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taracol

foul smell from gas furnace vents

taracol
10 years ago

Please help. We have a gas furnace (only 2 years old) and an odd smell coming from the heat vents. The gas company has checked the heat exchanger and says its fine and their meters do not pick up any gas or carbon monoxide readings.
We have had our furnace installer plus another company come out and go through the furnace and they also find nothing wrong. We had the drip pan cleaned and the water pump for the humidifier replaced. We ran the fan alone to make sure the smell does not occur with only that running to make sure its not anything in the heating ducts. No smell. It only comes on when the heat has not been run in a few days and it only smells for about 15 minutes then it dissapates.
It is a putrid smell and is difficult to describe. It smells like natural gas mixed in with some type of sickeningly sweet smell and something dead to me. Its not gas because no meters pick this up and it doesnt smell like rotten eggs. It is not a dead carcass because it is throughout all ofthe vents and its been going on for over a year. There is nothing else in my home that has a smell that is being picked up by the furnace that would come out of the vents. It also was ran all fall and winter long and no smell- just last April and this April. I know this sounds crazy but I assure you Im not crazy. My family members have also smelled this gross smell. We had the manufacturer (Frigidaire rep) come out and go through the furnace also. He couldnt find anything. The furnace filter is clean as well. Im at my wits end. Please help! Can you think of anything else that it could be that we havent checked or thought of? I dont want to keep living with this smell. We have young children and Im afraid.

Comments (41)

  • mike_home
    10 years ago

    Has the HVAC installer witnessed this smell? If yes, then what was their comment?

    What is the model number of the furnace? How is the exhaust gas from the furnace vented to the outside?

  • taracol
    Original Author
    10 years ago

    The installer is never here when the smell occurs. He was here one time after the smell happened and he smelled it but only faintly. I do not think he is taking me seriously. The installer was supposed to come out to my home this am with the representative from the manufacturer and instead they sent out a regular technician from the installer's company to check for a "dead animal" in my vents. They were supposed to be here to see if we could replicate the smell. The model number of the furnace is C6BA-x36c-c. I am wondering if there are any recalls on this or service tech bulletins. Any assistance you could provide would be greatly appreciated. Thanks!

  • mike_home
    10 years ago

    The model number you provided is for the coil. Do you know the answers to my other questions?

  • taracol
    Original Author
    10 years ago

    Sorry about that. The exhaust gas is vented with PVC piping and is vented out the back of our home. The model number on the furnace is FGD090800507. Thanks

  • ftm_1
    10 years ago

    I'm going to go with mold or fungus of some type. I have the same thing.
    Doesn't matter if its only a couple days or a month between running. When the burner lights, it burns the funk off and smells.
    I installed a UV light over my A-coil, didn't help. Its coming from the burner.

  • taracol
    Original Author
    10 years ago

    It was suggested to me that it may be something being picked up by the return. Can anyone shed any light on this? Im not really sure what this could be?

  • zl700
    10 years ago

    Is it "dirty sock syndrome"?

    Very common, comes from the AC coil

    Here is a link that might be useful: Dirty sock syndrome

  • taracol
    Original Author
    10 years ago

    No, I dont think its dirty sock syndrome. It does not smell musty. Has a putrid smell- almost like a mixture of something dead with rotting fruit (like a sweet smell) mixed with a natural gas.

  • zl700
    10 years ago

    Yes but mold often has a sweet smell.

    Once the spores release the smell dissipates. After growing new and a cycle starts you smell them again.

    My money's on the coil

  • EmilyCooper38
    10 years ago

    Can you let know what you discover? I think we have the smell like you have. We built this house. When we move in the house in first year, I can smell the smell. Since this is a new house, I just can't figure out what it is. We have a 90% high efficiency furnace with AC coil and Honey Well electric filter. I also found that when I notice the smell, the smell is coming from the vents which are mounted on ceiling at "upper" floor.

