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Author Topic: Is freon supposed to register on a CO detector?  (Read 2814 times)
gumpy
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« on: June 15, 2006, 05:11:16 AM »

Ok, this came up last year on my trip to WY, and I had a suspicion. Now, I think I may have figured out a big piece of this little puzzle.

Last year, my hard wired RV CO detector started going off in the middle of the night, for no apparent reason. I suspected maybe a leak in the Aquahot exhaust. The bus engine wasn't running, and hadn't been for several hours.

So earlier this week, with the bus parked in the driveway, I turned on the basement A/C to cool it down inside so I could rewire my fridge's defroster circuit (another puzzle for another thread).  I left it running for a time, and came back out to hear the CO detector going off. I disconnected it.

Last night, my daughter wanted to have a sleepover in the bus, so I turned on the A/C for them, and plugged in a Nighthawk household CO detector I have. I came out about 2 hours later, and it was registering 122 on the readout. Turned off the A/C and opened the power vents and the reading started to come down immediately. This morning, the reading was 0.

It's obvious now that the problem is occurring because of running the A/C. Now I know the A/C doesn't produce CO, and there's no combustion going on anywhere. The AquaHot is turned off. The bus hasn't been run for several days. The propane is turned off, so no stove. It has to be coming from the A/C.

That leave me to believe there may be a small freon leak in the Coleman Basement A/C, and the freon is being detected by the CO detector.

Has anyone else experienced this? 

Nick, do you know anything about the freon used in these Coleman dual compressor systems (probably R22. Maybe R134)?



craig
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Craig Shepard
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« Reply #1 on: June 15, 2006, 05:48:18 AM »

Craig,

Do you have a propane 'fridge?  Sometimes, if it's not sealed really well and if there's a leak in the supply duct work, outside air can be drawn in.  If the air being drawn in is from around the 'fridge or its vent, you could have CO coming inside.  It's just a thought, but I had a duct leaking in my crawlspace at home and it would cause air to be pulled in from leaks around windows, doors, range hood, etc when the HVAC was on.

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« Reply #2 on: June 15, 2006, 05:56:28 AM »

Depends on how a CO detector works, which I am unsure of.  Does it measure the presense of CO or the absense of O2.  If the later, any gas that displaces oxygen could set off a CO detector.
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gumpy
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« Reply #3 on: June 15, 2006, 06:18:08 AM »


Do you have a propane 'fridge? 

No, 120v. Only propane is the stove, and the bottles are shut off. No combustion at all going on in the coach.
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Craig Shepard
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gumpy
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« Reply #4 on: June 15, 2006, 06:19:54 AM »

Depends on how a CO detector works, which I am unsure of.  Does it measure the presense of CO or the absense of O2.  If the later, any gas that displaces oxygen could set off a CO detector.

Interesting concept. I don't know the answer. I'll have to do some checking.

I assumed it was detecting the presense of CO.

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Craig Shepard
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« Reply #5 on: June 15, 2006, 06:34:38 AM »

Many CO detectors are clearly marked "not for RV use" - is yours ??
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gumpy
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« Reply #6 on: June 15, 2006, 07:54:09 AM »

Many CO detectors are clearly marked "not for RV use" - is yours ??

Well, I'm gonna guess that the hard wired one which was purchased through Coast RV Supply and is made specifically for RVs is probably not marked that way.

I don't really know about the Nighthawk, but I seriously doubt it knows whether it's plugged into a house or an RV sitting in my driveway.

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Craig Shepard
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gumpy
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« Reply #7 on: June 15, 2006, 09:27:50 AM »

Update. 

My wife just called and said the CO detector was up to 98 and blasting it's warning. The A/C hasn't been turned on since last night, but the vent has been closed since about 3 am when it rained.

I found some stuff online which indicates the older CO detectors (of which this is one) can be cross-sensitive to other chemicals, and freon was one of those. It also said that humidity affects the sensitivity and higher humidity (like today) can result in more false alarms.

