Bill: I saw your modesty in your post and if someone can show me how to edit (or maybe Bill NY can do it) I will remove the reference. Done by Rusty

HOWEVER - adapting to readily available materials and techniques is but one way to achieve a US Patent, so guiding us to the proper sizes, materials and most of all the spacing of the Venturi is, it seems to me, original thinking. I could not have made mine without your post so just let me say THANKS!

I am a brand new Motorhomer and just stumbled onto this forum wanting to find out about what a Genturi was! I feel like a complete moron. You guys are contemplating the finishing touches of Saturn Rocket tech on an exhaust system! I have a lot to learn. Just bought a 2003 HR Endeavor and going through the motions. Havent ventured out to a state park or two just to get my feet wet. Good that I like Lowes. Now Im going to have to hit up my father in law and try to get him to venture into his shop and make an exhaust system like the ones you are designing. My generator is loud but I havent attempted to do anything yet since I really dont know what Im even doing yet. Looking forward to seeing some of the country and figuring out how not to be too surprised when something goes amiss. Thanks for letting me drop in. Bill, Ronda and the trips - Nicholas, Ashby and Henley!!!

Welcome to the forums! Both bill h and I have cobbed togethe Genturi clones. While we both pulled some material from the scrap box, a clone can be made for <$40.

So Im gonna be doin some dry camping at a couple of races soon - i thought id be a good neighbor and build a genturi generator exhaust stack.

I've seen several references and photos - i followed them and im a bit shocked at the temperatures that im seeing....no where can i find any temperature measurements.
CLEARLY PVC can NOT be used because of its melt point - and i cant imagine Cpvc being any better.

Im using 2 inch PVC - will 3 inch make that much of a difference (lower temp) ??

Anyone have any opinions or experience ?? Is the REAL (retail) camco GenTuri made of aluminum ??

heres some photos - 1st one is just a mock up (before i set the air gap at 2 inches - like the manufactured units)



in this photo - the aluminum collar is only 115*, while just a few inches above it - the 2" pvc is 166*

I have just begun building my own following the design laid out throughout this topic. I have found the collective wisdom here to be a huge help.

I do have a question about support. I have not actually attached the venturi to my coach due to foul weather, however, I am concerned about the weight resting on the exhaust of the genny. I have an Onan Marquis 5500 and while the 3" thin wall doesn't weigh much, the stock exhaust is not designed to support much of anything. Does the suction bracket provide much vertical support? I see how it prevents lateral movement, but it does not look like it holds any of the weight. Am I mistaken? Has anyone made any modifications to address this issue?

Dave Eroh
Grateful Non-Barth Owner

quote:

n the exhaust of the genny. I have an Onan Marquis 5500 and while the 3" thin wall doesn't weigh much, the stock exhaust is not designed to support much of anything. Does the suction bracket provide much vertical support? I see how it prevents lateral movement, but it does not look like it holds any of the weight. Am I mistaken? Has anyone made any modifications to address this issue?

dave - if you mount the suction cups (or what ever you use) such that it pulls UP on the pipe you can easily eliminate most of the weight that would be pushing "down" on the gen stock exhaust.

btw i was never able to get this to work - i tried several different material types and thicknesses - ALL of them got too hot some even collapsed the pipe, no amount of adding or decreasing the air gap changed the end results for me.

I wound up buying a genturi - its got to be made of something other than pvc...its held up very well in comparison...and it NEVER gets soft (like the pvc's i tried).

I bought one of these from camping world a few years ago, and it works fine. Don't know what the stack is made from--it's about 3" in diameter and made from some kind of black plastic. It's supported by a couple of clips mounted to the side of the Barth.
Jim

Did you use 2" PVC for the final version too? I would think you'd need the 3" in order to draw in enough air to cool the stack pipe. A 3" has over twice the cross section, would draw in more air to dilute the hot exhaust stream.

