Carbon Monoxide

Question for the group, I've been having an issue on our boat with our carbon monoxide alarms going off. It's when we aren't running and haven't been for some time. What possibly could be generating CO? I open the windows, vent the boat when this happens but I need to figure out a root cause. Appreciate any ideas anyone may have.

Are you using a CO monitor designed for marine use? Home models often false alarm on a boat. Don’t know why but they do.

Nearby boats with gasoline engines running? I have been told that a battery / batteries that are over charging will set them off.

Home CO detectors are just fine in my opinion, but they do have a lifespan. Yours may be nearing the end of it's liferspan.

Another thing I have seen is that battery gasses from a hot cell or overcharging can cause a CO sensor to alert. Perhaps that is the issue?

After 12 years aboard with home detectors...

They will sound definitely for overcharging batteries....

And it seems like when the air is cool and damp they tend to sound off as well...not sure if that's because of low battery charge or not.

Huh. They are home detectors. Battery charger is on, could be overcharge I suppose.

If the dector is older replace it and also check your batteries, off gassing can cause an alarm.

Comodave said:

If the dector is older replace it and also check your batteries, off gassing can cause an alarm.

Click to expand...

I've replaced my entire bank of 3 8ds this summer, wonder if there is an issue with the charger.

psneeld said:

After 12 years aboard with home detectors...

They will sound definitely for overcharging batteries....

And it seems like when the air is cool and damp they tend to sound off as well...not sure if that's because of low battery charge or not.

Click to expand...

True. Mine used to go off the first weekend in the spring when the batteries were getting their initial charge from winter.

In addition to batteries gassing off, and this may not be your problem, but gas fired stoves, ovens or heaters will set of alarms if there is not enough air circulation. Same can occur with fresh paint, varnish, carpet or anything with VOC emissions. This was explained to me by an ABYC tech a few years ago who said they may be working on this for an upcoming supplement however I’ve not seen it yet. VOC’s can also gum up the circuitry I’m told

Rick

I had at least two of the main reasons mentioned happened to me last month.

1 a truck running nearby for a long period of time triggered them and it took me a while trying to figure it out.

2 batteries where getting overcharged through my inverter charger when i looked at the voltage was at 14.8 and i could actually smell foul.

took all detectors dunked them in a 5 gal bucket.

bottom line i will not get the combined detectors anymore.

ofer said:

I had at least two of the main reasons mentioned happened to me last month.

1 a truck running nearby for a long period of time triggered them and it took me a while trying to figure it out.

2 batteries where getting overcharged through my inverter charger when i looked at the voltage was at 14.8 and i could actually smell foul.

took all detectors dunked them in a 5 gal bucket.

bottom line i will not get the combined detectors anymore.

Click to expand...

1. The truck was emitting carbon dioxide. It was finding its way into your boat The detectors where doing their job.
2 Did you fix your over charging problem?

Don’t kill the messenger.

floatingmick said:

Question for the group, I've been having an issue on our boat with our carbon monoxide alarms going off. It's when we aren't running and haven't been for some time. What possibly could be generating CO? I open the windows, vent the boat when this happens but I need to figure out a root cause. Appreciate any ideas anyone may have.

Click to expand...

Most CO detectors have a shelf life (~5 years, IIRC), and sometimes sounding off is the warning to you that they need to be replaced.

And/or, sometimes sounding off is meant to signify a low battery condition.

Or there's the battery off-gassing thing folks have mentioned.

-Chris

+1 for batteries. The only time I had an alarm was when plugged in for a while at a marina and I assume batteries were getting highly charged and off-gassing. If it happens, try venting the cabin then unplugging and see if it happens again.

The way I understand it, marine carbon monoxide detectors are made differently than land-based (home) detectors. They use what they call a "Time Weighted Average" to avoid false alarms. They also cost 4 times what a land-based detector costs so you have to decide what's more important to you: saving $ or avoiding annoying false alarms.

Bob

Bobby Lex said:

The way I understand it, marine carbon monoxide detectors are made differently than land-based (home) detectors. They use what they call a "Time Weighted Average" to avoid false alarms. They also cost 4 times what a land-based detector costs so you have to decide what's more important to you: saving $ or avoiding annoying false alarms.

Bob

Click to expand...

Good land based detectors use TWA as well. The marine detectors usually have a wider operating temperature range and may last longer in a corrosive, salty environment though.

I have both a hard-wired marine unit and 2 battery operated home CO monitors aboard. All 3 will sound with excessive battery charging as well as if the holding tank is full of urine and starts to overflow!

