Gas ventless burners


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Old 02-04-07, 08:49 AM
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Gas ventless burners

Recently I've read a couple of threads where the dangers of ventless gas log burners have been discussed. Several posters have mentioned deadly dangers from excess CO2.
I mentioned this to my son as he recently had a ventless gas logburner installed in his vacation home. His response to me was that if it is so dangerous "why are they allowed and how come my unvented gas range and gas oven aren't a problem"? I didn't have an answer. Any help?
 
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Old 02-06-07, 02:48 AM
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Originally Posted by Wayne Mitchell View Post
Recently I've read a couple of threads where the dangers of ventless gas log burners have been discussed. Several posters have mentioned deadly dangers from excess CO2.
First and foremost, it has nothing to do with excess CO2. It's excess CO. CO2 is carbon dioxide in which makes up approximately .04% of the air we breath.

Carbon monoxide is the hazard here. Even prolonged exposure of a minimal amount of CO can prohibit the oxygen exchange in you blood cells.

Originally Posted by Wayne Mitchell View Post
His response to me was that if it is so dangerous "why are they allowed and how come my unvented gas range and gas oven aren't a problem"? I didn't have an answer. Any help?
This question is asked often.

First: Just because the gas range in itself is doesn't have a vent doesn't mean it's not required to have a vent hood installed above it. Depending on jurisdiction, you can not (legally) have a gas range with out a vent hood.

Second, a gas range (in it's proper use) isn't designed to heat, it's designed to cook. You are not going to turn it on in the morning and run it all day left unattended to heat the house.

A gas log set can be used to heat where it could be left for hours on end and forgot about.

Additionally, gas logs burn dirtier than a gas range. Ranges should have a nice blue flame. Gas logs give a yellow sooty flame to resemble burning wood.
 
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Old 02-06-07, 08:11 AM
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I did a little researching to try to answer my own question. You're right about CO being the issue. It was a typo on my part.

Here's what I was able to find out:

Carbon monoxide is produced as a byproduct of the combustion process. There is disagreement on whether any CO in the home is acceptable.

Water vapor is as much of an issue as is CO.

Most areas consider ventless gas heaters to be safe when properly sized and maintained. Burners have been improved to burn more efficiently. Ventless gas heaters built after the late 80's must have an ODS (oxygen depletion sensor) installed. If oxygen levels fall below that required for efficient combustion the ODS is designed to shut off the device.

While there have been many deaths attributed to portable heaters and deaths caused by CO poisoning from poorly maintained furnaces, purportedly there have been no deaths blamed on ventless gas heaters. That was from an industry source - hence the "purported".

The CPSC recommends that spaces with ventless gas heaters have a CO detector.

Like so many controversial subjects there is all sort of information, wrong information, misinformation and spun information depending on the source.

My own conclusion is that they probably are safe if the operating guidelines are followed. I wouldn't install one in my bedroom and I would certainly have a CO detector nearby.

BTW - I have operated gas ovens on low heat for hours on end (ribs, brisket, turkey). Unlike a thermostat controlled gas heater, the oven burns constantly.
 
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Old 02-06-07, 09:20 AM
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Some more info -

Apparently ventless gas heaters got a bad reputation when they were first introduced and the CPSC moved to have them banned. According to the CPSC site they became aware that ODS equipped heaters had been used safely in Europe for years and they withdrew their objection, moving instead to mandate that US manufacturers be required to install ODS' on their products.

CPSC statistics indicate that there were on average (1999-2002), 85 deaths per year attributed to CO poisoning from heating systems, ranges, ovens and water heaters. The CPSC site does not list any CO poisoning deaths during that period that were attributed to ventless devices.

For me the bottom line is that if you burn gas, get a CO monitor.
 
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Old 02-06-07, 11:20 AM
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Gel Fuel?

