Carbon Monoxide Alarm going off due to the head?

[Leeward Rail]

Recently I had a new carbon monoxide alarm, which is mounted on the bulkhead in the head, go off when sleeping aboard.

Everything seemed fine but I opened all the hatches just to be sure. Later the detector kept going off occasionally.
-No fuel burning devices where running.
-No alcohol fumes from the stove
-the batteries weren't charging to produced hydrogen.

I moved the alarm to the settee area and it was fine for a couple weeks.
A few days ago I put it back in the it's mount on the head bulkhead, and today it started going off again.

I found this list of possible gases that can trigger a carbon monoxide alarm...

Other gases that can set off carbon monoxide detector includes:

• Isopropyl alcohol
• Sulfur dioxide
• Acetylene
• Propane
• Hydrogen sulfide
• Dimethyl sulfide
• Mercaptan
• Ethyl alcohol
• Ethylene
• Methyl alcohol
• Hydrogen cyanide, and
• Nitrogen dioxide

Practical Boat, in one of their tests, states:

"Instead of oxidizing the waste completely, they go only part way, producing some extremely malodorous products in the process; organic acids, assorted mercaptans, and hydrogen sulfide gas are chief among these"

So mercaptan and hydrogen sulfide are on the list...

Have you heard of fumes from a holding tank, causing a carbon monoxide alarm to go off ?
The smell from the tank isn't really bad, although it is noticable. (to be resolved next spring with a likely switch to an MSD Potti)

 

[MikeHoncho]

It’s possible. Each sensor manufacturer has its own cross sensitivities for sensors. More likely than not the sensor itself is going south. The septic would have to be sitting there a while to get a build up of H2S.

 

[All U Get]

Whatever you are eating, I’m proud of you man. But as Mike said your sensor is telling you something is causing the alarm. A better sensor could eliminate some of the mystery. Location is important when mounting a sensor. For example a smoke detector next to a wood stove or toaster would probably not be the best option. If you can close the door to the head or mask it off with plastic and tape, that could give you a source for the gas. Different cleaning agents can also cause detectors to activate.

 

[Parsons]

Aside from giggling about what you ate for dinner .... what else do you put down your head? Are you using a head additive for odor control? I've found that @Peggie Hall HeadMistress 's suggestion of using Raritan KO and cleaning with CP is the best solution for odor control, if you are looking for alternatives.

 

[Leeward Rail]

The septic would have to be sitting there a while to get a build up of H2S.

That makes sense and may be the cause. The head hasn't been used since last year, because the boat spent the season on land while I worked on it.

It only has a 10 gal tank. I plan on pulling and cleaning the tank to check it's condition (made in 78), and installing new hoses. Or install a 5 gal MSD pottie to increase the number of flushes and reduce odor risk. I am leaning towards the latter.

A better sensor could eliminate some of the mystery

The ultimate solution would be a gas detector to determine what the carbon monoxide alarm is sensing.

I have a second alarm so I plan on swapping them to see if it is an issue with this new alarm.

Location is important when mounting a sensor. For example a smoke detector next to a wood stove or toaster would probably not be the best option. If you can close the door to the head or mask it off with plastic and tape, that could give you a source for the gas.

Thats exactly why the alarm is where it is. Near the v berth and far away from the alcohol stove, inboard engine etc.

The plastic partition idea is something I will try later this fall if I have time. Even just for curiosity sake.
Next year I hope to have no odors at all once the system is fully redone.

Whatever you are eating, I’m proud of you man.

Aside from giggling about what you ate for dinner ....

Unfortunately I can't take credit. The head was last used by the previous owner.

 

[JamesG161]

Mercaptan

That is Rotten Cabbage odor.

Put in Methane and Propane gas so people smell a leak.

Jim...

 

[Leeward Rail]

That is Rotten Cabbage odor.

Put in Methane and Propane gas so people smell a leak.

Jim...

Yup. Interesting that a carbon monoxide detector will detect it.
No propane aboard currently. Just used for the bbq.

 

[JamesG161]

What is the brand of your unit? Kidde?

 

[Leeward Rail]

What is the brand of your unit? Kidde?

Might be.. Will confirm tonight.

 

[Justin_NSA]

I tried a different brand detector and it still goes off. It's not even mounted in the head.
We don't do #2 in our head. Neither did the PO.

 

[Leeward Rail]

I tried a different brand detector and it still goes off. It's not even mounted in the head.

Hmm. Hopefully @Peggie Hall HeadMistress can lend some insight.

Do you have an alcohol stove or are the batteries possibly giving off hydrogen?

Very annoying when I plan on having our diesel espar heater working next spring.

 

[MikeHoncho]

You would have to have a aray of different meters and technologies to qualify the specific gas. All toxic sensors have cross sensitivities. Your better off ruling them (gases) out through a process of elimination. Sounds like the only source is the septic. It would have to be leaking or had leaked a lot or vented not to the outside. Id pump it and clean it to see if there is any changes. Freons/refrigerants will hit on various CO sensors also.

 

[Justin_NSA]

Hmm. Hopefully @Peggie Hall HeadMistress can lend some insight.

Do you have an alcohol stove or are the batteries possibly giving off hydrogen?

Very annoying when I plan on having our diesel espar heater working next spring.

The batteries are way aft in the laz. I'm not sure what sets the moniter off. My dock mates even let me know my boat was beeping through the night. Embarrassing, but hate to ignore it. That's how people die in their sleep. This began years ago and we don't use a monitor

 

[MikeHoncho]

If you don’t have a CO source there is no concern for CO. Turn it off. If you are running the engine, heater system or cooking then yes, have it on.

 

[Leeward Rail]

you don’t have a CO source there is no concern for CO. Turn it off.

That is likely our 2nd option, after we refit the head. Currently we have a smoke/CO combo that has a "10 year" battery. No easy way to turn it off, once you pull the tab that activates it. One with a switch would be a good option.

 

[Leeward Rail]

What is the brand of your unit? Kidde?

Based on photos yes.

Combo smoke/Co talking detector with 10 year battery.

Based on the reviews on the actual Kidde website, that model series are horrible, and prone to false alarms.

Combination Smoke and Carbon Monoxide Alarm, Sealed Battery P3010CU | Kidde

P3010CU is a combination smoke and carbon monoxide alarm with a ten-year sealed lithium battery with a voice warning system

www.kidde.com

 

[kappykaplan]

I purchased a marine-rated Xintex unit - no more false alarms.

 

[Leeward Rail]

I purchased a marine-rated

What makes them marine rated?

 

[kappykaplan]

Great question - hopefully their website can do a much better job of answering the question than I can. I used to have a residential unit on my boat - it was worthless because of all the false alarms.

The CMD6-M is the most advanced marine CO alarm on the market, featuring a state-of-the-art sensor that is unaffected by common cleaning solvents.

Marine Carbon Monoxide Detectors | Fireboy-Xintex

Fireboy's model CMD-4MR-RLY and Model CMD-4MR Marine Carbon Monoxide Detectors. Optional conversion plate for mounting CO Sentinel Carbon Monoxide Detectors

www.fireboy-xintex.com

 

[Justin_NSA]

What makes them marine rated?

It was expensive??