungs will prevent them from sliding downward, even if they get loose. Of course, there's nothing to prevent the tube itself from slipping if the 3-1/2" bands get loose, but it can only drop a few inches before hitting the 90* bend of the generator exhaust pipe, which will be supported with exhaust hangers.
I chose the tube I purchased because 6063 T52 aluminum has a nicer finish than 6061 and is more corrosion resistant. 6063 is not as strong as 6061, but in this application strength of the tube/pipe is not a concern -- weight and cost are. That's why I went with the thinner wall (1/8") tubing, which equates to schedule 10 pipe, rather than schedule 40 or 80. The latter 2 are overkill, weigh more, and cost more (about $95 for schedule 40, not incl. shipping). 6063 is known as "architectural aluminum" due to it's more finished appearance
The 8' length is the longest section they offer. It is plenty long enough to extend well above the roofline and still drop down below the ladder so that the generator exhaust will not have to be extended up very far. I really wanted to keep it one piece. If possible I might have gotten it a few inches longer, but 8' will be fine.
Total cost should be less than the Camco Gen-turi system, and it will be (semi) permanent and much more durable. No setup and teardown.
Hopefully this will help others save some time and brain cells.
There are probably other methods that are as good or better -- I just figured I'd share what we came up with, FWIW.
1) 8' x 3.5" O.D. / 3.25" I.D. 6063 T52 Aluminum Tube:
http://www.onlinemetals.com/merchant.cfm?pid=18122&step=4&showunits=inches&id=278&top_cat=60
$61.61 Minus 10% with coupon code "Save10" = $55.45, plus shipping (our shipping cost was $17.40). Total was ~$73.
2) 1-3/8'' Galvanized Flat "Brace Band" - Round -- for chain link fence.
3-1/2'' Galvanized Beveled Brace Band - Round (flat would be fine, but beveled was all they stock in the 3-1/2" size).
carriage bolt/hex. nut 5/16'' x 1-1/4''
http://www.hooverfence.com/catalog/cpage2.htm
3 @ $0.42 each
3 @ $1.25 each
3 @ $0.18 each
~~~~~
There are of course numerous sources for the above materials. I picked OnlineMetals and HooverFence after looking at several sites, but there may be (and probably are) better sources. I've never purchased from either company before, so no warranty expressed or implied.
I've already ordered the 3-1/2" tube, but may try to find the chain link fence hardware locally, because while the prices are fine, the shipping is a little pricey at ~$16. I'll make a couple calls and if I can't quickly find the bands close to home I'll go ahead and order from Hoover Fence.
I checked into the potential for corrosion from dissimilar metals (aluminum and zinc) and the consensus seems to be that the anodic index of each is close enough that it should not be an issue. I will have to place rubber splicing tape (or similar) around the vertical ladder tubing anyway, because it is only 1" diameter and the bands are 1-3/8". I may be able to find similar bands in a 1" size, but they will almost certainly not be as stout as the chain link fence hardware. Also, they may not be galvanized.
This method of attachment has a few advantages:
1) No damage to the coach or ladder -- no holes to drill, etc. The pipe/tube can be removed and leave no trace (although we plan to leave it in place).
2) Secure mounting. It is possible to mount the pipe to the wall, but it would have to be on standoffs to clear the upper and lower trim (where the tail/brake lights are) and to be secure would require locating the metal framework underneath, and drilling/screwing into that. The ladder is rated to support 225 lbs.
3) The bands can be rotated on the ladder to adjust the position of the exhaust tube relative to the ladder and coach before tightening them.
4) Chain link fence hardware is inexpensive and strong. I found some aluminum fence hardware, but not 3-1/2" (only 3" and 4") and since galvanic corrosion is not much of a concern, I'm going with the galvanized stuff. Aluminum bolts and bands would look better, but they are not as strong. The last thing I want is to see my shiny aluminum pipe rolling down an embankment behind us...
5) Installing the bands on the ladder immediately above the rungs will prevent them from sliding downward, even if they get loose. Of course, there's nothing to prevent the tube itself from slipping if the 3-1/2" bands get loose, but it can only drop a few inches before hitting the 90* bend of the generator exhaust pipe, which will be supported with exhaust hangers.
I chose the tube I purchased because 6063 T52 aluminum has a nicer finish than 6061 and is more corrosion resistant. 6063 is not as strong as 6061, but in this application strength of the tube/pipe is not a concern -- weight and cost are. That's why I went with the thinner wall (1/8") tubing, which equates to schedule 10 pipe, rather than schedule 40 or 80. The latter 2 are overkill, weigh more, and cost more (about $95 for schedule 40, not incl. shipping). 6063 is known as "architectural aluminum" due to it's more finished appearance
The 8' length is the longest section they offer. It is plenty long enough to extend well above the roofline and still drop down below the ladder so that the generator exhaust will not have to be extended up very far. I really wanted to keep it one piece. If possible I might have gotten it a few inches longer, but 8' will be fine.
Total cost should be less than the Camco Gen-turi system, and it will be (semi) permanent and much more durable. No setup and teardown.
Hopefully this will help others save some time and brain cells.
There are probably other methods that are as good or better -- I just figured I'd share what we came up with, FWIW.
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