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#497241 --- 12/15/06 04:34 AM Natural Gas Stoves
BEerwoman Offline
Senior Member

Registered: 04/30/02
Posts: 2778
Am thinking of putting in a Natural Gas stove in my new family room. I have 2 options-vented or vent free. Does anyone have any knowledge of these or ever used them that could tell me the pros and cons of each? Thanks!!

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#497242 --- 12/15/06 04:41 AM Re: Natural Gas Stoves
Ranger Offline
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Registered: 10/23/00
Posts: 25141
Loc: GOD's 1/2 acre
I can't really tell you if one is any better than another, but, all the ones we build into our houses are all vented.
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#497243 --- 12/15/06 05:30 AM Re: Natural Gas Stoves
Dakota Offline
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Registered: 07/25/05
Posts: 989
Loc: Who? Me?
Unvented will add moisture to the air in the room. This can be good or bad depending on your humidity level.
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#497244 --- 12/15/06 05:52 AM Re: Natural Gas Stoves
BEerwoman Offline
Senior Member

Registered: 04/30/02
Posts: 2778
I meant to say firplace not stove if that makes a difference. Thanks for your input already!

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#497245 --- 12/15/06 06:25 AM Re: Natural Gas Stoves
bluezone Offline
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Registered: 12/19/04
Posts: 32556
Loc: USA
vented is far safer.
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#497246 --- 12/15/06 12:52 PM Re: Natural Gas Stoves
Jelloshot Offline
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Registered: 11/22/02
Posts: 11043
Loc: Right behind you.
"Safety" is rarely an issue, with todays standards, the vented and unvented are equal as far as safety, the biggest issue is what Dakota stated, humidity--the non vented ones will add humidty to your home, and it also depends on how much your going to use it. If its just for occasional use and ambiance a nice remote contolled one rocks! and you dont have to put more holes in the walls, for the UV and most are 98% or more heat efficient. Ours warmed up a large room so quickly we'd actually open windows..we also put little door fans to share the heat with the rest of the rooms close by..

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#497247 --- 12/16/06 12:35 AM Re: Natural Gas Stoves
VM Smith Offline
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Registered: 11/28/05
Posts: 38160
Loc: Ship of Fools
"all the ones we build into our houses are all vented."

You have a smart boss. This is a little long, but anyone thinking of getting a gas fireplace should read it. Personally, I'd go with a direct vent, which is efficient because it uses outside combustion air, rather than heated inside air, and because combustion products are vented outside through a wall, so you don't need a chimney.


A Challenge to Unvented Gas Heater Manufacturers (Updated from 2002)
Dec 01 '06 (Updated Dec 04 '06)

The Bottom Line ... The Vent-Free Gas Products Alliance were invited to respond to this review, in 2002 with technically responsible and verifiable counter arguments and they have consistently refused comment.

This review needed to be updated, in light of hundreds, if not thousands, of reports of soot damaged homes and the documented accidental death of a 14 year old girl and her dog, that was directly linked to a malfunctioning, unvented gas fireplace, fully equipped with a functioning oxygen depletion safety pilot. (ODS) People still haven't got the message. That young girl's death was 100% preventable.

Choosing a Space Heater? Do not consider an unvented gas heater if you care about your health and the health of your family members. After over twenty five years in this business, I know the technical issues involved and I know only too well, how an innocent mistake in judgment can quickly result in a disaster.

Vent-free gas space heaters represent one of the greatest, avoidable health and safety hazards, within the United States of America, for an estimated eight to ten million families.

When this debate began, many years ago, I seriously doubted there would be many consumers and engineer's who couldn't see the obvious dangers in using unvented gas appliances, in homes. Apparently, I was wrong, as sales of these products in the United States have actually exceeded the sales of vented gas space heaters, in recent years.

