question for anyone with HVAC exp.

[Pactivist]

I have a Bryant plus 90 furnace. The exhaust from this runs out through PVC pipe, and is only warm to the touch. My furnace is actually rated at 93% efficiency which leads me to wonder, what is the composition of the exhaust gasses from my heater? I know that carbon monoxide is a byproduct of inefficient combustion of hydrocarbons, well this is some fairly efficient burning, so I was curious to know if my exhaust is more CO2 or CO? would it be safe to vent it into my room? would it be worth anything if I did? Just a thought.
peAce,
pacT

 

[cabanetforester]

I have no HVAC experience whatsoever..Sorry thought I should get that out of the way.

Did you search for emissions info on your model? There might be some fairly detailed specs in a pdf or something.

You could collect some of those gases in a tube with a small vacuum hand pump like those used for bleeding brakes lines, etc.

I know they make cheap disposable co2 testers, not sure about other types of gas testers.

Sounds like a cool idea with a few possibilities. If you could draw from that flu via compressor, clean and dry the air then into a small tank @ 50-75 psi in one of those portable tanks maybe. Thread a bung on the tank that can accept your standard co2 tank fittings and use something like the cap ppm-3/ solenoid to control it.

I would also want to make dam sure I knew exactly what was in that flu gas and at what proportions.

This is used for heating only? So a winter setup only then?

Sounds like a good idea to me.

 

[HeadyPete]

Are you joking?!?!?!?!

Headlines at 11....1 body found asphyxiated....evidence of tampering with the furnace exhaust....possible suicide.

There is also a ton of moisture in that exhaust and from what I've been told by a furnace guy, it is way acidic.

I would not bother fucking with that unless you have a death wish.

 

[Bababooey]

I've head that the sulfur in gas turns to sulfur dioxide in the exhaust. Is that what makes it acidic? But I wonder, some co2 generators can be modified to run on the natural gas from your home. Do they get rid or separate out the sulfur dioxide somehow?

 

[Guest]

Ever wonder why Code requires venting to the outside? Usually every winter we lose a bunch of folks in this world that use NON VENTED heating sources and wind up dead, I see all to many articles in the news every winter.

be Safe

Ty-Stik

 

[HeadyPete]

I believe you are correct, baba.

Natural gas combustion produces Carbon Dioxide, carbon monoxide, sulphur dioxide and Nitrous oxides. http://www.uniongas.com/aboutus/safety/2006 NG MSDS English Version Spectra Energy.pdf

SO2 has a ph of 1.81, so it is extremely acidic. http://en.wikipedia.org/wiki/SO2

 

[Pactivist]

cool I was just wondering, I'm obviously not an HVAC tech. Thanks for the info.

 

[THCV]

well, i have NG burners INSIDE my sealed room and i am still alive. If you have an efficient NG furnace, you could try setting it up to vent into your space temporarily and put a $20 carbon monoxide alarm in the room. it's the CO that kills people. if your furnace is burning clean, it'll be mostly CO2, and as long as you DO NOT have a sealed space i would bet it's ok. but then again, people almost always warn against it. nevertheless, there's plenty of co2 going out your roof, seems a shame not to put it to work, but safely.

ps i also have open flame NG fireplaces in my home, and i run them with the FLUE CLOSED! tested CO2 ppms in my house, they never went above 800 ppm but i have a drafty house, so it's impossible to build up too much (and also near impossible to heat well!).

 

[SoEx]

well, i have NG burners INSIDE my sealed room and i am still alive. If you have an efficient NG furnace, you could try setting it up to vent into your space temporarily and put a $20 carbon monoxide alarm in the room. it's the CO that kills people. if your furnace is burning clean, it'll be mostly CO2, and as long as you DO NOT have a sealed space i would bet it's ok. but then again, people almost always warn against it. nevertheless, there's plenty of co2 going out your roof, seems a shame not to put it to work, but safely.

It's really not worth the risk, I don't believe.

CO is not really something to fuck with. In sufficient concentrations you won't notice you're breathing in CO, you'll quickly pass out, and then be trapped in a room with growing CO concentrations. This also is hazardous for anyone trying to rescue you -- people die trying to get people out of high-CO areas all the time.

