Carbon Monoxide Measurements - Fiberglass RV


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Old 03-01-2009, 06:50 PM   #1
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I installed a new Wave 3 catalytic heater in our Scamp 13 this winter, and just this weekend installed propane and carbon monoxide detectors. Both are Atwood units. The propane unit wires directly into the 12V system, so I installed it on the front diagonal corner of the streetside bench, which facilitated connecting directly to the hot battery line. The carbon monoxide unit, using internal batteries, I mounted on the rearward facing side of the closet, up fairly close to the ceiling. Just to give the complete picture, the heater is mounted below the closet door as many others have done.

I recall others stating that opening the ceiling vent a half-inch and the side window over the stove an inch or so will provide sufficient ventilation. I think that comes from quidelines the Wave 3 folks show in terms of square inches of vent area, which I'll go back and check. So, much to my surprise, with the heater on high the digital display on the CO unit indicated as high as 95 ppm. According to the Atwood manual, that will result in a mandatory alarm within 60 to 240 minutes. Alarm or no alarm, it's too high. I took the unit out into the garage (Scamp is garaged for the winter) and the reading quickly returned to 0. Increasing the ventilation a little more resulted in a reading closer to 60 ppm, which is just below the alarm threshold. With this same amount of ventilation and the heater output reduced to low, the reading dropped to 0.

So all this is telling me that having a CO detector is really important, and that any time we run the heater on high, it's going to take a lot more ventilation to remain at safe levels. This is possibly a multi-variable problem, since the heater is also depleting the oxygen content of the air in the Scamp, but either way, it indicates the need to be really careful with providing adequate ventilation. I'm going to experiment to find out how far I need to open the top vent and the stove window to keep the CO level at 0 with the heater on high, but I doubt we'll ever go to bed with the heater on high. Low...maybe.

Parker
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Old 03-01-2009, 07:16 PM   #2
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Very interesting test you did....I will be keeping an eye on future tests you do as i also have a wave3 catalytic
Joe
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Old 03-02-2009, 09:52 AM   #3
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For what it is worth, my experience with the Atwood carbon monoxide alarm: The unit seemed to get set off by whatever off-gassing that is left in our 9-year old trailer (!) so I removed it. As the ambient temperature increased so did the apparent off-gassing. That was without any propane or combustion going on at all.
I drew on the experience of my fireman brother in law who opined that these units are much too prone to erroneous readings to be relied on, so I removed it to get rid of the nuisance alarms.
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Old 03-02-2009, 02:26 PM   #4
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So, much to my surprise, with the heater on high the digital display on the CO unit indicated as high as 95 ppm. According to the Atwood manual, that will result in a mandatory alarm within 60 to 240 minutes. Alarm or no alarm, it's too high.
Hmmm. That's very interesting. Platinum catalyst heaters (like the Wave) shouldn't be able to make carbon monoxide at all, the reason being that the platinum catalyst grabs propane molecules and twists them so oxygen can jump in there and rob the propane molecule of its hydrogens, then pull the carbons away. All this happens in such a way that the propane molecules can't get loose from the platinum catalyst until combustion is quite complete. That's why automobile catalytic converters use platinum catalyst to reduce both hydrocarbon and carbon monoxide emissions. And since the entire catalytic process happens at a temperature that's below the heat required to burn propane, no additional partial compbustion events should happen that would create carbon monoxide, either.

We have a wave heater for our other trailer. I'll have to hook it up and do an experiment or two with a CO detector I have in the garage and the Wave 3 once we have it hooked up.
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Old 03-02-2009, 04:26 PM   #5
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We have a wave heater for our other trailer. I'll have to hook it up and do an experiment or two with a CO detector I have in the garage and the Wave 3 once we have it hooked up.
Peter,

That would be great. Perhaps the catalytic process just isn't perfect and is mixing-limited. Works great for all the molecules in contact with the catalyst, but not all molecules get the treatment? The readings could also be due to oxygen depletion, but the fix is the same....more ventilation. Unless of course there is something wrong with the (new) heater.

Here's a link to an academic paper on the subject:

http://www.cpsc.gov/LIBRARY/FOIA/FOIA05/os/CO03.pdf

The executive summary gets right to the result. My guess is it's oxygen depletion driving the process toward production of CO and maybe inaccurate readings to boot.

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Old 03-02-2009, 05:31 PM   #6
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That type of heater should not put out Carbon Monoxide so If it were mine, I would stop using it. As far as I'm concerned, Any Carbon Monoxide reading is too much to go to sleep with. Why take a chance with your life like that?

Go to BJ's Wholesale Club and purchase a Night Hawk KN-COPP-B with a LCD display and then do a recheck.

I have 4 of these in my house (basement, main floor and bed rooms) just incase one unit goes bad.
You don't wake up dead from carbon monoxide poisoning.


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Old 03-02-2009, 07:51 PM   #7
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Okay, I did another experiment. I opened the roof vent/escape hatch about two inches at the rear and opened the small stove window almost wide open. With the heater on high for a couple of hours, the CO reading leveled off at about 50 ppm. The Scamp is in the garage, so there was no wind to help with ventilation (which could happen in the wild as well). The garage is unheated....probably about 30 degrees out there right now. With that much ventilation, the Scamp wasn't all that warm inside! While I well understand the hazards of carbon monoxide, this level of CO is down into the no-worries category (but I still wish it read 0).