In 1996, The American Gas Association Research Division (AGAR) conducted a study on unvented gas appliances. Their summary, finally presented in full, in 1997, concluded that under very specific installation conditions, within specific regions of the country, providing proper and again case specific, Btu sizing and air ventilation for the room, these products did not represent a health hazard. However, their tests did not include all of the types and sizes of products currently promoted by the Vent-Free Gas Products Alliance (VFGPA). Their test methods were questionable at best (limiting the tests to very small gas units under 20,000 Btu's per hour) and their conclusions have been skewed and misrepresented through the selective exclusion of information published in the AGAR report, in order to suit the purposes of the current 24 Vent-Free Gas Product Alliance manufacturing members.

The 1996 AGAR study is the only single independent study conducted to date and the VFGPA refer to it as though it were the holy grail. The 1996 AGAR study was in fact funded, in part, by the members of the Vent-Free Gas Products Alliance. One could therefore question it's standing as an independent and unbiased report.

(1.) They are advertised as vent-free, unvented, and ventless gas space heaters.

These variations on product description are provided solely for identification purposes. They all mean the same thing. No vent for the exhaust of combustion products to the outside of the building. 100% Of the products of combustion are delivered into the home. This is the heart of the debate.

(2.) The advertisements promote them as up to 99.9% efficient.

UNDERSTAND WHAT IS INCLUDED IN THE PRODUCTS OF COMBUSTION TO ACHIEVE THIS EFFICIENCY:

99.9% Efficiency is in reference to the theoretically accepted gas combustion efficiencies of natural gas or propane. Generally, under proper installation and operating conditions, 99.9% of the fuel will be consumed. Since there is no vent with these products, 100% of the products of combustion are sent into the home. Products of combustion include heat, water vapor, carbon dioxide, nitrogen dioxide, carbon monoxide and traces of sulpher dioxide, which when condensed with the water vapor forms sulphuric acid with a PH of about 3.5, and particles of unburnt natural gas or propane (.1%).

The initial ignition of any gas burner will not be 99.9% combustion efficient and in the case of some appliances, there will be higher levels of unburnt fuel gas particles and products of incomplete combustion, such as carbon monoxide emitted each time the appliance is fired or shuts down. Therefore one would expect higher levels of fuel particles and carbon monoxide to be generated, into the air in the home, from an appliance that is cycling on and off more frequently.

(3.)Their advertisements further claim to be able to save the consumer up to 60% on installation costs as compared with vented models.

If the average installation cost is $500.00 for a vented gas space heater, they are suggesting the installation costs of an unvented unit, "could be" as low as $200.00. Statistically, this is a false statement. The added costs for labor and materials for either an aluminum chimney liner or installing a short vent through the sidewall does not come close to $300.00 in additional costs on an average installation.

The truth is, the additional materials and labour to vent an appliance may be as high as $150.00 in an average case. That $150.00, is money well spent as this review will show.

(4.)They claim to have been "rigorously" tested to ensure vent-free gas appliances will perform within nationally recognized guidelines for indoor air quality. Even taking into account the higher sensitivities of children, pregnant women, the elderly and those with pre-existing respiratory problems. They claim vent-free appliances operate within established safety guidelines.

THIS CLAIM IS ONE OF MY GREATEST CONCERNS

The tests performed by the AGAR in 1996 were primarily conducted on low Btu input, (10,000 to 15,000) blue flame space heaters, supposedly, for use as supplementary heaters. Most of their tests were thus conducted within a laboratory environment under controlled lab conditions, using appliances set up and fine tuned for ideal performance by trained gas technicians and engineers.

The units being sold today, and installed as you read this review, are not all low Btu input, some are as high as 40,000 Bth/H, the maximum allowed for vent-free products and they are not all blue flame heaters. Many are yellow flame gas log sets, inserts, freestanding stoves and built in zero clearance fireplaces, designed to give the wood fire effect. They are finally, not fine tuned by certified engineering technologists and they are not installed and checked with combustion analyzers for optimum combustion performance.

They're installed and serviced, by average trades people, who make an average living cutting, threading and installing gas pipes. What are the odds of some of these millions of units being installed, serviced or operated improperly? I can assure you, the only answer to that question is, very high.

