Dual CO & LP Detector

[kartvines]

I just bought a Atwood CO and LP detector, and I am now wonder where it should be installed to get the best safety benifits.

I have read somewhere that CO detector should be mounted higher up in the coach than the LP, so where should a dual unit be installed?

I keeping the stock LP detector in place because even though the detector no longer works, it still controls the LP valve, and I like the idea of shutting off from the inside.

[ksg5000]

My recollection is that technically CO is heavy and in theory you would put the detector low. Many people put it high next to a smoke detector probably because from a practical perspective CO is associated with things like furnaces which involve moving air which prevents the CO from settling. Probably no ideal spot given the combo. I keep a CO detector above our bed were we sleep - the propane detector is low in the stair/foot well.

[Hooligan]

Safe-T-Alert dual CO/LP alarm instructions:
Install near sources of potential gas leaks,- stove, furnace, refrigerator etc
At least 4 but not more than 20 inches above the floor.

DO Not Install, in a closet (duh), behind furniture or drapes. within 12 inches of windows, doors, heating or return vents, or drafty areas
Or on a circuit that can be switched off.

[Budz]

Dual alarm should be mounted from 4" to 20" from the floor. Near appliances. Safe T Alert model 70-742R Kit has a valve control feature (closes valve if gas is detected). UL no longer allows a manual shut off switch be part of a listed gas detector - safety issue.

[kartvines]

FYI it came yesterday and your information was good it states merely install the detector no more than 18" off the floor.

Thanks for the feedback

[PORCHDOG]

If I am not mistaken, Carbon Monoxide (CO) is slightly lighter than air whereas Carbon Dioxide (CO2) is much heavier than air. Liquid Petroleum Gas (LP) is heavier than air. That said, the location of a combination detector, (CO and LP) would be a comprimise. Mounting high to detect CO or mounting low to detect LP would be ideal. Mounting close to the floor would surely detect LP and if mounted a little higher than at the floor it would detect the LP and hopefully also detect the CO. Two separate detectors is without a doubt best. A CO detector on the ceiling and a LP detector at the floor level.

[4Knights]

Quote:

Originally Posted by PORCHDOG If I am not mistaken, Carbon Monoxide (CO) is slightly lighter than air whereas Carbon Dioxide (CO2) is much heavier than air. Liquid Petroleum Gas (LP) is heavier than air. That said, the location of a combination detector, (CO and LP) would be a comprimise. Mounting high to detect CO or mounting low to detect LP would be ideal. Mounting close to the floor would surely detect LP and if mounted a little higher than at the floor it would detect the LP and hopefully also detect the CO. Two separate detectors is without a doubt best. A CO detector on the ceiling and a LP detector at the floor level.

CO2 is what you exhale, CO is what comes from burning carbon based materials and sinks as well as LP. Both tend to stay below 18 inches from ground level, thus the detectors are kept lower than sleeping position air intake of people. Also the reason that most states adopted the requirement for all gas fed appliances in garages be mounted 18-24 inches off the ground in garages. Reduced the number of fires due to sparks and natural gas leaks.

[PORCHDOG]

I respectfully disagree with 4Knights on the statements he has made. Carbon Monoxide is slightly lighter than air (carbon monoxide's specific gravity is 0.9657, the specific gravity of air is one). Carbon Dioxide is approximately one and a half as heavy as air. Children learn from firefighters that they should stay low in a fire, out of the Carbon Monoxide which is poisonous.
The reason that all gas fed appliances in garages are required to be mounted 18-24 inches off the ground is that petroleum flammable liquid vapors are heavier than air and should a spill occur in the garage, the vapors will settle to the lower level. The flammable vapors will then come in contact with the flame from the heater. Natural gas is not the same as Liquified Petroleum gas. LP is heavier than air and natural gas is lighter than air.

[4Knights]

All you ever needed to know about carbon monoxide hazards. http://www.epa.gov/iaq/co.html

[ksg5000]

My 02. CO is close enough in weight to air that it doesn't really matter. Ideally you want a separate CO detector which is place above and near the source of CO. Above because the typical CO generating device is one that produces heat not because of the weight of the gas. With that said -- a combo detecting device should be placed low -- that's because the gas portion of the device needs to be low.

[Budz]

CO alarms are calibrated at 70 ppm, 150 ppm, 400 ppm. At 70 ppm they cannot alarm before 1 hour of exposure but must alarm before 4 hours. At 150 ppm they cannot alarm before 10 minutes but must alarm before 50 minutes. At 400 ppm alarm must not alarm prior to 4 minutes but must alarm before 15 minutes of exposure per Underwriters Labs UL 2034 standard. So heat is really not a factor as air/CO cools rapidly and mixes with the air in the RV. There is no requirement in any standard for the installation height of a CO alarm. So the propane detector portion of a Dual alarm is the gating factor on where to install the alarm.