Here's what I think is happening. The heater consumes enough oxygen to limit its ability to created carbon dioxide, which is the desired product of complete combustion. With insufficient oxygen, some carbon monoxide is produced. If the heater was operating in a larger space, I'm sure it would not produce the CO levels I'm seeing. The big unknown in this is the accuracy of the detector in even a slightly reduced oxygen environment. I'm not sure what else to try at this point other than double-checking with another detector as Darwin suggested. My conclusion for now is to increase the ventilation while running the heater on high, and to sleep with it set no higher than low.

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Old 03-03-2009, 12:41 AM   #8
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Personally, I don't sleep with my unvented heater going (Non-cat with ODS sensor), nor would I sleep with RV furnace going, unless it was VERY cold outside -- Rather, I use my electric heater if I am on shore power or my good sleeping bag.

That said, these heaters shouldn't be producing any CO and I suspect something else is operating here. Don't forget that CO can be persistent, i.e., it won't necessarily disperse in the surrounding atmosphere -- Your garage may be a 'collection point' for some other source.

I recall a case of CO poisoning to a guy on another group living in an RV parked in trailer park (as opposed to RV park in that it was more permanent). He had a weekly card-playing group over and between them and a leaky RV furnace (loss of seal between combustion chamber and circulation chamber), he was getting CO that was built up. Fire department found his bathroom to have a high concentration long after card-players gone and heater turned off.
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Old 03-03-2009, 06:23 AM   #9
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Personally, I don't sleep with my unvented heater going (Non-cat with ODS sensor), nor would I sleep with RV furnace going, unless it was VERY cold outside -- Rather, I use my electric heater if I am on shore power or my good sleeping bag.
Pete,

In reality, that's how we'll operate most of the time. We were trying to set up for the occasional night when we don't have shore power available, want to have a little heat during the day for lunch if we're on the road, etc.

I still want to scope this out. I'd like to find out how accurate the CO detector is in the presence of water vapor, slightly reduced oxygen level, etc. I won't blow it off just because it's giving me a reading I don't like, because it could well be real. On the other hand, if this particular detection scheme is not the best for this installation, maybe some other unit would be better.

Parker


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Old 03-03-2009, 07:33 AM   #10
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No problem, I was just prefacing my comments with what I do for those who are concerned about the general issue, but not so interested in details.

I am indeed interested in your odd findings. CO is not only fatal in large doses, it's cumulative in small ones and can make one pretty sick without the cause being very apparent.

I recall back a few years ago, when the CO monitors were first coming out, that there was a vast price difference between home and RV units. At that time, there was speculation that they were set to different trigger points but can't recall which was more sensitive and why they chose to make it so.
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Old 03-03-2009, 07:57 AM   #11
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For what it's worth.

I asked the salesman at scamp about detectors and he said that they found the area to small. Made them too sensitive so they don't put them in anymore.

Bill K
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Old 03-03-2009, 08:05 AM   #12
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For what it's worth.

I asked the salesman at scamp about detectors and he said that they found the area to small. Made them too sensitive so they don't put them in anymore.

Bill K
Wow, that's really interesting. My Atwood unit is made by Kidde. The manual has a number to call with questions, so that will be my next step. I'll mention your comment to them.

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Old 03-03-2009, 11:25 AM   #13
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Bill, Most codes require new campers to come with certain detectors.

In my opinion, any camper manufacture that does not include detectors is a camper that you should not consider purchasing.

A small space will become deadly much quicker than a large space and the detectors are measuring parts per million and in my opinion it would be even more important to have the detectors in a small space.

Send them an Email question and then Post their reply so it is On The Record.
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Old 03-03-2009, 12:56 PM   #14
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Read this site for a lot more info -- CO detectors for RV use should be approved by UL, but most are not, even some that say good for RVs on the package (See quote below).

http://home.earthlink.net/~derekgore/rvroa...ylike/id87.html

I just read somewhere that 'UL-approved CO detectors are required in all new motorized RVs, as well as those new RVs equipped with generators' Tried to find it again and couldn't -- Thought it was in the link above, but can't find it agan, so I can't determine which agency set that requirement...


QUOTE
Of the non UL approved for RV alarms now on the market, I have only two alarms that several RVrs have tested and found satisfactory, and only one I have personal experience with. That is not to say that the other major brands won’t work. But I, nor the manufacturers, can or will recommend that you use a non UL approved for RV use alarm in any case. Use of an unapproved alarm is at the risk, both financially if it does not work, and a health risk if they fail.

The two are the Kidde Nighthawk, which I have no personal experience with in an RV, and another made by a Canadian firm in several different programming modes, one of which I have been testing now for six months with good results. They all have the same CO sensors, the only difference is the price, and the programming. Let me explain. These alarms are all made by a Canadian manufacturer, have LCD readouts, will give accurate readouts from 1 ppm CO on up. The one I have is the cheapest of the three identical detectors, and will only alarm at the UL standards given above. The other two are the CO Experts model that will actually alarm at low levels, (the different programming) and the Aero Medix. They will alarm at 10ppm on up, with different alarms for each level. However all three are not UL listed for RVs, despite the fact that they all claim they are made for the RVs.
END QUOTE

So, how much do you want for your 5W?
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