Gas ranges and CO production

[Bain]

All I ever do with ovens is turn them on, make certain the convection fans are spinning if applicable, and check temperatures with a laser thermometer. But today there was a crudded-up oven with goop on the burners, so out of curiosity I whipped out the Monoxor II. The CO level raced to over 200 PPM and would have shot up higher if I hadn't turned the oven off. So now I'm wondering, did I actually observe a defective oven that wasn't properly combusting its gas, or do all ovens spit out CO this way? The EPA says we can endure no more than 8 PPM over an 8-hour period. So what's 200 PPM gonna do to someone standing over a stove? Being the obsessive compulsive idiot I am, I now will be checking the CO output of ovens in every house I wander into. Unless, that is, someone already knows about this stuff. The photo's out of focus, OBTW.

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[hausdok]

Hi,

Maybe the CO was produced by the burning crud on the burners!

Generally speaking, if a stove is adjusted properly and working OK it won't produce any CO. If it wasn't the smoke from the crud producing the CO, I'd have to believe that it was caused by crud that's blocking the burner orifice and causing the thing to burn crappy.

OT - OF!!!

M>

[Bain]

Exactly, Mike. That's what I thought. That's why I yanked out the CO detector just to see if the gas was incompletely combusting because of all the yuck. What I didn't know is what was SOP for ovens.

[randynavarro]

I don't use a CO detector anymore for gas appliances, but when I used to, the CO always spiked (sometimes up to 400-500ppm) upon the burners firing in the oven. I have no reference to state whether this was correct or not, but I gotta think that if every gas oven did this, then its probably normal.

[randynavarro]

Wait, I read your post again and am confused.

You show in the picture and describe high CO at the burners but then you switch to asking about CO levels in ovens.

In my experience ovens always show high CO upon startup but burners do not.

[Jim Katen]

Originally posted by Bain

. . . So now I'm wondering, did I actually observe a defective oven that wasn't properly combusting its gas, or do all ovens spit out CO this way?

Most gas ovens produce a good whiff of CO on startup. It's very common. Also any goop on the bottom of the oven will give off CO as it slowly combusts.

The EPA says we can endure no more than 8 PPM over an 8-hour period. So what's 200 PPM gonna do to someone standing over a stove?

Probably not much if it's for a short period of time.

Being the obsessive compulsive idiot I am, I now will be checking the CO output of ovens in every house I wander into. . .

While you're at it, measure the CO output of electric ovens. You'll be surprised at the results of the dirtier ones.

If you want to see some serious CO, measure the output of an electric oven during its cleaning cycle. Some of those things put out enough CO to kill pet birds.

- Jim Katen, Oregon

[Bain]

Randy,

The exhaust from the oven discharges from the vent behind the burners, hence the confusion regarding the photo. Jim, as always, you're two steps ahead of me on this one. I'll follow your advice and, hopefully, satisfy the little OCD demon inside of me . . .

John

[Brandon Chew]

Try thinking of it this way. It is the concentration (ppm) AND the duration of exposure that determines the health risk. So, you could be exposed to a high ppm of CO for a short period of time and be ok while a much lower ppm for a long enough time can kill you.

Most fuel burning appliances will kick out some high levels of CO during startup until they reach their normal operating temperature. With gas ovens or ranges CO is usually not cause for concern unless the flame is out of adjustment (yellow), and even then the oven needs to be in use for a prolonged period of time. Every now and then you'll read in the paper about someone getting CO poisoning from using their oven to heat their home. Makes you wonder if the post meal snooze after the Thanksgiving meal is due to eating the turkey or cooking it ...

Brandon

[kurt]

This is why I put my CO detector on the shelf several years ago. Taking odd sniffs w/portable testing equipment doesn't tell one anything.

[Neal Lewis]

I did measure the CO from my electric oven during the cleaning cycle a couple of years ago just to prove it wasn't an urban myth. The CO did get up to about 150 and the oven was kinda dirty. I don't have a bird, but the dog, cats, guineau pigs and fish survived the cleaning cycle...

