Confused about Co & LP Detectors

Perhaps I should have said "Combo Propane/CO detectors I would TRUST are non-existant.

Put a combo unit near the floor and if you have a CO issue you might just wake up dead.

Put a combo unit near the ceiling and you just might wake up 2 counties over (part of another joke I told once).

(Instructor to a pump jockey class: What happens if you have the right mix of propane and air and there is a spark: My Answer: you land two counties over
His Response: Exactly!)

Combo Propane/CO detectors are non-existant.

Actually.........

LP/CO Detectors are available
Atwood and Safe-T-Alert both have combo units.

And that is where the confusion comes from.......Different issues with where they should be properly mounted yet combo units are sold.

Combo Natural Gas/CO detectors are common, Combo Propane/CO detectors are non-existant. here is why

Natural gas is "lighter than air" CO, likewise is LIghter than air,, Thus both of those detectors are mounted on or near ceiling height.

Propane, on the other hand is heavier than air, and thus the propane (explosive gas) detector goes near the floor.

And before anyone comments: Lighter than air and heavier than air really should be typed Less dense and more dense than air.

But it may be easier to understand the way I typed it.

Since one goes high and one goes low, you can not combine them.

Kidde makes a nice CO detector with a ten year lithium ion battery for about $50,available at big box stores. No more changing batteries every year.


Oh and it has a readout so if the alarm goes off you can see how high the concentration is.

Well I guess that is where my confusion comes in. I knew LP would be low but just didn't understand the combo unit. thanks so much, I will buy them seperate then.

Dutch_12078 wrote:
I avoid the combination units, since LP detectors are normally mounted near the floor level, and CO detectors at eye level or above. For LP detection, I prefer the 12-volt wired units, but I prefer CO detectors that use 9-volt or multiple AA batteries for the flexibility in mounting them. Battery longevity is usually about the same as most smoke detectors. Both types will signal a low battery condition.

Exactly.....

Never understood the LP/CO combo.

Yeah, I agree with Dutch. LP is heavier than air so it sinks and pools at the lowest point if there's a leak. CO is slightly lighter than air and will tend to rise, but can float suspended in air, so the CO detector needs to be about head-level to pick up on the presence of the deadly gas.

I avoid the combination units, since LP detectors are normally mounted near the floor level, and CO detectors at eye level or above. For LP detection, I prefer the 12-volt wired units, but I prefer CO detectors that use 9-volt or multiple AA batteries for the flexibility in mounting them. Battery longevity is usually about the same as most smoke detectors. Both types will signal a low battery condition.

Birdie.....This is probably what you're looking for. It is LP and CO combined and is 12 volt only. Typically, if your batteries run low, the alarm will sound on the unit telling you your coach batteries are low.

LP & CO