 

[THCV]

found a piece that covers it in depth:

Monitoring of the CO level during CO2 supplementation

what it boils down to is that you should be monitoring both co2 and co, and switch flue from feeding your room back to exhaust mode if either gas gets above set levels, which would be much lower than dangerous levels.

all it takes is a little application of technology. we shouldn't be afraid of that here. we are generally willing to take risks-like 100 gallons of water sitting next to 1000s of watts of power in an earthquake zone, etc etc--and you can feel very comfortable with these risks if you DESIGN your system with safety in mind. Of course, it gets more expensive--i haven't seen a growroom co2 controller/monitor that monitors co also, but i believe they exist on the professional megagreenhouse level, and they are no doubt expensive. and once you are playing that game, you'll probably get "real" burners. But they are basically the same thing, although NG furnaces burn at a higher temp i believe. That probably changes the gas output composition, but i am not sure how.

If you are not into taking managed risks, definitely avoid it. But it isn't black magic, and your furnace is already burning all winter, so it would be pretty awesome if someone on ICMag did this idea up right. I would volunteer, but i already have 2 burners!

 

[SoEx]

found a piece that covers it in depth:

Monitoring of the CO level during CO2 supplementation

what it boils down to is that you should be monitoring both co2 and co, and switch flue from feeding your room back to exhaust mode if either gas gets above set levels, which would be much lower than dangerous levels.

all it takes is a little application of technology. we shouldn't be afraid of that here. we are generally willing to take risks-like 100 gallons of water sitting next to 1000s of watts of power in an earthquake zone, etc etc--and you can feel very comfortable with these risks if you DESIGN your system with safety in mind. Of course, it gets more expensive--i haven't seen a growroom co2 controller/monitor that monitors co also, but i believe they exist on the professional megagreenhouse level, and they are no doubt expensive. and once you are playing that game, you'll probably get "real" burners. But they are basically the same thing, although NG furnaces burn at a higher temp i believe. That probably changes the gas output composition, but i am not sure how.

If you are not into taking managed risks, definitely avoid it. But it isn't black magic, and your furnace is already burning all winter, so it would be pretty awesome if someone on ICMag did this idea up right. I would volunteer, but i already have 2 burners!

That's because I know, at worst, water will spill, a GFCI will trip, and I might lose a light or some equipment. With CO you're taking a managed risk with your life -- not so easily replaceable. I'm just saying to please be careful and make sure you know what you're getting in to.

 

[THCV]

ok, after this thread, for the benefits of the community, i went and bought a $50 co monitor that has a digital readout with the ppm of co it detects. emits a piercing alarm if the co goes above 70 or more ppm, has a 9v battery backup but runs on AC. I put it in my room with the co2 burner keeping the room at 1500ppm. It detected exactly 0 ppm, that's zero. I left it in for half an hour, still zero. So even though i have burners in the room burning the same NG your furnace is burning, venting straight into the room, i have zero ppm co. Food for thought for the furnace experiment. Just get a co meter. You'll know very quickly whether to abort.

 

[HeadyPete]

CO is not the only toxic part of NG.

800 ppm? That is over toxic levels.

Carbon Monoxide produces the following physiological effects on people exposed to the concentrations shown:

Concentration of CO in air


Inhalation time and toxic developed

50 parts per million (ppm)


Safety level as specified by the Health and Safety Executive

200 PPM


Slight headache within 2-3 hours

400 PPM


Frontal headache within 1-2 hours, becoming widespread in 3 hours

800 PPM


Dizziness, nausea, convulsions within 45 minutes, insensible in 2 hours

Carbon Monoxide poisons by entering the lungs via the normal breathing mechanism and displacing oxygen from the bloodstream. Interruption of the normal supply of oxygen puts at risk the functions of the heart, brain and other vital functions of the body.

The mechanisms by which carbon monoxide produces toxic effects are not yet fully understood, but haemoglobin, myoglobin, and mitochondrial cytochrome oxidase are thought to be compromised. Treatment largely consists of administering 100% oxygen or hyperbaric oxygen therapy, although the optimum treatment remains controversial.[19] Domestic carbon monoxide poisoning can be prevented by the use of household carbon monoxide detectors.

Carbon monoxide is a significantly toxic gas and has no odor or color. It is the most common type of fatal poisoning in many countries.[18] Exposures can lead to significant toxicity of the central nervous system and heart. Following poisoning, long-term sequelae often occur. Carbon monoxide can also have severe effects on the fetus of a pregnant woman. Symptoms of mild poisoning include headaches and dizziness at concentrations less than 100 ppm. Concentrations as low as 667 ppm can cause up to 50% of the body's haemoglobin to be converted to carboxy-haemoglobin (HbCO). Carboxy-haemoglobin is quite stable but this change is reversible. Carboxy-haemoglobin is ineffective for delivering oxygen, resulting in some body parts not receiving oxygen needed. As a result, exposures of this level can be life-threatening. In the United States, OSHA limits long-term workplace exposure levels to 50 ppm.

