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Back in the day I used to cook food in a small, badly ventilated room with a natural gas stove, turning it on for a relatively small intervals during the day, let's say 1-3 hours per day in total.

Someone told me that it could have caused carbon monooxide poisoning. Quick googling reveals that most modern burners would typically produce 0 to 50ppm with a tendency to a lower bound in that range. How reliable is this data assuming that burner consumes a "regular" natural gas commonly used in the US? Is there actually a concern in using natural gas burners e.g. in a small room?

Is there such a concern for gas furnaces most commonly used in the US in residential HVAC installations, assuming something breaks in the furnace's closed heating loop?

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    There is always a concern when using fossil fuel(wood, coal,oil, or gas) for heating/cooking. Most places heavy regulate the use of fuel burning devices, as to the ventilation, maintenance, and use of the devices, and the up keep of CO detectors. Most places even have regulations for them when using outside of the home.
    – crip659
    Jan 7, 2023 at 3:45
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    Or wood, for that matter. The question isn't the "typical" case -- it's the one that people don't expect. Note that this is why there are always warnings not to try using a stove as a heat source if your furnace goes out; even low levels of CO can be dangerous over an extended time. And, yes, CO detectors are mandated for good reasons; they may be the only warning you get.
    – keshlam
    Jan 7, 2023 at 3:52
  • I had CO poisoning once while working in a huge warehouse for eight hours or so, and using a Salamander to keep warm. It was no joke. Only once or twice in my life have I ever felt so sick.
    – gnicko
    Jan 7, 2023 at 4:01
  • Usually with gas you want to see just a blue flame, any yellow in the flame means CO can be emitted/build up.
    – crip659
    Jan 7, 2023 at 4:28
  • That's what I was thinking. As far as I understand as long as enough oxigen is provided to a natural gas burner, it wouldn't produce a lot of CO. I am not a chemist, still if I understand correctly natural gas is a lot more efficient in terms of burning, so normally burn reaction would yield CO2
    – J. A.
    Jan 7, 2023 at 5:17

4 Answers 4

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CO can be produced by a kitchen stove. You can look up research showing mild CO poisoning from tiny camping stoves in tents.

You don't hear so much about people dying from CO poisoning from kitchen stoves as you do from furnaces because of a few factors, mainly that a kitchen is usually large enough and has enough air circulating to feed the stove and ovens, and those appliances don't suffer the same air-flow problems as some furnaces.

Furnaces are designed to burn in a small combustion chamber with the heat being transferred to a heat exchanger, not to the immediate environment of the furnace. As a result there's a need to carefully manage combustion air to and from the burner. It's relatively easy for this to go wrong. A furnace can be placed in a room that is too small, or the air entering or exiting the combustion chamber can be partially obstructed. Furnaces run continuously for months with no attention from humans. Situations that starve them of air can develop and go unnoticed.

Range cook tops are in the open air. Maybe if you put a range in a small closet such as those used for furnaces you could choke the top burners but in a kitchen you'd have to be very deliberate to create a situation where open air burners are choked.

The oven has the largest burner and it also has air flow arranged by vents into and out of the combustion chamber. But unlike a furnace, 1) The flame is not enclosed in an isolated chamber, it's still in the room. If the vents are partly obstructed it can still ingest air from the environment, 2) Unlike a furnace there just aren't as many ways that people unintentionally block these vents or that they get naturally blocked by dust etc, and 3) People rarely go to sleep in the same room as a cooking appliance left on.

Cooking appliances can produce CO, it's just less likely for the circumstances to occur and more likely to be noticed quickly.

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Ranges and ovens emit a tiny amount of exhaust

I doubt you cook 3 hours a day unless you are making Thanksgiving dinner every day.

Normally the amount of gas and heat used in cooking is trivial, because the mass of food is tiny. 1 BTU raises 1 pound of water 1 degree F. (For reference, a 1500W microwave is 55-75 BTUs per minute). Other materials have lower thermal inertia than water, so 1 BTU raises a pound of them more than 1 degree F. So a 1-person meal probably doesn't even take 1000 BTUs.