Have been thinking of adding fireplace to liv. room. Ventless gas, Electric? Not sure yet, leaning to the ventless to avoid major probs with flue local and cost.
Channel surfing the other day and caught info/sale bit on fireplace (ventless) with gel fuel cans. Looked to me the can(s) were placed behind logs & lit, producing bunsin burner looking flame. Very liitle heat from this, more of a decore thing I would think.
Anybody out there tried these? Was wondering on fuel cost, odor & YES safety?
Thanks
 
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Old 02-06-07, 04:07 PM
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Better let these gel fuel things prove themselves first. I have a set of ventless gas logs, and enjoy the heat it produces. When I bought it the lady cranked up a set of each for me to look at. The vented flames danced alot and it was prettier, but I didn't want "pretty", I wanted heat. I have a small 50 gallon propane tank and it lasts at least a full winter and then some with the logs being the main thing attached to it. I have a dual fuel generator I run off propane, and an emergency gas stove in the basement, but they are seldom used, and have no pilots activated.
 
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Old 02-06-07, 04:38 PM
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Wayne, while I'm not going to dispute your last two posts, this is my take.

ODS equipted heaters are a step in the right direction, but that will only shut down the burner if it is starving for oxygen. It does not do anything if there is excessive CO amounts. In my career as both emergency services and gas related fields I've done more than my share of CO investigations. I have seen CO levels be unsafe at 70 ppm and O2 levels be safe at over 20% (normal atmospheric levels is at 21% O2).

I know many states do not allow them. I work in NY where they are allowed. I have installed several of these. Many people get them because they are readily available in big box stores at attractive prices. What people don't understand is the restrictions and hazards associated with them.

I personally am against them despite what code or law says. I try to educate people the best I can and let them make the determination.
 
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Old 02-06-07, 06:02 PM
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I am not familiar with vented gas appliances but unvented, yes. I can tell you that unvented gas appliances increase the carbon dioxide concentration in a dwelling from an initial 340 ppm (outdoor concentration) to 1500 ppm or higher. I consider CO2 as a pollutant. People can be affected at high concentrations that may not be readily seen. A family of four in a 1500 square foot dwelling that is well sealed, will produce a concentration of 800 to 1000 ppm through their breath. I have a CO2 monitor that gives me a continous digital readout of 550 ppm on average and that is with one person in the house of the same square footage. So adding unvented appliances will add more CO2.
Being as we expell CO2, it would seem prudent to keep levels as low as possible. The short term effects on humans exposed to levels of about 5,000 to 10,000 ppm are fainting and nausea. Death can occur at 20,000 ppm. But no one is studing the long term effects at lower concentrations on humans. But Science has noted the effects seen on our weather and the melting of the ice caps from excess commercial pollution which contains a lot of CO2.

I used to have one of these gas heaters in my finished basement that also contained my salt water fish tank. When I first got into the hobby, I had a difficult time trying to maintain the pH of the water as it was always dropping more then it should even after adding buffer to raise it.
So after reading up on CO2 and its effects on pH, I purchased the CO2 monitor to perform some testing and submitted my results to an online fish magazine which published my findings.

I disconnected the unvented gas heater and now use electric heat. So at this time, I just feel it can be unhealthy to use unvented appliances. My home has an unvented gas range and oven and I installed a fresh air intake in my basement and I turn the kitchen exhaust fan on, whenever I do some cooking.
 
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Old 02-06-07, 06:57 PM
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rjordan392

Wow 20,000 ppm of co2! Never seen heard of anybody dieing from co2! co2 is a Sergent indicator that other pollutants might be at high levels.
 
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Old 02-06-07, 07:49 PM
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Wink

Ventless gas heaters built after the late 80's must have an ODS (oxygen depletion sensor) installed. If oxygen levels fall below that required for efficient combustion the ODS is designed to shut off the device.

AH yes but by then you can be dead from the CO.

Also check out how many states by law you cant sell ventless heaters
 
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Old 02-07-07, 03:46 AM
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Airman,
The 20,000 ppm data was retrieved from an article authored by air quality experts. In the British Isle's, they set a 5000 ppm maximun exposure to 5000 ppm over an 8 hour period. I don't think this country has an exposure limit because we did not sign the Kyota treaty to cut back on high emissions.
Actually what happens is, as CO2 levels increase, the ratio of oxygen to carbon dioxide goes out of balance. Now, humans are breathing in more of the very thing our bodies are expelling. This is a concern in any sealed occupancy.
The highest concentration that I seen in my home was 1500 ppm with the oven on for a couple of hours and the exhaust fan turned off.

