If you study the construction of the Gen-turi for awhile, it's very easy to fabricate your own.
I used a 10 foot length of 3" thinwall pvc. It comes with a swage on one end. I cut it to length, then cut it in half. The swage couples the two pieces back together and allows it to be stored easily. I used a 90 degree 1 1/2" conduit sweep slipped over the generator exhaust to point the pvc straight up. I drilled a hole for a pin through the conduit sweep and the generator exhaust to attach the stack. I used 3 short pieces of 1/2" copper water pipe attached to the conduit as spacers to attach the pvc. The hardest part was centering the drill over water pipe and drill through the pvc so I fasten it with a screw. You could eliminate that problem by attaching the pvc with external straps the way Camco does now. The distance the conduit sweep sticks into the stack is not important, just a long as it directs the generator exhaust into the pvc. You can get everything you need at Home Depot or Lowes, the cost is under $15 and your time.
There is plenty of dilution air drawn in around the conduit to keep the pvc from getting hot. I've never felt mine get much more than lukewarm even under a good load for several minutes. I hold it steady with some miniature bungee cords attached to the MH at the belt line in some hole I drilled on the underside of it so they wouldn't show. Suction cups will do a good job also.
At the last rally I attended, I was the only one using a stack (and the only gas rig around close). The diesel generators around me almost caused me to choke. The fumes were so bad from them. They all seemed to be pointing at us. My eyes burned and cussed them every time they turned them on. All that dough for a DP and they didn't seem to have enough left to buy a stack or they just weren't courteous enough to use one - I don't know what their problem was but, I was the one who suffered. I never use my generator for any length of time without the stack. The fumes always find their way inside without it.
DFord, when you say thinwall PVC, is there a spec or proper name for that? I think Schedule 40 is the thick stuff right? Also, do you know what wall thickness I can expect from on a 3" thinwall PVC?
Thanks,
Tony
Schedule 40 is a medium grade....there are many thinner products but dont now if Ive ever seen anything smaller in a 3" pipe other than ScH 40....smaller pipe comes in Sch 200, 125 ect ect and you can get thicker too with Sch 80. I do have the Genturi and I think sch 40 would work well.
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Don't use very thin pvc for your homebuilt genturi! I've been using one built out of 3 inch thinwall pvc sewer pipe, with a 2 inch metal conduit 90 degree sweep on an Onan 7.5 diesel genset. The remainder of the construction details were exactly like DFord's description above. Something about this combination did not work. It worked great during the late fall and winter. Two weekends ago in the very hot south Georgia sun with the genset running hard, the thinwall pvc began to get soft. It never failed completely, but got some new gentle curves in it.
Today, I built a replacement using 3 inch schedule 40 gray electrical conduit pvc. It is thicker than the previous sewer pipe, and has a temp rating of 90 degrees centigrade. I also used smaller 1 1/2 inch metal conduit for the 90 degree sweep, and fabricated a new bracket that looks like the commercial Genturi to hold the metal conduit to the pvc. I'm hopeful this one will survive the hot days.
Fred & Vicki
Richmond Hill, Ga
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I know what you mean. I was told they required Exhaust stacks on generators for camping in close quarters, but I bet out of 10,000 campers I did not see more than 1/2 a dozen. Most did not know what my Genturi was.
The wonderful guy behind me had a Contractor grade generator that he ran 24/7 (Even when it was in the 60's at night). He had it 3' off my back bumper with the exhaust pointing under my MH. Noise wasn't really a bother, heck, I have ear plugs and we're at the races right, so who cares.
The first couple of days, the wind was blowing so hard it didn't matter too much, but the third day, the wind died down to less than 5 mph, and every CO detector in my MH was going off. I asked politely if we could slide it over a little so the exhaust didn't go directly under my MH and he got a little chip on his shoulder. I helped him and we moved over a few feet and all was well after that.
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The thinner pvc is called DWV (drain, waste and vent) grade pipe. One end comes swagged (expanded to fit over the next piece instead of a requiring a coupling). The 90 degree 1 1/2" conduit sweep can be found in the electrical department. It's just big enough to slip loosely over my generator exhaust pipe. The sweeps come in 1 1/4" size also for smaller generator exhausts but I'm not sure I would go much bigger. The larger exhaust pipe will block the dilution air from easily entering.
My generator is 5500 watts gas powered. The dilution air is important to keeping the temperature of the pipe within reason. If you were to dump only the exhaust gas into the pvc with it, it would overheat in a short time. That's why there is a gap on the Gen-turi. On other models I studied, the exhaust pipe went inside the stack a very few inches but had a gap around it (I used the 1/2" copper water pipe because it was handy, the commercial model used a square tube about the same diameter) and spacers to maintain the gap. The gap allows the dilution air to be drawn in.
The warmer gases inside the pipe draw cooler dilution air into the bottom of the pipe as they rise. This reduces the temperature and humidity of the gases inside the pipe and helps reduce condensation.
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