I employ many types of direct reading instruments in my profession. CO sensors are available in three basic flavors: electrochemical, metal oxide, and colorimetric. Each have positive and negative characteristics. ALL direct reading instruments, by their very nature of ingesting the target atmosphere, suffer from degradation due to ambient temperature, humidity, and possibly the target compound.

You would think that the manufacturers are holding nuclear secrets when trying to get a simple and straight answer as to the sensor type provided. All I can get from the manufacturers of “marine” units is that their units “better resist the adverse effects of temperature and humidity.” Better than what? I don’t think it’s the sensor type. On my boat I use reasonable quality “home” CO detectors and swap them out every couple of years or at the first sign of erratic behavior.

For all types of CO detectors, any gas of similar molecular size and chemical reactivity can produce a false positive (alarm). Common CO detector interferents include acetylene, dimethyl sulfide, alcohols (ethyl, isopropyl, methyl), ethylene, hydrogen cyanide, hydrogen sulfide, mercaptan, propane, nitrogen dioxide, sulfur dioxide, and probably some others.

So there you are. Thanks for that excellent explanation.

Thanks everyone, i think it's a winter investment in better CO2 detectors.

Please pay attention to the batteries off-gassing. A friend took his family and his brother's family out for a week after not using their boat for nearly a year. After dropping anchor they noticed their batteries were low on water and filled them all up. That night the temps were low so all of the windows were closed and around midnight the carbon monoxide alarm went off. My friend's brother was super-annoyed and was going to disable the detector but his wife insisted he call 911. Feeling foolish he did what she demanded. The local fire chief came over on the police boat and when he stepped inside his vest-mounted CO detector went off like crazy. He evacuated them all to the open flybridge then opened the windows to (literally) clear the air. He informed them that if they had disabled the alarm they would all have been dead by the morning. Carbon monoxide is odorless and the first symptom of being poisoned is sleepiness. So you fall asleep and wake up dead. Check your battery charger and your new batteries!!!

Robster_in_edmonds said:

Please pay attention to the batteries off-gassing. A friend took his family and his brother's family out for a week after not using their boat for nearly a year. After dropping anchor they noticed their batteries were low on water and filled them all up. That night the temps were low so all of the windows were closed and around midnight the carbon monoxide alarm went off. My friend's brother was super-annoyed and was going to disable the detector but his wife insisted he call 911. Feeling foolish he did what she demanded. The local fire chief came over on the police boat and when he stepped inside his vest-mounted CO detector went off like crazy. He evacuated them all to the open flybridge then opened the windows to (literally) clear the air. He informed them that if they had disabled the alarm they would all have been dead by the morning. Carbon monoxide is odorless and the first symptom of being poisoned is sleepiness. So you fall asleep and wake up dead. Check your battery charger and your new batteries!!!

Click to expand...

Batteries don't actually produce CO. However, the battery gases in high enough concentration will set off a CO alarm.

Cigatoo said:

1. The truck was emitting carbon dioxide. It was finding its way into your boat The detectors where doing their job.
2 Did you fix your over charging problem?

Don’t kill the messenger.

Click to expand...

i haven't fix my overcharging issue yet. happens when pluged in through my inverter/charger unit. I am thinking to use the inverter function only for now.

Thanks

All good info. I don’t have a CO detector in the engine room and thinking this would be a good practice with a genny and engine. Am I thinking correctly?

jimdavi said:

All good info. I don’t have a CO detector in the engine room and thinking this would be a good practice with a genny and engine. Am I thinking correctly?

Click to expand...

Pretty sure they are for occupied spaces to protect humans....

Most recommendations I have seen are for sleeping areas or other places with less airflow and/or longer periods occupied.

from the net...

"Where should you place CO detectors?

Kitchen - You can install them in your kitchen – but the key here is to keep them away from the flame-producing appliances and direct sunlight. ...

Bedrooms - While the CPSC recommends at least one carbon monoxide detector on each level of a home and near sleeping areas, people often overlook that you can put one in the hallway outside of all bedrooms. ...

Basements ..."

If you have a friendly fire department, have them bring a portable detector down and check it out. As a former firefighter, false alarms with home CO detectors were 95% of the CO calls we got, the sensors fail frequently long before their expire date. I would expect your local FD would make a courtesy call at no charge and relieve your anxiety! The one I worked at certainly would.

Thanks all- just installed one in the engine room.