[rlskfoster]

From what I understand, you can make any stove top gas burner throw off considerable CO by just throwing a pan over the flame. I haven't tested this myself. Anyone else heard this.

Buster

[Bain]

Kurt, I'm with you, and seldom even tug the CO detector out of my bag. Like I said, I was merely curious about what was spewing out of the oven vent.

Most gratifying of all, though, is to find out I'm not the only one who's wondered about this kind of thing and wanted to check it out. Neal and Jim have even measured the CO production of electrical ovens, which I'm sure I'll do myself at some point just because. I'm not saying it terribly well, but I sometimes think I'm a little nutty when I catch myself wondering about something like this. And I honestly know it's whacky since I've never heard of anyone succumbing to CO poisoning because they overcooked a lasagna. Having said that, and with utmost kindness and respect, it's nice to know I'm not the only one whose mind meanders around something a little off the wall like the CO production of an oven.

[Jerry Simon]

Originally posted by kurt

This is why I put my CO detector on the shelf several years ago. Taking odd sniffs w/portable testing equipment doesn't tell one anything.

You just don't like little dogs and cute ponies.

[hausdok]

I guess I've got a different mindset.

I grew up around a gas stove in a house without an exhaust fan in the kitchen. It had a constant pilot, not an electronic one, and assured that the windows were dripping with condensation in the winter. Nobody in my family suffered from migraines, unexplained cold or flue symptoms, pink pallor, confusion (not alcohol induced) or any other symptoms of CO poisoning....ever.

Gas stoves burn cleaner than cigarettes. I'm a non-smoker. I bet that growing up my father's then 2-3 pack a day habit, my mother's nearly 2-pack a day habit and my older sister's constant chain smoking produced a whole lot more CO than that stove every did.

ONE TEAM - ONE FIGHT!!!

Mike

[kurt]

Just so's you all know that I'm not a constant fit of grumpiness, I went through a deep experience w/CO testing over a period of almost 13 years.

For some reason I got it in my head that CO testing was the holy grail. My first gear was a Draeger tube system; digital readouts were still about 6 years away. I'd blow $20 worth of tubes on a single house; that's how important I thought it was. I ran more red herrings to ground than I can remember (or want to).

Then it went digital; I got even more nuts 'cuz I was so into the BRP protocol, and then the can thing that the other CO nut @ the time thought was the grail.

Then, I had the good fortune to have a customer who was a pretty competent scientist, & he gently explained all the interesting things about handheld portable testing equipment that I didn't know.

Then, I put the thing on a shelf & started telling folks to stick a CO detector in their house, and started paying more attention to the stuff I can actually know something about.

[Bain]

I always knew you had the heart of a young child, Kurt. You keep it in a glass jar on your desk, right? []

[kurt]

Right where I can keep my eye on it.....

[homnspector]

I have a small CO detector I wear on my belt turned on throughout the inspection. I don't pay much attention to it unless the beeper goes off, which has happened a few times. More for my own safety rather than "testing". One house I was in was 400ppm+. I quickly went through trying to find the source with no luck. Finally told the homeowner I was getting high readings. It turned out her husband warmed up the car with the garage door to the kitchen open! (another good argument for self closing doors). I told her that probably wasn't a real good idea.

I have never found an appliance (with the exception of a gas oven) that produced high levels of CO.

[Terence McCann]

The only time I use a CO detector is on a reallllllly old furnace. I put the probe in one of the registers after 15 minutes or so and see what the levels are like.

[Jim Katen]

Warning! War story ahead.

I was inspecting a restaurant that had a rooftop gas furnace. The peculiar thing was that they had built a second roof about four feet above the first and the furnace was venting into the resulting "attic" space. The walls of this space were almost entirely louvered, so I thought it might just be ok.

To get to the furnace, I had to climb my extension ladder and squeeze through an opening between the louvers that was about the size of a legal pad. Once inside, I had to crawl over a bunch of ductwork with sharp edges, and crawl around a giant swamp cooler. Then I found a spot just large enough for me to squat in front of the gas furnace.