 

[THCV]

yes--of CO. As I said, i read 800ppm of CO2 in my living room, not very different than what you get with two people sitting in a room for a bit. CO2. As for CO, zero is all i have measured so far..

 

[Pactivist]

well since THCV's posts I have decided to actually test the output of my furnace. It may take me a minute to get this done but I will post my results as soon as I have the gasses tested. I am of the mind, and I feel that THCV agrees that - like I said in the original question, "Innefficient burning of hydrocarbons = CO" , "efficient burning of hydrocarbons = CO2" and both produce water vapor. Being an aircraft mechanic, I am very familiar with the byproducts of combustion, especially when it is done with little regard to efficiency, as in internal combustion engines.
But all of you who have LP CO2 burners are doing basically the same thing here is something for everyone to read.
The simplest hydrocarbon , methane is a gas with a chemical formula of CH4.


Methane
The carbon atom central to the methane molecule has 4 valence electrons and thus needs 4 more electrons from four hydrogen atoms to complete its octet. The hydrogen atoms have a 109 degree bond angle giving the molecule a tetrahedral geometry .

A principal component of natural gas, methane is significant . Burning one molecule of methane in the presence of oxygen releases one molecule of CO2[carbon dioxide) and two molecules of H2O (water):


CH4 + 2O2 ---> CO2 + 2H2O

A three-carbon alkane, propane is sometimes derived from other petroleum products during oil or natural gas processing.

Chemical Formula: C3H8

When commonly sold as fuel, it is also known as liquified petroleum gas (LPG or LP gas) and is a mixture of propane with smaller amounts of propylene, butane and butylene, plus an ethyl mercaptan odorant to allow the normally odorless propane to be smelled. It is used as fuel in cooking on many barbecues and portable stoves and in motor vehicles. Propane powers some buses, forklifts, and taxies and is used for heat and cooking in recreational vehicles and campers. In many rural areas of the US, propane is also used in furnaces, water heaters, laundry driers, and other heat-producing appliances. Delivery trucks fill up large tanks that are permanently installed on the property (sometimes called pigs) or exchange bottles of propane.

I know that mercaptans are added to natural gas to produce a detectable odor so that people don't blow themselves up or die of hypoxia as it says here though natural gas is primarily methane.

The primary component of natural gas is methane (CH4), the shortest and lightest hydrocarbon molecule. It also contains heavier gaseous hydrocarbons such as ethane (C2H6), propane (C3H8) and butane (C4H10), as well as other sulfur containing gases, in varying amounts, see also natural gas condensate. Natural gas also contains and is the primary market source of helium.

it is also cleaned prior to being sent to your home

Nitrogen, helium, carbon dioxide and trace amounts of hydrogen sulfide, water and odorants can also be present [2]. Mercury is also present in small amounts in natural gas extracted from some fields[3]. The exact composition of natural gas varies between gas fields.

Organosulfur compounds and hydrogen sulfide are common contaminants which must be removed prior to most uses. Gas with a significant amount of sulfur impurities, such as hydrogen sulfide, is termed sour gas; gas with sulfur or carbon dioxide impurities is acid gas. Processed natural gas that is available to end-users is tasteless and odorless, however, before gas is distributed to end-users, it is odorized by adding small amounts of odorants (mixtures of t-butyl mercaptan, isopropyl mercaptan|thiol, tetrahydrothiophene, dimethyl sulfide and other sulfur compounds), to assist in leak detection. Processed natural gas is, in itself, harmless to the human body, however, natural gas is a simple asphyxiant and can kill if it displaces air to the point where the oxygen content will not support life.

so in the end I believe that natural gas is a cleaner burning fuel than LP. what are you thoughts?
peAce,
pacT

 

[THCV]

Paxtivist, NG is indeed a cleaner burning fuel than LP. Unfortunately, that includes CO2, so LP burners put out more CO2 per BTU of heat than NG. From a heating/global warming perspective, NG is the better fuel, but from a plant greenhouse perspective, LP is actually better for intentionally generating CO2. But taking those tanks in and out of my grow was easily the most suspicious looking move i was making regularly, so i switched to NG. It's cheaper and of course, much easier. A little bit less efficient for CO2 generation, but cleaner burning too.

Glad you are going to test it. Aircraft mechanic, eh? I am not worried at all!! Sounds like you are the right guy to answer this question once and for all. I look forward to seeing your results.