What size is the purchased version?

i used 2, 3 & 4 inch and i tried thick and thin (sewer) wall pvc's - ALL got too hot & ALL had plenty of fresh air (suction)...EASILY pulling in and blowing out bits of paper towel.

my issue MAY have been the 10kw unit, i dont believe that ive seen anyone build one themselves with anything larger than an 8k.

Interesting... I have a 7 kw Kohler and I'm thinking of making one for it. You're probably right, the 10 kw is making a lot of heat. I may just use thin wall metal duct (aluminum) and live with the weight.

quote:

Originally posted by bushpilot:
i used 2, 3 & 4 inch and i tried thick and thin (sewer) wall pvc's - ALL got too hot & ALL had plenty of fresh air (suction)...EASILY pulling in and blowing out bits of paper towel.

my issue MAY have been the 10kw unit, i dont believe that ive seen anyone build one themselves with anything larger than an 8k.

I am hoping that being that I am only running a 5.5k that the heat will not be as much of an issue. I will be mounting and installing my homemade venturi this weekend and will get the first true test then.
I am considering reinforcing the bottom of the PVC where I have the bent aluminum that mates it to the electrical conduit 90° from the stock pipe. The walls are so thin that I am afraid it might crack with use not to mention the heat stress. My pipe that I found at Lowes has a greenish tint to it. Is that the variety most of you found?

quote:

Originally posted by Bounding4:
electrical conduit 90° from the stock pipe. The walls are so thin that I am afraid it might crack with use not to mention the heat stress. My pipe that I found at Lowes has a greenish tint to it. Is that the variety most of you found?

i used thinwall (sewer) pvc (3 inches) and it melted in about 15 seconds....the thinwall sewer pipe is probably the same as your green/gray thinwall.

if you have access to a laser/infrared thermometer id use it...itll save you a lot of trouble...if you have temps exceeding 120* youll likely experience melting...i wouldnt tolerate any SOFTENING of the pvc.

the best we can figure is that he GENTURI is probably made from some bake-a-lite type material...it does have some "fiber glass" like properties to it...and it amazingly enough iirc it never gets much over 100* at its hottest point and it never gets soft or shows any sign of softening.

I originally used hot water heater vent pipe - 3" double wall metal. I use now the 3" sewer PVC thinwall; it's run for hours with no issues.

quote:

Originally posted by bushpilot:

quote:

Originally posted by Bounding4:
electrical conduit 90° from the stock pipe. The walls are so thin that I am afraid it might crack with use not to mention the heat stress. My pipe that I found at Lowes has a greenish tint to it. Is that the variety most of you found?

i used thinwall (sewer) pvc (3 inches) and it melted in about 15 seconds....the thinwall sewer pipe is probably the same as your green/gray thinwall.

if you have access to a laser/infrared thermometer id use it...itll save you a lot of trouble...if you have temps exceeding 120* youll likely experience melting...i wouldnt tolerate any SOFTENING of the pvc.

the best we can figure is that he GENTURI is probably made from some bake-a-lite type material...it does have some "fiber glass" like properties to it...and it amazingly enough iirc it never gets much over 100* at its hottest point and it never gets soft or shows any sign of softening.

Well since I already have the thing built, I don't have anything to lose in trying it out. Worst case I wasted $35. I know that I should just bite the bullet and buy the brand version but I am stubborn and love to find solutions. Somehow the challenoddly making it work is oddly fun. Not necessarily guaranteed to be productive though.

I agree that nothing short of fully functional will be acceptable and a Venturi that is only slightly molten does not qualify. On that note, has anyone tried to add a section of something more heat tolerant at the bottom of the pipe above the exhaust to act as a heat sink or buffer?

I've been meaning to post this for a while and just haven't gotten around to it. I have a Genturi that came with my Barth and I never use it and would like to offer it to some one who will. There's not to many Barthers here in Mass. but it would be cool if I could just hand it off to some one and say enjoy. Also have 2 tag axle air control/guage assemblies
Lloyd