Carbon Monoxide Levels

Old 07-03-02, 07:50 AM
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gas stove

I have a 1986 Caloric Heritage series double gas oven. Standing pilot in both the top and bottom ovens and of course 2 cook top pilots. Recently my CO detector has been reading a constant 9 ppm in the kitchen and when I move it to other locations (ie sleeping areas) the number remains constant. I also brought home an industrial 4 gas monitor to see if maybe my detector was bad. This detector is meant to monitor air for confined space entry. The industrial monitor is reading a slightly higher number. When the oven is on for several hours the number goes up to 15 ppm throughout the house. Also, if I put the detector in the oven while it is off the detector goes up to 60 ppm. I then placed the monitor towards the back vent and turned on the oven. During start up the number went above 175 ppm. I know that CO is a natural occurance during combustion but what is normal. My question is what is considered an acceptable CO release with just the pilots on, when the oven starts and then while it is running for a few hours. We have cleaned the pilot assembly and adjusted the pilot.
Old 07-03-02, 04:23 PM
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Are you on natural gas or propane?
Old 07-03-02, 08:00 PM
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My volunteer fire department is called to about 30 CO related incidents per year.

Our multi-gas detectors are calibrated to sound alarms at at 35 ppm as are our CO only units. For us, 35 ppm is the life danger level. We evacuate and vent with fans.

In the course of our investigations we have found that 6-8 ppm to be the norm in the typical kitchen, that's pilot light emissions only, but that's not where a CO detector should be.

Air borne contaminats from cooking foods clog the unit and it will not be able to provide accurate readings. It should be in a sleeping or living area.

CO detectors mimic the human body; they, with their 9v or 110v power sources, burn off the air and measure remaining CO. Food vapor contamination in kitchens will shorten the CO detector's lifespan and hurt accuracy.

Start-up CO measurements, when gas appliances are first turned on, are always high and depending on ventings and other factors it can take several minutes to level to true CO operating output, so I wouldn't worry about that 175 start up.

Recent information we've received tell us to tell residents that the expected lifetime of a CO detector is 5 years, the same as smoke detectors.
Old 07-03-02, 08:20 PM
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Hello susieqr63. Welcome to our Heating and Cooling forum and the Do-It-Yourself Web Site.

Carbon Monoxide is always present everywhere. Outdoors, in may common areas like parking lots and street corners, the levels are often much higher than very often found in homes.

Your questions are valid but may be rather difficult to explain in a text only format and not being there in person to visually see the appliance in operation. However, based only upon only the information provided, I'll make an attempt.

The acceptable level for a home is any amount below a constant 10 ppm. That amount may not be coming solely from the stove appliance, since some CO is always present in the air from other sources. But any amount below 10 is considered acceptable.

The internal oven reading, in my opinion and once again based upon a non visual look, 60 ppm's is too high. Which may mean the pilot flames is not burning as hot as it should.

The condition with the oven pilot flame may be simply a dusty pilot flame condition. The pilots flame could be adjusted incorrectly and or impinging [touching} on something incorrectly or on something it isn't suppose to be in contact with.

In the above case, only a trained eye for probable causes may be able to see the problem and correct it.

It's perfectly normal, when an appliance is first turned on or fires up, to have elevated levels of CO. Accurate testing can ONLY be done after warm up. In the case of ovens, allowing 15 minutes warm up time may be needed.

Oven cleaniness is also a factor. Uncleaned ovens pollute more.
Ovens internal physical conditions are also factors.
Ovens emit more CO immediately after burner shut downs.
Atmospheric conditions outside a home also can effect the levels of CO.

Lots of factors to consider. Using the correct CO testing methods and taking an average reading determines the correct results.

It's also possible there is another gas appliance emitting CO in the house. That appliance may be contributing in part, a part of that constant level reading you obtained.

In regards to what is normal, there isn't much, except remaining below 10ppm's when no appliance is on. An exceptable ambient level, when the oven is on is 50ppms.

An oven should read less then 100ppms after warm up and during normal operation. This figure is not always obtainable. Below 200ppms is closer to acceptable and more realistic.

Ovens are not a common appliance to cause enough Carbon Monoxides to cause ill health or death. Furnaces are the number one problem source. The second most common is water heaters.

This determination is based on what is commonly referred to as "appliances that are automatically operated." Automatically operated means without the users input after initailly turning the appliance on.

This is yet further determined by an appliance being either automaticlly operated and or remotely operated. A furnace can be considered both automatic and remotely operated, if the unit is not plainly visable. A water heater is simply automatic because it is able to be set and is most often not plainly visable.

To the best of my knowledge, I have never heard of a case where a person has died from carbon monoxides produced by an oven. A person may become sick or ill from oven CO but most likely has never died from it's useage.

If you need further assistance, use the REPLY button to add any additional information or questions, etc. Using this method also moves the topic back up to the top of the list automatically.

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Last edited by Sharp Advice; 07-03-02 at 08:41 PM.
Old 07-04-02, 07:08 AM
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I just wanted to add or better clarify that when we (fire department) are called for a CO incident we check the whole house or apartment and record CO levels in each room and at each appliance; and it is from that investigation process I can tell you that pilot light only levels in a typical kitchen is normally under 10 ppm, which supports Tom Bartco's experiences.

We have found that furnaces are the #1 culprit in our FD experiences for genuine CO alarm activactions, (after bad, dead, or low batteries false alarms) and that problem (usually in the Fall months) is solved by cleaning and proper venting; but we also have found that other activities also cause CO detectors to go off - nail polish remover, oven cleaners, and charging automotive batteries will all activate a CO detector.

For residents that are very concerned about CO we leave 24 and 72 hour test cards behind. (These are usually available from the gas company too). The cards (ours are manufactured by MSA - Mine Safety Appliance company) have a small glass tube glued to them and inside is a white litmus paper. The end of the glass tube is snapped open and the card is placed in a non-kitchen area, usually in a bedroom or living room, or both, and checked 24 and 72 hours later. If the litmus turns brown there is a CO condition that needs professional attention.

Last edited by UpAllNight; 07-04-02 at 07:27 AM.
Old 07-09-02, 11:08 AM
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Thanks for all the replies. The culprit was the pilot in the top oven. It was burning too high and was hitting the plate which covered it. My husband cleaned out the pilot assembly and lowered the flame. No carbon monoxide detected in any room of the house now. I had the industrial MSA multigas meter reading continuously for several hours. As for the other gas appliances in my home (hot water heater, dryer and furnace), there was no co leakage from them. My husband is a HVAC technician so he knew where to check for leakage. Thanks again for the info.

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