(Note: There is in fact, some basis of truth, in the safety of low Btu, Blue flame or Plaque type, infra-red heaters, which have less of a tendency to emit high levels of products of combustion, harmful or otherwise. Unfortunately, the Vent-Free Gas Products Alliance has chosen to include all product types. Promoting them equally, under a general category and representing them as a single entity. Therefore this review has to be, as, general with regards to it's scope of product types.)

FACTS: WHAT THE ENVIRONMENTAL PROTECTION AGENCY (EPA) SAYS:

"In addition to environmental tobacco smoke, other sources of combustion products are unvented kerosene and gas space heaters, woodstoves, fireplaces, and gas stoves. The major pollutants released are carbon monoxide, nitrogen dioxide, and particles. Unvented kerosene heaters may also generate acid aerosols."

"Health Effects of Combustion Products"

"Carbon monoxide (CO) is a colorless, odorless gas that interferes with the delivery of oxygen throughout the body. At high concentrations it can cause unconsciousness and death. Lower concentrations can cause a range of symptoms from headaches, dizziness, weakness, nausea, confusion, and disorientation, to fatigue in healthy people and episodes of increased chest pain in people with chronic heart disease. The symptoms of carbon monoxide poisoning are sometimes confused with the flu or food poisoning. Fetuses, infants, elderly people, and people with anemia or with a history of heart or respiratory disease can be especially sensitive to carbon monoxide exposures."

"Nitrogen dioxide (NO2) is a colorless, odorless gas that irritates the mucous membranes in the eye, nose, and throat and causes shortness of breath after exposure to high concentrations. There is evidence that high concentrations or continued exposure to low levels of nitrogen dioxide increases the risk of respiratory infection; there is also evidence from animal studies that repeated exposures to elevated nitrogen dioxide levels may lead, or contribute, to the development of lung disease such as emphysema. People at particular risk from exposure to nitrogen dioxide include children and individuals with asthma and other respiratory diseases."

"Particles, released when fuels are incompletely burned, can lodge in the lungs and irritate or damage lung tissue. A number of pollutants, including radon and benzo(a)pyrene, both of which can cause cancer, attach to small particles that are inhaled and then carried deep into the lung."

"Reducing Exposure to Combustion Products in Homes"

"Take special precautions when operating fuel-burning unvented space heaters." Source: EPA

(5.)They state in at least one brochure published by the Vent-Free Gas Products Alliance, that "there's no need to open a window when a vent-free gas appliance is operating."

FACTS: What EPA Says:

"Consider potential effects of indoor air pollution if you use an unvented kerosene or gas space heater. Follow the manufacturer's directions, especially instructions on the proper fuel and keeping the heater properly adjusted. A persistent yellow-tipped flame is generally an indicator of maladjustment and increased pollutant emissions. While a space heater is in use, open a door from the room where the heater is located to the rest of the house and open a window slightly."

The EPA's sound advice is in direct conflict with the Vent-Free Gas Product Alliance statements.

If we follow the VFGPA's advice about not opening a window, we increase the chances of consuming oxygen in the room containing the unvented appliance. We also increase the pollution levels in the room.

If we follow the advice of the EPA and open the window slightly, how much more fuel will we need to burn to offset the incoming cold air? What has just happened to fuel savings and operating costs? It is certainly no longer 99.9% efficient. Fuel savings go out the open window. Where is the advantage of having purchased a vent-free gas heater? A vented heater does not require an open window when it's being operated.

(6.) The Vent-Free Gas Products Alliance has a website in which they have posted their response to an extremely critical article published by Popular Science. One of their comments there reads as follows; "In addition, based upon data available from manufacturers of vent-free gas products, to date, the industry is not aware of any recorded deaths attributed to the emissions of a vent-free gas product that is equipped with an Oxygen Detection Safety Pilot (ODS) (see more on the ODS below).
Facts:

In March 2006 a 14 year old girl and her family pet dog were found dead by her parents, in their home, and the cause was directly attributed to a incorrectly adjusted gas regulator and installer error, on an unvented gas fireplace. That fireplace was equipped with a functioning Oxygen Detection Safety Pilot (ODS) which does not detect carbon monoxide due to improper gas manifold pressures. Although the matter is still before the courts, the licensed gas installer is facing a prison sentence for negligence causing death.

