There are a few considerations in your selection of a CO Alarm
besides the ratings by the UL.
CO alarms are either rated for unconditioned spaces and marine/RV
use or not. CO alarms have a maximum 5 year life and should be replaced every
five years at a minimum.
Read this article for more on the difference between old CO detectors,
and the current CO alarms.
First let me explain
the UL Rating for RVs. What it involves is separate testing for unconditioned
spaces, which costs the manufacturer thousands of bucks or more to have conducted to get the rating. By unconditioned spaces they mean extremes of heat and cold, because a majority of RVs are stored in the
winter by the owners, and even fulltimer rigs may spend a year or more on a lot with no A/C in summer or heat in winter. Thus the extra tests for certification for RV use.
They also, depending on the rating sought, have to stand up to extremes in temperature, vibration, cooking fumes,
shock, humidity, salt water spray, corrosion, and "take a licking but keep on ticking."
I have been researching CO issues and CO detector/alarms for the
past two years, and have found alarming emerging research that even low level CO concentrations well below the thresholds
that current CO alarms will alert at can cause severe health and neurological problem over time. It is called chronic low level CO poisoning. I bring the issue
up to support my next statement.
You want a CO detector that has an LCD readout, and will measure
CO Below 10 PPM, even if it does not alert at those levels. The reason I say
that is that on mine, I can press a button that will give me a readout of the current CO level in my rig, then reads out the
peak concentration over the life of the battery, then an estimate of the Carboxyhemoglobin levels at the current reading.
But mine is not rated as UL approved and tested for RVs.
You'll note that the Atwood is battery operated now, and so is
mine. The Atwood will measure low levels of CO where many others will not, and
has an LCD readout.
I at first thought that I wanted a 12 volt permanently installed
CO alarm but found that the portable unit can also act as a sniffer, as you can move it around to find the source of any high
levels of CO in your rig should the readings increase.
The EPA has changed their recommendations for CO exposure in the
last couple of years to no more than 9ppm over eight hours. Normal indoor readings
of between 5 and 10ppm with no unvented heaters adding to the CO inside is pretty much a normal reading.
Above 10-30 ppm over long periods of time, some pregnant women,
people with heart lung or circulatory disorders, and young children, can experience from temporary to permanent symptoms. At prolonged "chronic" exposure to 30 ppm or more neurological damage can occur, depending
on the susceptibility of the individual, age, and health.
We have experienced peaks of 30 ppm with no heater running, and
no cooking or other combustion occurring, after just few cigarettes have been smoked inside.
Ventilating took ten minutes or more with a fantastic fan.
So while your Kidde detector may work fine in your rig, it is
not UL approved for RV use. The one I am testing is not RV approved either, but
has worked fine. However, on the road, the peak readings can be higher than normal.
It will surprise most folks when they take regular readings of
indoor CO pollution with an accurate detector.
So regardless of which detector you select, make sure it reads
real time CO levels, and be aware that they do not alarm with CO levels below these ppm times of exposure:
After Oct. 1, 1998, UL 2034 listed CO alarms must measure and alarm when CO
30 PPM for 30 days
70 PPM for no more than 240 minutes before alarming (may alarm
as early as 60 min.)
150 PPM for no more than 50 minutes before alarming (may alarm
as early as 10 min.)
400 PPM for no more than 15 minutes before alarming (may alarm
as early as 4 min.) and have a manual reset that will reenergize the alarm signal within 6 minutes if the CO concentration
remains at 70 PPM or greater.
The above chart is from this very good article from the Bachrach
The choices and approximate prices for CO alarms that ARE approved
for RV use by UL testing, rated in my order of preference, your preferences may differ.
alarm - around 50 dollars. LCD, reads from 0 ppm on up. Has new technology sensors. Portable. Best buy in my opinion for an RV UL approved detector.
not measure low levels of CO, has no readout. For low levels of CO, will only
give a series of beeps which only lets you know there is/was less than 100ppm of CO.
CCI RV CO Alarms. No
price known, no read out, no levels of detection or ppm readings given
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. I have to say here that while I am testing the standard one, a case can be made for the low level programming
for alarming when used in a confined small space like an RV. Mine will only alarm
at the current UL standards. But if you are in one of the high risk groups for
low level CO chronic poisoning, they may be a good bet! They charge more because
of the proprietary programming. Once more, just because they say they are ideal
for RVs, they ARE NOT UL APPROVED FOR USE IN RVS. I include them so you know
what approvals they do have, and because they may be useful for high risk groups at their own risk.
Here is the one I have, it alarms at UL standards, is UL approved
for residences only, not RVs. It has an LCD readout, measures from 1 ppm to 500ppm,
gives real time current CO levels, and peak levels. About $60.00.
Aero Medix detector. Same
as above but alarms at 10 ppm. Same sensors and mechanics/electronics, made by
the same company.
CO Experts detector from $100-189.00 Same as above but alarms at 10ppm etc. Same sensors and mechanics
and made by the same company in Canada.
If you want the battery operated detector you need to get it from
one of the three US distributors above, but here is the manufacturer in Canada and the same unit with the same programming
This one is 115 volt but you’ll note the identical faceplate
Further reading and links for those wanting the full story
Most concise and comprehensive article albeit long
New Ul standards for 2003 CO detectors Big info! Cell phones cause false alarms it is at the bottom.
Here is a site with a lot of information on chronic low level
CO illnesses, with a lot of case studies at the bottom of the page.
From the Illinois State Fire Marshal website:
"Now, an emerging body of evidence suggests that longer exposures
to lower levels of CO, ie. chronic CO poisoning, are capable of producing a myriad of debilitating residual effects that may
continue for days, weeks, months and even years. Keep watching this site for new information on this topic."
Page on Chronic CO
poisoning with emerging evidence
Excellent and concise page that explains why the current crop
of CO detectors do not alarm at low levels, what types there are available, and why a low level detector that will sense as
low as 10ppm may be a life/health saver. Go here and read all of the topics at the top and you will have the best and most
concise understanding on the net.
Great page on UL standards and why the detectors are a first line
of defense, albeit the technology is severely lacking .