Profiteer
Utah
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Joined: 11/03/2007
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pnichols.. are you sure it was not the stink of the Great Salt Lake that set your alarms off? At 95+ it can get pretty rank..! Ha ha
Sorry... I just had to toss that in. I live in UT and on a really hot day with the wind blowing just right.. OH WOW... LOL
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pnichols
Santa Cruz Mountains
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Joined: 04/26/2005
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"..are you sure it was not the stink of the Great Salt Lake that set your alarms off? At 95+ it can get pretty rank..!"
Yeah .... good point!
As a test I ran the AC at full bore today in the back yard off the Onan for well over an hour with the front fan on high - to pull fresh air through the rig from the rear vent to duplicate our camping situation - with no problems whatsoever.
One thing that could have caused it was perhaps a little known, or at least used, adjustment on later model Onan generators: The altitude adjustment for leaning of the air/fuel mixture. I think the Salt Lake area is at about 4200 feet but unintentionally I had left this adjustment on the Onan set at sea level. I think that an engine running rich like this can put out more fumes and odor without any noticeable increase in visible black smoke from it's exhaust. Maybe this was causing it's exhaust to be more "pungent" - hence the odor and triggering of the propane detector.
Phil, 2005 E450 Itasca 324V Spirit
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TomW2
Southwest Washington State USA
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Joined: 05/23/2005
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pnichols wrote:We had the bathroom vent open (but with it's fan off) and the cabover vent open with it's Fantastic fan on low pushing air out in order to pull fresh air from the bathroom through the rig at all times while the AC was running.
Right there was your problem and using a genturi while doing the same thing won't fix a thing and could even possibly make it worse.
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pnichols
Santa Cruz Mountains
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Joined: 04/26/2005
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"Right there was your problem and using a genturi while doing the same thing won't fix a thing and could even possibly make it worse."
The bathroom vent is way at the back and the cabover vent is of course way at the front - both way above the Onan's exhaust pipe. The Onan exhaust pipe is about 2/3 rd's of the way between them towards the front and of course way down low at the bottom edge of the coach's sidewall with the end of the Onan exhaust pipe portruding out the sidewall by about the required/recommended 1 1/2 inch.
I'm of the opinion that one should NOT ever operate their onboard built-in generator for long periods with the rig completely sealed up .. no more than one should live in their rig under any other conditions with it completely sealed up. Hence, I was trying to establish some air flow - drawn in on the roof and expelled on the roof via the front vent fan and way above the Onan's exhaust outlet - while the Onan was running the A/C. I knew the A/C could more than compensate for this warm outside "fresh" air flow by still cooling the coach area fast. By using this combination, I was attempting to achieve both interior cooling and fresh outside air safely circulating. It seemed right to me.
I'm wondering if Profiteer didn't nail it, above: "pnichols.. are you sure it was not the stink of the Great Salt Lake that set your alarms off?"
Perhaps my circulating air system merely was bringing in Great Salt Lake stink to set off the "propane" detector while also being so pungent as to be mistaken by us as "Onan exhaust" smell? I've had problems in the past with our propane detector nuisance alarming from perfume, hair spray, human gas, etc. ... and read plenty of stories in this forum about strange odors setting off RV propane detectors. I'm beginning to think that propane detectors are NOT designed to be sensitive to propane gas itself, but to be sensitive only to the odor agent that is put into propane. Ultimately not the optimum design, IMHO, as they should be sensitive to the propane mulecule itself - not some odor agent that can easily be coming from other sources.
I'm thinking of, painfully, springing the $60 for another propane detector even though mine is only about 3 years old. I wish there was some way to really clean out these detectors thoroughly to make them less trigger happy ... or at least readjust their sensitivity somewhat.
* This post was
edited 08/19/08 03:40pm by pnichols *
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tom1984
Olive Branch,Ms
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Joined: 08/07/2007
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Quote:I'm of the opinion that one should NOT ever operate their onboard built-in generator for long periods with the rig completely sealed up
I would never operate my gen any other way. If you are using a fan to pull in "fresh air", the main thing you are going to pull in is generator exhaust. Always have a carbon monoxide detector and it doesn't hurt to have 2.
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pnichols
Santa Cruz Mountains
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Joined: 04/26/2005
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"If you are using a fan to pull in "fresh air", the main thing you are going to pull in is generator exhaust."
Tom, I guess I don't understand what you are saying.
If the intake of your fresh air is well away from your genny exhaust - as mine is both in straight line distance and height difference - then I don't see an issue.
If I installed a Gen Turi then you're correct, if I understand you, that I should not open any roof vent as the Gen Turi of course exhausts up high above the roof where the roof vents are.
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tatest
Oklahoma
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Joined: 05/14/2005
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pnichols wrote:... I've had problems in the past with our propane detector nuisance alarming from perfume, hair spray, human gas, etc. ... and read plenty of stories in this forum about strange odors setting off RV propane detectors. I'm beginning to think that propane detectors are NOT designed to be sensitive to propane gas itself, by to be sensitive only to the odor agent that is put into propane. Ultimately not the optimum design, IMHO, as they should be sensitive to the propane mulecule itself - not some odor agent that can easily be coming from other sources.
The propane detector is a total hydrocarbon detector. It measures infrared absorption at a wavelength corresponding to a single C-H bond. This works to pick up all the flammable fuel gases, but there are a whole lot of household chemicals (equally flammable) that also have this bond.
Almost anything aerosol will set off the detector, because propane is used as a propellant in almost every non-food aerosol can. You want it to detect the propane from your tank, but not the propane in the hairspray? Not possible.
To tell one hydrocarbon chain from another, i.e. pick out propane and nothing else, you would need a gas chromatograph (tens of thousands of dollars) and a much richer gas sample than you ever want to see inside a space you personally occupy.
Tom Test
Itasca Spirit 29B
2001 Ranger Edge
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