Indoor air quality and gas ranges?
Matt
| Posted in Energy, Heating & Insulation on
This came up in another thread, and my question is more from an “I’m curious” standpoint. I thought it was important enough though to start a separate thread.
With all this talk these days about indoor air quality, CO detectors, backdrafting, and the like it would seem that gas ranges can’t be anything more than a liability. Yet they are considered highly desirable and an upgrade. Granted most people have a range hood that is vented to the outside but who can say they turn on the hood every time the cooktop or oven is used…. I don’t get it. Can someone ‘splain’ it to me?
Replies
We do. Every time.
John
There is no logical explanation.
In my area, I'd say less than 1/2 of new construction vents the kitchen outdoors, and well less than 25% of all houses do.
several years ago, I got called out to a house with CO alarms going off.
The HVAC folks and plumbers and gas company folks who "investigated" were all skunked.
I wen out in the early evening. I was running my tests on the furnace and water heater, I was getting relatively low readings in the furnace and water heater flue gases, and yet my low level unit that I always carry was indicating growing CO in the basement.
Huh?
On impulse, I stuck my combustion analyzer probe in the duct work, and got a relatively high reading. (Generally, checking ductwork for high CO is the sign of an amateur CO "analyst" who is following the "Professional Equipment Catalogue Photographer 'Protocal' for CO Analysis")
Turned out that the oven had been turned on while I was investigating in the basement, and the stove was blowing enough CO that it pegged my meter when I stuck the probe in the vent from the oven.
Looking at old kitchen pics and illustrations, gas stoves "originally" were vented, but there is no residential requirement that I know of to do so.
Thanks Bob...
You said "In my area, I'd say less than 1/2 of new construction vents the kitchen outdoors, and well less than 25% of all houses do."
I see similar here, however gas ranges are more for the more expensive homes which do get externally vented kitchen hoods or maybe a microwave.
Anyway in your example situation, would say this was a dangerous situation? Was the oven in need of repair?
And when you said: "Turned out that the oven had been turned on while I was investigating in the basement, and the stove was blowing enough CO that it pegged my meter when I stuck the probe in the vent from the oven."
When you said "vent from the oven" - what is that? I didn't know gas ovens were vented. Maybe I'm a DA?
>> Anyway in your example situation, would say this was a dangerous situation? Was the oven in need of repair?
Yes - on follow up, the appliance repair guy could not get the CO levels below several hundred ppm and the stove was scrapped.
And when you said: "Turned out that the oven had been turned on while I was investigating in the basement, and the stove was blowing enough CO that it pegged my meter when I stuck the probe in the vent from the oven."
When you said "vent from the oven" - what is that? I didn't know gas ovens were vented. Maybe I'm a DA?
Sorry I was unclear - I believe all gas stoves have a vent from the oven - sometimes it's along the bottom of thre rear control panel, more often it is through a vent hidden below one of the burners
Generally stoves don't put
Generally stoves don't put out enough co to kill anyone if they are just used for cooking. CO may be bad, but the relatively low levels make additional requirments overkill.
Commercial stoves would kill someone if not for the exhaust vents since they are high btu and on a great deal more.
>>Generally stoves don't put
>>Generally stoves don't put out enough co to kill anyone if they are just used for cooking. CO may be bad, but the relatively low levels make additional requirments overkill.
First: Death is not the only terrible potential consequence of CO poisoning - "long term" exposure exposures to lower, non-lethal levels can cause debilitating life long damage.
Second: with such dangerous possibilities, "generally" really isn't a good basis for deciding on whether improvements are worthwhile.
Standard risk analysis involves 3 factors: (1) what is the likelihood of the risk (here, low, but not non-existent) (2) what are the consequences of the risk (here as high as death but including significant brain and body tissue damage) and (3) what is the cost of preventing the danger (here, adding a vent/flue, which we always do for a gas water heater.)
Having studied combustion and carbon monoxide and receiving several certifications in the field, my belief is that "we" are ignoring an important safety concern.
There is no right or wrong here, of course. But there can be differences in the degree of experience, knowledge and critical analysis brought to bear.
For more information on the potential health effects of CO poisoning, see coheadquarters.com
QUOTE
Today, Carbon Monoxide (CO) is the most commonly encountered and pervasive poison in our environment. It is responsible for more recent deaths (see historical death data for NYC) than any other single poison, and for enormous suffering and morbidity in those who survive.
Annually in the USA:
Tens of thousands of people seek medical attention or lose several days, weeks, months of normal activity from CO exposure
Over 40,000 emergency department visits for CO poisoning (estimated; Hampson, 1999)!
More than 450 people die through unintentional CO exposure (CDC)
As many a 2000 people die intentionally using CO (CDC)
It has been known for decades that CO poisoning can produce lasting health harm, mainly through its destructive effects on the central nervous system. Some studies found that 25-40% of people died during acute exposure, while 15-40% of the survivors suffered immediate or delayed neuropsychological deficit.
Now, an emerging body of evidence suggests that longer exposures to lower levels of CO, ie. chronic CO poisoning, are capable of producing a myriad of debilitating residual effects that may continue for days, weeks, months and even years. Keep watching this site for new information on this topic.
END QUOTE
>>Commercial stoves would kill someone if not for the exhaust vents since they are high btu and on a great deal more.
Make that "Commercial stoves could kill someone ...."
the ampount of co produced is not a function of BTU;
A relatively low btu flame with, say, a high degree of flame impingement, can produce huge amounts of CO, and a high btu flame produce very low amounts of CO.
The IRC currently requires mechanical ventilation for kitchens: 100 CFM intermittent, or 25 CFM continuous.