  • rgs03833
    10 years ago

    OMG... I am so GLAD I searched on Google today.... Anyway, I have the SAME Problem..... My Furnace is GAS.... I have the SAME SWEET SMELL coming out of my Furnace sometimes... At times, I can get a HEADACHE from it, sometimes I COUGH like crazy. It's only happened when the HEAT is on HIGH, I can barely stand it at 72 Degree. We TORE all the VENTS... Return Air and Out, FILTER is BRAND NEW and Checked the Furnace out, the only thing that we haven't done is checking out the BURNING CHAMBER...

    I mean we CLEANED it all out and YES I checked everything, including a NEW Liner in the Chimney and the Intake Cold Air is BRAND NEW. I kept saying that there is a SMELL and sometimes SWEET Smell just like this post here.... Everyone thinks I'm going CRAZY :(

    PLEASE, PLEASE PLEASE, let me know what you find what the problem is.... I bought this house 3 years ago, and each time we Start the Furnace, everything is BURNT out and fine, then this SMELLs comes afterward, and how can some days are fine, then other days we have the SAME SMELL????... It can't be something in the Pipes because we TORE the Darn thing off and CLEANED out....

    No YOU are NOT CRAZY, if you are then I must be CRAZY too for smelling the SAME ODOR !!!

    My suspicions... There must be a Small Hole somewhere in the Burning Chamber or the Metal of the Burning Chamber HEATS up and released an ODOR that normal People can't smell it. Only the sensitive People can Smell this Smell.

    Honestly, I'm beginning to think I'd rather stayed COLD or use an Electric Heater and heat up the ROOMS that I need and forget about the Gas Furnace

    NOTE: My Natural GAS Heater is 80% efficiency and I don't have AC in my GAS Furnace.

    Robert

    This post was edited by rgs03833 on Thu, Dec 26, 13 at 5:04

  • mike_home
    10 years ago

    How old is your furnace? Has a HVAC tech inspected it for a cracked heat exchanger?

  • rgs03833
    10 years ago

    Hi Mike, no I haven't, since I like to do EVERYTHING on my own so I know that I have done it myself and it would help me sleep better at night since I did it myself ;)

    Anyway, that is my Next Task... I will post once I know if that is the case ;)

    Thank you for your Input ;)

    Robert

  • celinemarie
    10 years ago

    I have a similar problem, only the smell is of natural gas and I smell it in the room after the blower/fan (not just the furnace) has run for about 10 minutes. The smell gets stronger the longer it runs. The local energy company and an HVAC contractor have checked out the utility closet gas pipes and furnace and found no gas leaks, yet a combustible gas detector I bought online indicates the presence of gas in my living room, bedroom, etc. after the blower runs. Help!! I am using only space heaters 90% of the time because of this problem (fortunately I live in a small condo where using only space heaters is feasible). The contractor I hired said any gas I'm smelling is unlikely to be at an explosive level, but I'm still nervous about this!

  • mike_home
    10 years ago

    This thread has digressed from the original post, but the type of discussion here merits a comment.

    If you smell gas then you need to call the gas company immediately! The gas company has gas sniffing equipment. It is in their best interest and to find any leak which has the potential of an explosion.

    It is possible the smell is not leaking gas but a poor combustion or venting situation. This may mean a high level of carbon monoxide. This is potentially lethal and again warrants immediate attention!

    If the contractor is says it is not a problem then find a competent contractor!

  • rgs03833
    10 years ago

    Hi,

    OMG... Well 1 Problem SOLVED.... I just found out this weekend... That the Ballast from one of my Light is LEAKING BLACK Liquid out of it, due to HOT / Damaged Ballast. That is Part of the Smell came from.... Since I have Drop Ceilings, and the Fluorescent light was up there, there was NO WAY I was able to see if the Ballast was Damaged, until I open the light itself. Many times I am in a Store like Wal-Mart / Big Box Stores.... I Cough a lot... Now it make sense because most of their lights are Fluorescent and have Ballasts... YES, I am able to Smell BAD Ballast, LOL

    OMG.... Anytime the Heat is On... I smell the Smells like the Original Post here... Plus also it felt like Radiations... Attacking my Head, LOL... But now that Problem is SOLVED....

    Here is Problem Number 2.