It's not like the 250 pounds of water in a 30 gallon water heater (20,000 BTUs for an 80F rise).

Furnaces are another matter entirely, where you're making 50,000 to 100,000 BTUs per hour. Now you'd be making a huge volume of CO2, and the house's normal leakage couldn't be counted on to keep up. So they absolutely need vents.

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    Which isn't to say other combustion byproducts aren't an issue when cooking.
    – Huesmann
    Jan 7, 2023 at 13:12
  • My range can burn 89kBTU/hr with all elements switched on, and that happens almost daily, not just on Thanksgiving. And it's a fairly ordinary 30-inch free standing one, not a commercial-style beast. At that rate, poor combustion would produce a CO problem in minutes.
    – jay613
    Jan 7, 2023 at 13:39
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    @jay613 how often do you run it for a solid hour with all elements at hard max? 89k BTU/hr is not the same thing as 89k BTU. Jan 7, 2023 at 19:23
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    True @Harper-ReinstateMonica and also I think the stove top is unlikely to cause problems. The oven is mostly. A large one is 20kBTU/hr. If burning poorly, it COULD cause problems.
    – jay613
    Jan 7, 2023 at 19:41
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Join the Fan Club

Every natural gas appliance produces exhaust. Most of the time, most of the exhaust is regular air + carbon dioxide (CO2) + water vapor . But there can be carbon monoxide (CO), and even a little bit can cause problems if it starts to collect inside the house.

Because of all of that (you don't want lots of extra CO2 or water vapor, though they don't have the same dangers as CO), every natural gas appliance is vented to the outdoors. For a furnace or water heater, that is typically a vent that is attached to the appliance. For a cooktop that wouldn't work very well, so the normal solution is a fan above the cooktop. A nice side effect is that the fan will help remove cooking smells. But even if you are just boiling water, turn on the exhaust fan. A cooktop exhaust fan won't take care of all CO2 and CO, but it will help significantly, both removing the problem gases and drawing in fresh air.

Carbon Monoxide Detectors

We are all familiar with smoke detectors. Everyone should have them because there are many different sources of fire (smoking, electrical, combustion appliances, etc.) But anyone with any combustion appliances (natural gas, propane or fuel oil) should have carbon monoxide detectors.

Ideal is to have one near (but not too close, to avoid nuisance alarms) each combustion appliance, as well as at least one in or near the bedrooms. Even though the detectors near the appliances should react first (e.g., if your furnace has a problem in the middle of the night), at least one in the bedroom area is critical because the biggest risk is when people are asleep. But even when awake, the symptoms of CO poisoning are subtle enough (you won't smell anything like you might with a fire, and you won't smell mercaptan (the "natural gas smell") because it isn't a gas leak, it is incomplete combustion) that detectors can be truly life-saving.

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Clear regulation and preventive measures are used with fossil fuel(wood, coal, oil, or gas) for heating/cooking.

For protection heavy regulations exisit for the use of fuel burning devices, as to the unobstructed ventilation, maintenance, and use of the protective devices the CO detectors.

CO forms when there is insufficient supply of air leading to incomplete burn process.

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  • FYI, wood is not a fossil fuel. (But it can produce CO when burning.) Jan 8, 2023 at 0:47
  • That's true, I'm not arguing that regulations are useless. Yet practical measures show that with enough air supply the natural gas burner produces a very small amount of CO which is not detectable by CO detector. Like I said above, I'm not a chemist, yet from what I understand burning natural gas produces CO2 unless oxygen (practically speaking fresh air) is in really short supply.
    – J. A.
    Jan 25, 2023 at 4:22
  • Also I don't want to say above that I don't respect CO regulations. If someone is reading my opinions on this subject - keep in mind that CO poisoning is lethal and going above and beyond CO safety-wise makes total sense!
    – J. A.
    Jan 25, 2023 at 4:25

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