The U.S. Consumer Product Safety Commission (CPSC) estimates an average of 207 people died each year, between the five years beginning in 1995 and through 1999, as a direct result of unintentional carbon monoxide poisoning, relating to consumer products. 49% Were directly related to natural gas and propane heating systems with an additional 19% unspecified gas heating systems. The CPSC has never tracked the specific types of gas heaters involved by either vented or unvented.

The U.S. CPSC further estimates an average of 10,200 people per year, were treated in emergency rooms across the United States for each of the five years, 1995 through 1999, for unintentional carbon monoxide poisoning caused by consumer products. Approximately 78% of these cases were attributed to natural gas and propane heating systems. Unfortunately, their study did not break down the types of heating systems between vented and unvented.

These estimates of deaths and injuries to American men, women and children are thought to be low, due to cases which may have gone undiagnosed and do not include statistics for carbon monoxide poisoning related to vehicles.

Statistics can be so cold to read, so inhuman sometimes, they're just numbers after all. Let me assure you, there is something painful to me, about reading these statistics, particularly on the death ages of children, which are presented for cold scientific purposes. So when I write of the potential deaths of entire families, I think men, women and children.

(7.) The Vent-Free Gas Products Alliance claim that their safety record dates back. "This data covers a 20-year history during which more than eight million units were sold in the U.S."

Facts:

Figuratively speaking, I travelled back in time via the internet archives, to see whether there were any problems with unvented gas space heaters.

Issued January 15, 2002 by the U.S. Consumer Product Safety Commission.

CPSC Offers Tips to Prevent Home Fires Caused by Space Heaters

Devices Associated with 21,800 Fires and 300 Deaths Annually

WASHINGTON, D.C. - As fire departments across the country battle winter home fires, the U.S. Consumer Product Safety Commission (CPSC) reminds consumers to demonstrate care when purchasing and using space heaters. CPSC estimates that space heaters, including both fixed and portable heaters, are associated with about 21,800 residential fires every year. About 300 people die each year in fires started by these heaters.

Fuel-burning space heaters also can cause carbon monoxide poisoning and indoor air pollution, because of improper venting or incomplete combustion.

"We're still seeing too many space heater fires," said CPSC Acting Chairman Thomas Moore. "While CPSC has worked hard with industry to improve safety standards for space heaters, consumers must exercise care in their purchase and use."

"Consumers should be aware that older space heaters might not meet the newer safety standards. The CPSC has worked to upgrade the industry standards on electric, kerosene and unvented gas space heaters. An automatic cut-off device is now required, which turns off electric or kerosene heaters if they tip over. More guarding around the heating coils of electric heaters and the burner of kerosene heaters also is required to prevent fires. CPSC worked to upgrade the industry standard on unvented gas heaters, as well, to provide an oxygen depletion sensor to shut off the heater if the oxygen level drops too low."

From 1985 I found this announcement:

"The U.S. Consumer Product Safety Commission estimates that there were 115 deaths due to carbon monoxide poisoning from gas-fired space heaters in 1985, the last year for which complete statistics are available."

"CPSC said consumers should always refer to their owner's manual for the proper installation, operation and periodic maintenance of gas-fired heaters, whether they are vented or unvented. If there is no manual available, contact the manufacturer or seek expert advice from your local gas company before installing.

In 1983, which is less than their stated 20 years of safety there was this bulletin:

"WASHINGTON, D.C. -- The Consumer Product Safety Commission today issued an alert to citizens, local and State officials, inspectors and fire marshals, concerning the large number of accidental deaths from carbon monoxide poisoning which occur every year."

"Nearly 300 people die unnecessarily from carbon monoxide (CO) poisoning, a majority because of improperly vented gas appliances. Most of these deaths occur in the winter months during the peak heating season. The deaths are associated with gas furnaces, ovens and ranges, and particularly space heaters, which alone cause approximately 170 deaths each year. Approximately 40 of these deaths are associated with unvented gas space heaters; that is, heaters which do not need to be vented to the outside of the house."