    OK, here is the Funny Part.... There is still a Smell Left.... But it doesn't feel like Radiation Attacking me.... Since the Ballast is GONE.... But it only happens on Certain days.... How can my Heater have a Brain and just put out an Odor on Certain Days.... Especially the Past two days since it's SNOWING / COLD outside?

    It's been a Week since my last Post, I have been enjoying my Heater and Sleeps better at night. If there is a CRACK inside my Heater Chamber.... Wouldn't the Smell would come out anytime the Heater is on?

    Also, I put a Large Exhaust Fan in the Attic... Anytime I smell the Smells, I turned it on for about 30 seconds and the Smell will be gone for a while... Air is Great again... I am beginning to think that when the Attic gets Moisture from the Air / Snow some how it seeps into the Roof's Wood... Then released it and when the Heater is on, it disburse through the entire House. Once the House is HEATED UP to about 68+ Degree... The Smell would be gone.

    Another thing I suspect is... I am really sensitive and I can Smell things that Regular People can't smell.... I'm sure the ones that have the same problem with their Gas Furnace would understand. I think when the Galvanized Pipes Heats Up.... It Put out an Odor that most People can't smell it, and only the Sensitive People can smell this Smell.

    I would also like to ADD.... If your Smells like BURNT Electrical or even BURN Plastics / wires, I think you would Experience this as well. Your MOTOR / BLOWER is working Harder than it should.... Like the Intake Air that is Blocked in Certain Room.... You would Experience a Smell in the Furnace that most People can't smell it, because the MOTOR Heats Up because it's working Harder than it should. This is about the Same as I am able to Smell the BAD Ballasts.

    The reason I post all my findings on here is to give / help People like me an Idea of what is happening to some of us. I hope some People would take all the accounts that I have experienced and tell your HVAC Tech to Check.

    I will Post my Final Finding soon I hope!

    Robert

    This post was edited by rgs03833 on Sat, Jan 4, 14 at 5:29

  • mike_home
    10 years ago

    "an Odor on Certain Days.... Especially the Past two days since it's SNOWING / COLD outside"

    Perhaps you have an exhaust venting problem. Could snow be blocking the vent on roof? Very cold air could also make venting more difficult since it is denser than the warm air down at the furnace.

  • rgs03833
    10 years ago

    Hi Mike,

    I have a Dedicated Chimney Liner for my Gas Furnace also, it has a Cap on it as well. It's only about 10 Feet High since my Furnace is in the Attic. Plus, the Furnace Exhaust Fan would Shut Down if any thing is Blocked or the Exhaust is NOT doing its Job.

    Also, the Chamber where the AIR is heating up is Separate from the Burning Chamber...

    I think it's the Air itself... When Cold Air Heats Up.... Sensitive Smelling People can Smell this Smell...

    Anyway, I will post my finding once I figured it all out

    Robert

    This post was edited by rgs03833 on Sat, Jan 4, 14 at 14:37

  • coffee123
    9 years ago

    I had a similar problem...couple things that helped get rid off the smell.

    1) Don't keep the fan on (this I think was the main problem). Dust particles fall on the burners when their off, and when they turn on they burn off and causes a slight burning smell every time it turned on.
    2) Get a good filter. Doesn't need to be the most expensive and thickest but definitely not the cheapest.
    3) I placed a Ionic Pro Turbo Max air purifier in my basement, works great. Smells like there's a window open.

  • Kylee
    9 years ago

    Rgs03833 and taracol,

    Did you ever find a solution?? I just read this entire thread and have the exact same problem! I need help!! We bought our house 5 years ago brand new and I've noticed multiple times a year (usually when it gets cold or there is a change in seasons I feel like) that awful, dead animal/chemically weird smell comes through our vents I've had multiple people come out and check it and they just think Im crazy. This past year (4 years later) my husband is now able to smell the smell as well It comes and goes and is so bad it gives me a headache. With 3 little kids I'm going crazy trying to figure out what it is. If you found a solution please let me know

  • Vith
    9 years ago
    last modified: 9 years ago

    I feel the problem to the original poster is is a combination of dirty sock syndrome (as noted previously by zl700) and the heat burning off mold. What they said was the smell comes once the heat hasnt been on for a few days, then smells for the first 15 mins of it heating. I am thinking that mold had time to accumlate on your A/C coil while it wasnt heating, and when the heat turned on it burns off the mold and you get the smell. It would be nice to know if there is a constant musty smell in the summer when the A/C runs, but obviously this is an old thread and wont be answered.