I really think there must be a freon leak in the A/C, though, that is being detected by the CO detector. The RV CO detector was plugged in for a several weeks, including a trip to WY a few weeks ago, and it didn't have any problems until I turned on the basement A/C the other night (didn't use the basement a/c on the trip to WY).

I know a couple guys who work with a/c. Maybe one of them has a freon sniffer.

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Craig Shepard
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« Reply #8 on: June 15, 2006, 10:05:47 AM »

Craig,

Your basement air has a drain pan in it that is holding a certain amount of still water in it, that water has a mixture of dust, algie, and
some mold that produces small amounts of gasses. Theese gasses are then picked up by your blower and sent through the coach.
They are not harmful unless you have large signs of mold!! Than a good bleaching would cure that.
That is one of the reasons that home CO detectors don't work in small places.

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« Reply #9 on: June 15, 2006, 10:32:50 AM »

Nick,

The thought of something growing in the A/C evaporator area had actually crossed my mind, but I couldn't figure out how it would set off the detectors. Production of methane could certainly explain it, as I think that may have been one of the things the detectors can be overly sensitive to.  My other thought was possible outgassing from the Polyiso insulation, but that's been in for some time, so shouldn't be giving off much of anything anymore.

So evidently, the RV detectors are no better at filtering that stuff out than the household models are because my RV unit was alerting on it too.

So, would squirting some clorox into the evaporator help, or would that just create chlorine in the air which would also set off the alarm.

It seems that while it was a great safety idea, CO detectors (even the RV model) are probably not suited for the bus.

craig
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Craig Shepard
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Nick Badame Refrig/ACC
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« Reply #10 on: June 15, 2006, 11:16:19 AM »

Craig,

Clorox Cures everything!! Ha! Ha!

We use clorox on Duct work, Drain Pans, and even on Duct liner [insulation].

Use 2parts water and 1 part bleach.

The air will clear out after 1 day.

Nick-
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« Reply #11 on: June 15, 2006, 11:44:37 AM »

I'll give that a try. Teri said it didn't smell in there, but was starting to trigger her asthma, so could very well be this.
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Craig Shepard
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« Reply #12 on: June 15, 2006, 12:14:13 PM »

Craig,

So what you really had was an asthma Detector installed in your bus!!

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« Reply #13 on: June 15, 2006, 12:21:54 PM »

Yeah, maybe. The mold detector unpluged  it this morning, though.

The mold detector is typically installed in the copilot seat when traveling. Cheesy

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Craig Shepard
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« Reply #14 on: June 15, 2006, 01:36:14 PM »

Over the years I have seen some odd things with CO detector and eveb smoke detectors to some extent.

When Luan paneling was prevalent in RV's and van conversions some of the chemicals used in the manufacture
of the paneling would leech out and into the air and actually trip detectors.

Paints, Stains, Varnishes, sealants spray foam and canned foam can all leech fumes into the air which could
be detected by those electronic noses. Even cleaners like Chlorox Cleanup leave a residual smell and potentially
can leech into the air in a confined space. Automotive fabrics also leak chemical vapors, that's that new car smell!

My trick to solving that mysterious CO detector "creep" was to run a small ventilation fan to keep the air changed
on a continuous basis. I left my range hood fan on for 6 years. when I turned it off for 12 hours the invisible
CO "creeper" would start counting up. I found that something like 100 cuft/hour was enough to keep the detector
from counting and alarming.

Also if it is mounted on a wood surface might I suggest that you get a small sheet of plastic or mylar and insulate
the detector away from direct contact with painted/stained or laminated surfaces.

Just something that I had discovered.. Hope it helps..
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« Reply #15 on: June 16, 2006, 05:19:41 AM »

So, last night, I went out and turned on the A/C, and with a spray bottle of clorox solution, I sprayed a mist into the evaporator intake, and let it get sucked into the evap. It improved the smell inside the coach. Now it smells like a swimming pool! The a/c ran for about 3 hours and the co detector only went up to 9 before I shut off the a/c. Didn't look this morning to see if it went higher afterward. Will be able to check peak levels later on.