From as far back as 1980 I found this announcement from the U.S. CPSC:

"The (new) standard, however, will not affect the estimated 7.6 million unvented gas space heaters now in use. Consumers already using these heaters should heed the following safety rules:

Never use an unvented gas heater without first opening a window or otherwise providing fresh air.

Be particularly careful about using unvented gas heaters in sleeping quarters. Most carbon monoxide deaths involving these heaters occur while the victim sleeps. Adequate ventilation and maintenance are musts.

"If you are pregnant or have anemia or heart or lung disease, you are particularly vulnerable to carbon monoxide. People who have been drinking or those who reside at high altitudes also must be particularly alert for the symptoms of carbon monoxide poisoning."

In other words, there were more than 7 million units already in the market in 1980 which were considered dangerous, because they weren't equipped with back up safety controls and because they weren't meeting modern requirements. I presume many of these old heaters are still out there operating under who knows what kind of condition.

(8.) The Vent-Free Alliance would like to point out that since around 1980-81 changes were made to standards which mandated the inclusion of a little device called an oxygen depletion sensor (ODS). If an unvented space heater is not supplied with fresh air from outside, the oxygen levels in the room decrease. As the oxygen decreases, incomplete combustion will begin to take place and can generate deadly levels of carbon monoxide. They claim through their literature and their website that;

"a vent-free gas heater will not operate at an oxygen level below 18 percent. This is because the ODS system, which is an extremely precise safety feature unique to vent-free gas appliances, reacts to a decrease in a room's oxygen supply in a manner that shuts off the gas supply to the appliance. The gas pilot burns normally when it is exposed to normal air (20.9 percent oxygen), but in the unlikely case when the oxygen level in a room drops to a predetermined level, established by the national safety standard to be 18 percent, the pilot flame lifts off of the flame-proving thermocouple causing the gas valve to close. In other words, by shutting off the gas supply it "fails safe" and the appliance cannot be manually re-ignited until the room air is back to normal at (18 percent oxygen or higher). As previously noted, all vent-free gas products certified to the national safety standard incorporate an ODS."

FACTS:

I have personally tested these $20.00 devices under ideal lab conditions and found that their factory set points of shutting off at 18% oxygen will wander. Conducting tests on twelve (12), 30,000 Btu/H plus, unvented gas log sets, that with at least three units, the oxygen level in the test enclosure could be lowered to as little as 15.9% before the device was triggered to shut down the gas supply to the burner. That's a far cry from being "extremely precise", as they claim. Furthermore, the carbon monoxide levels in the room were well in excess of 500 parts per million by the time the ODS system responded. That represents a 25% percent failure rate out of 12 samples. Or put another way, 3 out of 12 families potentially poisoned.

The ODS pilot system is not an extremely precise device. The precision of the device is directly related to the position of the thermocouple, if this is bent or adjusted in any way, the calibration is lost. People aren't supposed to adjust the calibration of these important safety devices, but they will, and they do. In our tests, the samples were virgin production samples straight out of the box and fresh off of the assembly line from the manufacturer, with no adjustments by us.

Last, and perhaps most importantly, the ODS system is at floor level, generally below the burner and less than 10" above the floor. The oxygen levels at that height would remain relatively high, as the rest of the available oxygen in the room is depleted higher up. The test enclosure we used proved this important point, as we were able to sample the air from the top of the chamber and at various points down to floor level. Carbon monoxide contained within the hot flue gases stratifies at the higher levels of the room. A CO level of 25 parts per million may be read 10" from the floor, while the CO levels at five feet may read 200 ppm. This is also a reason why I don't believe in mounting CO detectors on electrical outlets close to the floor, but, that's another issue.

(9.) The Vent-Free Alliance almost made me laugh with the following assertion on their website, if the issue weren't so serious;

"Many people in cold climates use humidifiers for added indoor moisture due to a reduction in the relative humidity when it is cold outdoors. While vent-free gas heating products are not intended to replace humidifiers, they do perform a similar function by releasing a small quantity of water vapor, providing increased comfort when it's cold. In doing so, vent-free products become a source of added comfort rather than a source of concern for most homes.