    I agree with Rgs03833 that another culprit could be a blocked air return or very dirty air filter making the motor work harder than usually and causing it to burn out and release a smell.

    Also I read into that Dirty Sock Syndrome link posted above, and another idea from some discussion there is that the coils are not as good as what they used to be. They are often made with recycled aluminum some of which is from the landfill and may have an inherent stink to them. There are a lot of consumers recently that believe the coils themselves are defective and cause the smell. If anyone has a problem with DSS or other random smells you need to have that A/C coil removed and have a coated coil installed. Based on that link above, cleaning the coil is only a temporary solution to DSS. A coated coil is the permanent solution. If anyone has health problems very often such as breathing difficulty or sinus problems you are probably allergic to mold and have a problem with DSS pumping mold spores into your house.

    I am glad I read this because if I need a new coil in the future I will go with the coated coil and not take the risk in getting a stinky coil. I am highly allergic to mold and dont want to risk causing a problem with the quality of the air in my house. As mentioned above, air purifiers do help and might be a good option for a lot of people, even if you dont have DSS.

  • rabbitdog
    9 years ago

    "if I need a new coil in the future I will go
    with the coated coil"

    I think you need to be careful with a coated coil
    if it is a A-coil on top of a furnace. I
    think the coating is okay for outside coils to prevent corrosion as I think
    that is what it was originally developed to do.
    On a heat pump indoor coil it is probably okay. The temperature doesn't get as hot as in a furnace. But when they extended the application to a
    A-coil on top of a furnace I think it is in an environment that can be too hot
    for it. When it is real cold out and the
    furnace is on for a long time I suspect the coating can get too hot and begins
    to smell on its own. Now my dealer and
    manufacturer and coater can prove me wrong by removing the coil temporarily (at
    my expense I might say) but they have refused to do that because , well...maybe
    it would prove they have a problem.

  • Vith
    9 years ago
    last modified: 9 years ago

    Good to know. Did not think of that. Something to ask about / research.

  • Shannon Hillyard
    8 years ago

    This sounds about as putrid as my vents smell. I could never describe this horrible smell or at least describe it in the way that it is so nasty pungent nasty nasty. lol! I always thought it was our downstairs neighbors apartment smelling up here. I smell it whenever they have their door open. We both have two bedroom apartments but they have 9 people a dog and two cats in their apartment. There's been roaches galore outside when it's hot and they kids are always screaming at them. We have lived here for 2.5 years and have had 3 or 4 cockroaches total and always near a window. So I feel these are escapes and the roaches are quite content down there. They have one less window then us and never open up their house. We do not have central ac in the building but we do have central heat. I can't tell if this smell would be the severe infestation (which is a fact that it's in the building) or a problem in the ducts. I have always smelled it under my sinks, my fireplace and in my hallway. Now knowing more about my apartment and central heating, the hallway is where the return for the furnace is. When I open that closet it is super strong. But again I don't know if this is a leaky smell from them connecting to us. As I mentioned with all the people and animals, their dog never comes outside to go to the bathroom (we do not have yards), there are a few small children in diapers stills, and they've lived there for 13 years. Their kids are all home schooled so they are home 24-7 with it closed up all day with that many people. I know there's no way they can get the necessary upgrades that come with apartment living because they are living illegally. I struggle DAILY with keeping up the cleanliness in my own house with my two small kids. I can't imagine what it must be like to have so many over the years. And I'm a clean freak. And my house is a wreck. I have a super sensitive nose too. I always say I never lost the pregnancy nose. My fiance thinks I'm crazy about the smell but my teenage daughter gagged when I made her smell the vents and under the sink. She said she never noticed it so I made her notice it! lol!


