Carbon Monoxide?

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Lenp
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Carbon Monoxide?

Post by Lenp » Mon Jul 25, 2011 2:46 pm

Yes, this is off-subject but looking at the postings, there appears to few other subjects!

Points to consider...
We all know that CO (Carbon Monoxide), which is a product of incomplete combustion, can kill.
To prevent CO poisoning, gas appliances, like hot water heaters, must be properly vented. But, we also know that most gas kitchen ranges and ovens are not vented.

Now...
A little searching shows that the typical hot water heater is rated at somewhere near 70,000 BTU and is always vented.
More searching shows a typical gas range is rated at sometimes as high as 76,000 BTU and are not vented.

The question..
I have read on line (tongue-in-cheek) that a a hot water heater, properly designed and operating, produces no hazardous CO.
If so, what is the difference in design, combustion, venting, aging that causes the efficiency of the hot water heater to drop down so that it can produce dangerous amounts of CO.

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Len
Len

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jimmy101
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Re: Carbon Monoxide?

Post by jimmy101 » Mon Jul 25, 2011 3:23 pm

1. I would think that air supply is one big difference. A gas range has an exposed flame with lots of access to air (adequate air is needed to reduce CO2 production). A hot water heater places the flame inside an enclosure which increases the chances of an inadequate air supply.

2. Visibility probably also makes a difference. The flame on a range is visible to anyone in the room. The flame on a water heater is generally not visible without getting on the floor and removing a cover or two.

3. Heat rating: A gas range may well be rated at a higher BTU output than a hot water heater but the range's rating is for all burners plus the oven(s) going at full blast, which doesn't happen often. The hot water heater only has two power settings; off and full blast.

Dean Huster
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Re: Carbon Monoxide?

Post by Dean Huster » Mon Jul 25, 2011 8:17 pm

I don't understand why you need to heat hot water. Around the area where I live, we only have to heat water if it's cold.

When you look at the burner output of a water heater vs. a gas range, you'll notice that the water heater's flame is much higher and a lot more aggressive. I'd assume that there is a good chance that oxygen can't get to the combustion area fast enough in many cases and CO is produced. The gas range has a lot more open air exchange and a much smaller flame size -- i.e., much less gas is shoved through the orifice, and a minimal amount of CO is generated.

Thanksgiving Day around here is the day most likely to see all four burners and the oven being used. Our daughter is getting one of the new gas ranges for her house,the the big oven will be cooking the turkey, the small oven the bread and/or pies, and the range top will have five available burners: corn, beans, gravy, potatoes and money -- if she can afford that stove, she has money to burn.
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

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dyarker
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Re: Carbon Monoxide?

Post by dyarker » Mon Jul 25, 2011 10:21 pm

4. The water heater runs automatically based on tank temperature, including at night while most people sleep.

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jwax
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Re: Carbon Monoxide?

Post by jwax » Tue Jul 26, 2011 7:08 am

This from the New York State Dept. of Health-
Malfunctioning or misused fuel-burning appliances are common sources of CO poisoning in the home. These include a malfunctioning furnace or water heater, non-electric kitchen range used for heat, portable non-electric space heater, or a gas or briquette grill used indoors or in a semi-enclosed space such as a porch. However, any appliance or heat source that produces CO and is not properly vented can cause a build-up of CO in the home. Schedule annual maintenance for furnaces and other heat sources to ensure they are properly vented and in good working order. Never operate a gas or briquette grill indoors or use a non-electric kitchen range for warmth.

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dacflyer
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Re: Carbon Monoxide?

Post by dacflyer » Tue Jul 26, 2011 11:19 am

with my experience with gas appliances..
if you have a nice blue flame, then the chance of co2 is minimal if any at all.
but if flame is white or yellow or otherwise, its not burning properly or clean.
i lived in a camper for a few years in my younger days, and used only the stove top as my only heat source. had a few bricks to collect heat as well from the flame, once room was warm, i turned down the flame, i had co2 detector, but it never went above "0"
in a gas water heater, the flame is not completely blue, you will see mixed colors. etc,, plus if it did not have a vent, i am sure the heat alone would cook you out of the house..
now the heat on demand heaters, i have seen some models that are vent free, but mount outside the house as well.. again, high heat release from flame..i have seen some gas cloth dryers, have a nice blue flame, some not. so its good they are vented outside house..

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haklesup
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Re: Carbon Monoxide?

Post by haklesup » Tue Jul 26, 2011 1:04 pm

I think most of the right answers were touched on.

1. A properly installed and functioning NG water heater wouldn't produce much CO but building codes are written to make the worse case safe. So if your WH were to malfinction such that it produced incomplete combustion, then there would be a concern

2. A WH runs much more often than a range and at unpredictable times. A range is usuallu operated for a short time in a large area that is often also ventilated by a range hood.

3. Incomplete combustion in a range is readily noticable and usually fixed promptly because it won't heat the food well and looks abnormal

Propapane is a different story, it always produces CO when it burns. If you're rural and run propane instead of NG, the need for a CO detector is much more important. Interestingly, my GF in Singapore has a Propane range in the kitchen. However, her apartment has several windows with no glass at all. It' so warm there, windows are never closed in the shared living areas. (AC is in the bedrooms but she never uses it)

Analogously, Chlorimated water will kill fish in much the same way CO kills air breathers. It binds to the hemoglobin more tightly than oxygen and the fish just suffocates.

gerty
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Re: Carbon Monoxide?

Post by gerty » Wed Jul 27, 2011 8:26 am

Last fall I tried to light the pilot flame in my gas heater in my shop. Everytime time I let go of the button on the valve, after lighting the pilot, it went out. Finally called the gas company, they cleaned the birds nest outta the flue.
It was all that was wrong, gas man said it was a common problem. Without the proper draft the pilot won't stay lit, and that in turn shuts the main gas valve off.

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haklesup
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Re: Carbon Monoxide?

Post by haklesup » Wed Jul 27, 2011 3:45 pm

usually when that happens to me or my friends, it's the thermocouple, pilot lights with finger on the button but since the theromcouple can't sense the flame, it prevents the main valve from opening. Birds nest makes sense but I would expect a minute or so of pilot burn with finger off the button before the combustion gasses suffocate the flame, I would also expect it to blow out with the finger on the button as well.

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Re: Carbon Monoxide?

Post by gerty » Thu Jul 28, 2011 5:17 am

The pilot wouild go out as soon as I took my finger off the button. I too thought it was the thermocouple and replaced it to no avail...

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