How much carbon monoxide is normal

[Slowpoke Slim]

All of the CO alarms that I had service calls on were related to fresh air vents being blocked during cold snaps.

The furnace rooms in the condos had a fresh air vents. Drove 4 hours round trip during a snow storm in the middle of the night to remove a diaper from a fresh air vent on one occasion.

The condo complex passed that bill on to the renters.

What most people don't realize is a CO detector needs to be mounted just under the height of your mattress. Carbon monoxide is denser then air and accumulates down low.

I cringe when I'm in the big box stores this time of year and they are selling combo smoke detector/ carbon monoxide detectors.

The carbon monoxide detectors in those units are worthless. You would be dead by the time it goes off.

That was the "old school" way of thinking. Detectors have changed. Look at the Parts Per Million (PPM) that they are now built to detect vs. the old styles we used to have. They go off now *much* earlier than will even give you a headache. Plus there have been intensive test done that show that any room will have enough CO mixed at all height levels to set off the detector from wall or ceiling height. CO is "heavier than air", but only just barely so. It doesn't settle that densely as we used to think 30 years ago.

This is just one of many detectors that we use, pulled the info sheet just to give you a reference:

https://www.systemsensor.com/en-us/Documents/CO1224T_TR_Manual_I56-3111.pdf

Look at pages 2 and 3. It takes 200 PPM to give you a mild headache after 2-3 hours of exposure. This thing goes off at 70 PPM after 2 hours.

These things have been thoroughly researched, engineered and improved. Again, CO is not anything that anyone in the business screws around with. Telling folks they are "worthless" is irresponsible. They are different now.

 

[otlski]

Our HVAC system is generically called a hydro-air system, at least it was 25 years ago. Hydro air has the safety advantage of never having the heated air come into contact with the exhaust air in the event of a heat exchanger crack. How it works it like this. The oil fired boiler heats up a water-filled heat exchanger and the water is circulated via pump to each of two zones. There is a second local heat exchanger on each floor. That second heat exchanger is hot water to air. In this way a failure at the boiler cannot mix CO2 into the air flow because the two are never near each other.

It may seem less efficient because it has two heat exchangers. It is not as bad as it might seem because the furnace is in the basement and the heat is sent to the second floor via copper pipe with little losses on its way. The same secondary heat exchangers are the combined air handlers for the air conditioning system.

We have been happy with it. Your mileage may vary.

 

[ultrarunner]

California had a tragedy with a blocked wall furnace vent and several died... if I recall the problem was during a cold snapped and furnace turned on...

Had not been used for some time and vent obstructed by animal nest...

More recent are generators and indoor charcoal BBQ

 

[ponytug]

We had a furnace die in an older home. Yes, you could smell the combustion vapors. Basically, a chunk rusted and fell out of the heat exchanger. My impression is that wall furnaces are not exactly gold plated and over engineered, but for the price, work well for awhile.

California does require carbon monoxide detectors. Typically, a construction permit will trigger an inspection for them, but homeowners can go a long time between permits. We have had three permits in four years and the inspectors have all checked for carbon monoxide detectors.

It does seem like every storm related outage and every winter there are people dying from indoor BBQs and indoor generators around here.

The modern detectors are not that expensive and last for a decade(ish), so the cost per year isn't much as a candy bar a month. I view it as cheap insurance against something that is hard to notice in time otherwise.

We have them in all the sleeping areas, and outside the kitchen.

All the best,

Peter

 

[ultrarunner]

Residential Rental triggers detector inspection as well as looking for double key deadbolt door locks, hot water too hot and not working grounds on grounded outlets.

Smoke and CO detectors generate a lot of fire dept and property management time... almost always a battery issue but by law they are now 10 year battery and then require replacement.

I keep extras in my vehicle and when car broken into several weeks ago lost several hundred dollars of new detectors.

 

[Slowpoke Slim]

The sensor portion of the detector is the piece with the service life. The sensor degrades over time, to the point where they will no longer detect the appropriate levels of CO. They used to have a 3 year service life, but as improvements to design happened over the years, it is not uncommon to see CO detectors with a 10 year SENSOR life. The one in the sheet I posted a link to happens to be a 10 year sensor. It really has nothing to do with the "battery", per se. When they reach End of Service, they are supposed to error out, or in some way report to you that they are out of service. There is also a mandatory Replace By date put on all new CO detectors sold.

 

[old and tired]

So I got my two new detectors... I thought of placing them low to the ground (since CO2 is heavier than air) Well, CO is actually LIGHTER than air and the detectors need to be on the ceiling!! My mind was blown... Just wanted to put it out there. Learned something new.

 

[Egon]

I goofed. CO has density just slightly lighter than air. I’d made an assumption based on its accumulation in garage pits of old.

For interest a news article:
'Lucky to be alive': carbon monoxide close call prompts warning from family | CTV News

 

[goeduck]

mine are 10 year ones with a test button.

 

[ultrarunner]

I bought for all the rentals the plug in ones originally... which means about 20" above the floor.

Since I have transitioned to the combo smoke and CO for the common hallways... more expensive but 10 year battery should make my life easier.

Sealed battery means no one can take out the battery... if the detector is missing then the tenant has a problem.