Vent-free products become a source of added comfort, by adding gallons of water vapor to the home environment? Did they happen to mention where that water vapor is going to condense? On walls and windows of course. Did they acknowledge that the condensation from water vapor in combustion gases is mildly acidic?

The Vent-Free Alliance has made a statement on states and countries which continue to ban unvented gas appliances for safety reasons. Canada is named as one of them. They deny it, saying that some of Canada's western provinces still allow them and even asked them for their technical assistance in order to understand vent-free technology. Nothing could be further from the truth. They are approved, with specific conditions, in 47 states and they are still banned for sale entirely in Canada. British Columbia did experiment with a trial period, under a tightly monitored and time limited period and concluded the risks were too high. The engineer for the British Columbia government, told me, "it was one of the greatest mistakes he ever made.

California, Wisconsin, and New York City continue to agree with Canada's position on totally banning them for sale within their jurisdictions, out of concerns for the health of their citizens.

Statistics on deaths and injuries, as well as warnings about the use of unvented gas appliances are supported by The U.S. Environmental Protection Agency (EPA), the American Lung Association (ALA), The Center for Disease Control (CDC), The Consumer Product Safety Commission (CPSC) and The Mayo Clinic.

The only group that seems to be 100% behind them are the manufacturing members of the Vent-Free Gas Products Alliance, distributors who wholesale them and the dealers who sell and install them. As one of their brochures says, "Your accountant will thank you too...Vent-Free; An opportunity to increase...profit to your bottom line." I guess that's what this debate is really all about.

If you've already got one in your home, have it tested by a professional. Someone who has read the specific installation codes for these products and can ensure the unit is properly sized to national guidelines, correctly installed, well ventilated and functioning safely. If you can afford to, have it removed and have a vented model installed.

Let's be honest, all gas appliances have the inherent ability to create carbon monoxide and other pollutants, but, doesn't a properly maintained vent system just seem more logical? If something goes wrong, in a vented appliance, there's a better than average chance that harmful products of combustion will be sent outside. Where else can they go with an unvented appliance, but, into your home?

Please use common sense and vent products of combustion from your home. You will never regret having a properly vented heater in your home, you very well may regret an unvented gas appliance... some day.

Be safe.

The Gasman


Edited by VM Smith (12/16/06 12:40 AM)
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#497248 --- 12/16/06 02:28 PM Re: Natural Gas Stoves
Dakota Offline
Senior Member

Registered: 07/25/05
Posts: 989
Loc: Who? Me?
_________________________
Lead me, follow me, or get out of my way.
- General George Patton Jr



Potius mori quam foedari

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#497249 --- 12/17/06 06:08 PM Re: Natural Gas Stoves
VM Smith Offline
Diamond Member

Registered: 11/28/05
Posts: 38160
Loc: Ship of Fools
"Dealers in the U.S. admit these products are an easy sell, when they ask the trusting consumer the wrong questions: i.e., “What would you rather buy? This vented gas log set for $500, which is 99.9% efficient, or this direct vent zero clearance fireplace for $2,200, which is only 80% efficient? (Quote partially taken from retailer David Coppinger in the October issue of Hearth & Home.)

If these dealers were being absolutely truthful with their customers, the question should come out: “For $500, you can have this unvented gas log that will throw off heat, water vapour (adding to the humidity levels in the home), traces of carbon monoxide, sulphur dioxide and nitrous oxides, and may, if not maintained, operated or installed correctly, kill you and your family in your sleep. Or, you can have this direct vent fireplace that uses outside air in a sealed combustion system, and only delivers heat into your home, allowing you and your family to sleep in safety for $2,200.”

I guess it’s all in how you ask the question.

Perhaps one of the better quotes I have read in this debate came from one of the many opponents to unvented, Jim Hermann of The Earth Stove, who said: “You don’t need a scientist, you need a psychiatrist.”
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