I'm not completely convinced it's microbe farts that are causing the co detectors to go off as the a/c is used infrequently, and in fact hadn't been used for several months, so would have been completely dry when I turned it on the first time this summer, yet that one time was enough to set off the RV co detector. Maybe there's spores or dust or something in there that wintered over and somehow the detectors are picking up that.

There's no possibility these alerts are caused by actual CO being detected, so I've come to the conclusion that the CO detector in the RV is probably not going to work. I'll leave the RV model installed, but will will certainly install a cutoff switch so I can turn the damn thing off when it alerts. It was designed to be hard wired. I had to cut the wire at 3 am last year when it wouldn't shut up. I'd prefer to have one in for the winter use when I'll be cooking and  heating the interior with it closed up.

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Craig Shepard
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« Reply #16 on: June 16, 2006, 06:48:22 AM »

Found the following info on-line. Hope it is helpful ..

Most CO sensors use a tin(IV)oxide semiconductor device.  When heated
and exposed to a reducing gas the conductivity increases.  Early sensors
were heated to about 300 C and were not very selective for CO since they
also responded to hydrocarbons.  Variations of this device are used for
explosive gas detectors (methane, propane etc.)  and breathalizers for
alcohol.  Newer CO detectors run at 80 C for most of the time which
eliminates false triggering, however crude builds up on the detector at
this temp, so they are programmed to heat to 320 C every so often to
clean themselves.  During this time they are inactive, which isusually
not a problem since CO usually builds up slowly.
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« Reply #17 on: June 16, 2006, 05:54:48 PM »

Found the following info on-line. Hope it is helpful ..

Most CO sensors use a tin(IV)oxide semiconductor device.  When heated
and exposed to a reducing gas the conductivity increases.  Early sensors
were heated to about 300 C and were not very selective for CO since they
also responded to hydrocarbons.  Variations of this device are used for
explosive gas detectors (methane, propane etc.)  and breathalizers for
alcohol.  Newer CO detectors run at 80 C for most of the time which
eliminates false triggering, however crude builds up on the detector at
this temp, so they are programmed to heat to 320 C every so often to
clean themselves.  During this time they are inactive, which isusually
not a problem since CO usually builds up slowly.


Actually that would explain why the CO detectors and for that matter even Propane leak detectors
might false alarm...
hydrocarbons

Hydrocarbons are contained in most products except maybe Latex paint. Wood preservatives, Paints, Stains, Varnishes and most Polyurethane sealants, Sikaflex, and many items. The outgassing we may not notice because we get used to the odors but they are there. A closed environment such as a bus or rv with a limited air flow and fixed volume allows the smallest amounts of the released gasses to build up over time.

These odors or gasses are usually ignored by the human nose after exposure. It's like you don't notice how bad the bathroom smells after a big stinky until you get into fresher air. It's not that the human body doesn't detect it by smell but it can detect things that we are unaware of and respond by allergic reaction or even athsmatic responses.

I am severely sensitive to molds as is my wife. I can smell certain molds in a matter of seconds long before other people even notice, I start reacting within minutes and the results are not good. My wife just went through the allergy testing and when they hit the black and brown molds she nearly went into anaphylactic shock with a couple of hours.

Please be aware that cleaning products can cause not only air quality problems but after long exposures you can become allergic to even the faintest of odors. My nemesis is Chlorox Cleanup.with Pine sol a close second. This I discovered after doing extensive cleaning to eliminate mold and now I am allergic to the cleaning products smells.

I guess I got off the topic slightly, Sorry.. But after living is a decidedly moldy or cleaner saturated environment ( My old RTS ) I developed a few more ailments. I just added that because I think that its possible that the electronic detectors that we rely on to monitor our environments may also be reacting to odors other than specifically intended.

 Undecided
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