If older homes have been significantly sealed against air infiltration, they should also have a means of ventilating the range, especially if it's gas.
Most residential ranges are not used for more than an hour or so at a time. If the flame is burning a clean blue, there will be almost no CO produced. Oven burners are more difficult to see so as to know how cleanly they are burning, but stove tops are easy to see. Of course, this assumes that the user actually understands what he/she is seeing. Builders and manufacturers have to assume that the occupants are ignorant, uninformed and senseless, all of which can apply in some cases. It gets worse every year.
So, in answer to the OP question: yes, ventilation is required in new houses built to the IRC, and tightened older houses should likely have it too.
>> If the flame is burning a clean blue, there will be almost no CO produced.
A common belief, but an inaccurate one - I've tested many combustion appliances with a "clean blue flame" that were producing high levels of CO.
Up till now, I have never tested the CO levels produded by a blue flame, but your comment has prompted me to do it. I'll do some testing this weekend at home with range, WH and free-standing gas stove.
This raises some disturbing Q's about "ventless" heaters. I don't have one myself, but they are allowed by code, unless local jurisdictions prohibit them.
QUOTE
Up till now, I have never tested the CO levels produded by a blue flame, but your comment has prompted me to do it. I'll do some testing this weekend at home with range, WH and free-standing gas stove.
This raises some disturbing Q's about "ventless" heaters. I don't have one myself, but they are allowed by code, unless local jurisdictions prohibit them
END QUOTE
Not all blue flames also have CO, and not all yellow flames do. All orange flames have dirt in the combustion air, though.
What kind of tester will you be testing with? What protocol?
Be sure to test for the first minute or so after light off, after 3 minutes and after 5 minutes.
The CO levels will usually peak in the several seconds after light-off, then drop down to under 100ppm. The reading should then remain steady over the remainder of 5 minutes.
Steady at, say 110 ppm, is better than fluctuation from, say, 10 ppm to 50 ppm, because fluctuating levels will often climb to dangerous levels over time.
"Ventless heaters" have vents.... The whole house. As a BTer commented years ago, using one is like choosing to live in a chimney flue.
They are never to be used:
1: As a primary heat source (they are for supplemental heat only)
2. To heat a bedroom
3. To heat a bathroom
There should always be a window or door open, which kind of defeats the purpose.
Their "oxygen depletion sensors" protect against only one possible cause of excessive CO - buildup of CO2 from floor level which, if it reaches the flame, will deprive the flame of sufficient oxygen and thus cause CO to be produced.
"Oxygen depletion sensors" will not protect against CO caused by equipment malfunctions such as misaligned burners.
My tester is the Bacharach Monoxor II.
Thanks for the tips on testing.
And I am aware of the concerns you mentioned with regard to "ventless" heaters. I have never been happy with the codes' allowing them. I have always been suspicious that they got approved because nobody besides their manufacturers spent any money on testing them. We all know that tests can easily be designed or manipulated to produce the desired result.
If a house, new or old, is well sealed against air infiltration, where does makeup air come from when the range hood fan or bathroom vent fan is running?
If really well sealed, then a source of air is needed, with a heat recovery unit often being worthwhile.
Interesting idea. Do they have such things for bathroom fans? Certainly not retrofitted into older houses.
I don't see how you could use an HRU on a stove vent hood with all the grease in the out-bound air stream even with a filter in place.
There comes a point at which you have to just shrug your shoulders and say "You gotta die of something." I'm am certain that more people than are quoted above die and are harmed each year by stress caused by worrying about what is going to kill them.
But just maybe you have stumbled on the real reason people get so sleepy on Thanksgiving instead of the Turkey it might just be the oven being on none stop for 6 hours.
>>But just maybe you have stumbled on the real reason people get so sleepy on Thanksgiving instead of the Turkey it might just be the oven being on none stop for 6 hours.
That idea has been put forward for years by Jim Davis, the leading guru (and odd ball) of CO and combustion analysis
>>here comes a point at which you have to just shrug your shoulders and say "You gotta die of something." I'm am certain that more people than are quoted above die and are harmed each year by stress caused by worrying about what is going to kill them.
Risk analysis and assessment is necessarily subjective.
When I was young, those who promoted seat belt use in cars were also derided as excessive worriers.
And drunk driving was sort of shrugged off as not really an issue.
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When they came out with the new water heater flashback preventer specs several years ago, the requirement jacked up the cost of water heaters about $100 bucks.
I questioned whether it was really a "cost effective" requirement, society wide.
Then a fellow in my area (Toledo) was killed by an explosion when he was filling his lawn mower tank in the garage where his water heater was.
I still don't know if the requirement was "cost effective" but my view of the balance has shifted.
This would be interesting to post on CT to find out how many prefer gas to electric. Women, generally, decide about the type of stove and they are focused on how easy it is to use.
The big advantage of a gas range to the cook is exact and instantaneous control of the heat under a pan.
Most bread bakers, on the other hand, prefer an electric oven because the heat is more uniform, things brown better, and they can put a pan of water on the bottom to make a steamy environment that makes the crust expand better and get nice and crackly. Gas ovens, since they must constantly vent the combustion gases, remove water vapor as well, so bread crust does not turn out as well.
I got a gas range & oven, and one thing I learned real quick...NEVER COOK MENUDO INDOORS.
It makes CO2 as benign as Chanel #5...
"NEVER COOK MENUDO INDOORS.
It makes CO2 as benign as Chanel #5..."
LOL
Must be powerful stuff!
No question that the best free standing stove is a dual fuel. Gas top and electric oven.