Being a smart guy, I started my CO detector and placed it on a duct behind me as a safety precaution. Then I went to work on the furnace. Within a few minutes of starting it, the alarm on my CO detector started beeping. (I had it set for 35ppm.) I glanced at it and saw that there were 45ppm in the air around me. "Ok," I thought, "not unexpected. I'll just finish up quickly." But as I tried to screw the access panel back on, something was wrong; the screws just kept slipping out of my fingers. "Damn!" I thought, "This would be a lot easier if I didn't have this screaming headache. Saaayyy, wait a minute. Headache -- why do I have a headache? Any why are my lips numb? It feels like a shot of novocain."

At that point, I glanced at the detector again and saw that it was pegged at 2000ppm.

I had a brief vision of my dead body wedged next to the furnace being pecked at by pigeons and I wondered, briefly, whether or not the CO in my body would affect the pigeons' health. They I thought, "Get a grip, Jim, it's silly to be thinking about that. The pigeons would already be affected by breathing this air, they might even die before getting to peck at me."

Reassured on that point, I somehow managed to navigate my way back to the opening, get onto and down from the ladder without killing myself, and reach the safe air of the parking lot.

Feeling returned to my lips within an hour but the headache lasted for the rest of the day.

I did finish the inspection.

- Jim Katen, Oregon

[kurt]

That, my friend, is a very scary story.

[Bain]

Yes, it is. About the only time I pull out the CO detector by rote is in old houses. More often than not, the chimneys aren't lined, they've pretty much imploded, and the flue is partially or completely blocked. Naturally, all of the flue gases from the boiler or the furnace are billowing back into the basement. I watch the CO reading soar up, up, up, and shut the boiler down.

Jim, your thoughts about the pigeons are fascinating. I just started reading, "Don't know much about mythology," and the author starts out by explaining how we have a sort of atavistic, evolutionary need to understand the world around us and our own little place in that world. You, Jim, find yourself in a life-threatening situation, and your mind instantly begins calculating everything that may happen next, including the behavior of the pigeons along with the consequences of that behavior for you both. I've been surprised in attics by squirrels, birds and bats--and though inane, as the sweat trickles down my face--my imagination kicks in and I begin thinking something like, "Okay, so Mr. Bat has been trapped in this attic for weeks with no food or water, he's probably rabid, and here I am presenting myself as a threat in his territory. He's gonna fling himself at me and start clawing and biting and how do I fight back without falling off the ceiling joists, but then do I really care about falling through the ceiling when a rabid bat is chewing my face off . . . " And on it goes. 'Course, not once have I actually been confronted or attacked, but I'll still likely have those zany thoughts ricocheting through my brain next time it happens just because of the genetic imprint in my head.

[Brian G]

Damn Jim, I'm surprized you could function to get out at that level. Just imagine if hadn't had the warning...probably would have been pigeon food. [:-yuck]

I carry a low-level CO detector with me when I work, a constant monitor intended for home use. It's gone off in 3 different homes, including a reading of 50PPM in a little 900 sq. ft. house in Bama. The lady of the house said her 7 year old daughter "kept a cold all the time". I told her what it really was; she was pretty shaken. They didn't have a CO monitor, but even if they did and it was a run-of-the-mill $20/70PPM alarm model, they wouldn't have known squat and the poor kid would still be sick.

For those of you I haven't bored with this before, please specifically recommend low-level CO monitors to all of your clients buying a house with ANY gas appliances. If they have kids lean on it a little. You may save a life one day without even being there.

For those of you I have bored with this before; sorry. I held it as long as I could. [:-taped]

Brian G.

So Sue Me! [:-dog][]

[Mike Lamb]

If you put foil on the bottom of the oven to catch pizza drippings or whatever, make sure it doesn't cover the air holes.

I once, I mean, a friend once did this and the CO detector in my, I mean, my friend's son's room went beserk in about 10 minutes.

Since it was a new appliance, he had a guy come out no charge and check it out. The guy said, "You idiot. You can't cover the air holes with foil." Dumb friend.