As far as I know, no data is being collected on the effects of excess CO2 on pregnant women. One would tend to think it probally possible that the fetus may be affected. Corporate America is not concerned about CO2, but now the President is under pressure to do something about it. In recent appearances, he stated that this country must look for alternative fuels, not only to reduce our dependancy on oil but also to help reduce emissions.

So to control concentrations of CO2, people should have a fresh air intake added to their heating and cooling systems and operate exhaust fans whenever an unvented gas appliance is used.
 
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Old 02-07-07, 05:08 AM
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co2 ASHRAE 1000, HWC 3,500, ACGIH 5,000, RAL 800 all are ppm.
 
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Old 02-07-07, 05:27 AM
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I know what ASHRAE means but the other abbrevations I am not familiar with. Do the others mean maximum and in referance to what?
 

Last edited by rjordan392; 02-07-07 at 05:45 AM.
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Old 02-07-07, 08:38 AM
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I'm not trying to argue for (or against) ventless heaters. I don't own one and have no intention of buying one although I now believe that they are safe to use within the guidelines provided by the CPSC and the industry. My point was that posting "don't use one" does little to inform a person posting looking for information.

If you read the entirety of my post, I stated that the CPSC (Consumer Product Safety Commission) recommended that CO detectors be installed wherever any gas burning appliance is in use.

I also posted that there have been numerous deaths reported caused by "safe", vented gas burning devices.

The ODS is designed to shut off the burner. The CO detector is designed to warn of unsafe CO levels. Apparently, both the industry and the CPSC feel that air exchange in a typical house is more than adequate to prevent CO build up from a properly sized and maintained burner.

According to a 2004(5) CPSC report, 42 states currently allow the installation and use of ventless burners. California and New York are revisiting that, but not to ban them but to toughen the standards. Other states are leaning toward allowing them.

I also posted that there have been numerous deaths reported caused by "safe", vented gas burning devices. I could find nothing that indicated any deaths or serious injuries blamed on unvented gas heaters although I found one site that said 10 people had died, the author gave no source for that number and it appears to be in conflict with the CPSC numbers. It is possible that the CPSC has lumped CO deaths into a "portable heater" category but it appears that those deaths were fire related. I did find one case where a woman was reportedly sickened by a faulty gas heater, but interestingly she was unable to find a lawyer that would take her case. There was no indication whether the device was defective or installed incorrectly.

Chandler - Why in he** would anyone want gas heat in Georgia? Just bottle up some August and open it in January.
 
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Old 02-07-07, 10:10 AM
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So that we do not stray into confusion, the discussion is about possible CO (carbon monoxide) and CO2 (carbon dioxide) accumulations to the point where both become unhealthy. Most homes with good air exchange and properly working burners won't see any CO registered on their monitors. But with an unvented Gas heater and a well sealed house without sufficient air exchange, then CO2 (carbon dioxide) can reach levels to be unhealthy over the long term if levels stay near constant.
The ambient concentration is 340 ppm CO2. So if the concentration in the home is 1200 to 1500 ppm or more; whose to say it's not unhealthy. So with that, I am maintaining it at 550 ppm just for piece of mind.
 
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Old 02-07-07, 12:13 PM
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Don't want to give offense, but the discussion is about the danger presented by CO (not CO2) generated as a byproduct of combustion in ventless gas heaters. CO2 mentioned in the OP was a brain fart on my part.
 
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Old 02-07-07, 04:34 PM
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I added CO2 to the thread because people are ignoring it. Admittedly, it takes a lot more of CO2 to make one ill then CO. I don't believe we should give the impression that it should be ignored. All products of combustion should be vented or at least have mechanically supplied fresh air coming in to dilute the CO2 and maintain oxygen levels and not depend on air leakage throughout the house to replemish it. In past threads about CO, people are walking away thinking that if they don't have a CO problem, then they feel safe. This is not true. The problem can be more apparant with homes that are well sealed and the homeowner decides to shut down the furnace air intake device and fire up an unvented gas heater for supplement heat.
Even if the gas heater works as it should, a much higher concentration of CO2 will accumulate.
 
 

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