    Sorry about that whole story but I wanted to set the stage for what I've always thought it was. The smell makes me nauseous. Our apartment is hotter than hell with the whether we've been having the past few years and living a few miles from the beach, our city doesn't usually have ac because it's only hot for a month or so out of the year. We've been in the 90's the past few years though WITH humidity. We are SoCal and usually have really great whether. Needless to say it's been a miserable first two years as a stay home mom.


    Earlier this year I tried to turn on the summer fan for our furnace to see if I could somewhat cool the house down by at least circulating our air. The smell gave me the worst headache. I've always felt headaches comes from things that are pollutant's when it is from a smell. Like tar. So now I've been leaning towards my ducts. My smell seem in the summer time. Or really whenever downstairs is closed up and it's hot. Whenever they do actually open up their house my house does not smell. My neighbor downstairs in the front house said the same thing. Are our ducts connected? Does this sound like a ventilation/furnace issue? Or does it sound like they are the external cause?



  • Shannon Hillyard
    8 years ago

    Oh and my small kids (3 and 4.5) have had horrible allergies since we moved in here. Nasty colds in the winter. This last winter both were diagnosed with asthma while sick. I started taking my son to an allergist when his mouth was breaking out like a reaction to food. His eyes are always puffy too. They tested for cockroaches and foods and the only thing that came back was a tiny reaction to red food coloring. So that food was stopped. He cleared up. They figured the eyes were pollen related and as I started regular allergy medicine his asthma is gone. Now this current heat wave he's all broken out around his mouth again. No red foods. But our house is completely closed up and we have window ac's. So obviously the furnace is not ran in the summer but it's still there and so are the ducts. Does this sound like something coming from there or is it possible for downstairs to be seeping into our apartment? I don't know how ducting works in apartment buildings so I guess that is my question as well. Or does this all sound like oddly coincidental situations? :(

  • rabbitdog
    8 years ago

    Shannon,

    It is very difficult tracking down where the smell is coming from. I might be that the ducts are just spreading it around. Could be mold, a dead animal that left bacteria around as it decomposed, almost anything. Do you have any neighbors that are from India or Nepal, or countries like those that cook with a lot of spices and onions, etc.? Could be that. It sounds like you are just renting, so my advice is to get the hell out of there if the landlord doesn't take immediate and aggressive action to fix it. Oh, and by the way, you are not crazy. You might be much more sensitive to certain smells, but that doesn't make you crazy.

  • unclebob973
    8 years ago

    After reading all of these, I think I found my problem. My furnace is electric, we bought this house new 7 years ago. The house was a Foreclosure and stunk from the day we bought it. It had sat for about 2 years. It is in Az. and we are snow-birders and only use this house in the winter months and rarely use the heater. When we get here the house always smells bad. We figure it is because the water evaporates out of the "P" traps in the toilets, sinks, Bath tubs, showers, allowing sewer gas to creep into the house. We air it out as soon as we get here with large fans, run water in all the drains, and it is fine. Turned the heater on yesterday and "holey crap" it smelled bad. Our heaters are super high efficient. The condensation from the coils goes down through a "P" trap into the sewer, this is not easy to get to, but there is a 3/4" plug that once removed, I can pour water into (with the aid of a funnel). I flushed it with R/O (reverse osmosis) water and then added some Food grade Citric acid (basically vitamin C) that we keep around to clean with instead of bleach.

    What was happening is whenever the heater fan was on, it was pulling sewer gas into the house through the P trap, because there was no water in the P trap to prevent it from doing so. (water had evaporated). My next project will be to figure out a way to put a directional valve in the drain lines. (which may be next to impossible because they are not very accessible). but if worse comes to worse, it only takes about 15 minutes to fill the P traps with water in both furnaces.

  • Kathy Hodgson
    7 years ago

    In the past few days the smell of rotten disgusting sewer is coming from my heating vents. It's getting worse and I have headaches and nausea! Never felt like this before. What should I do, or what is the problem?

  • Vith
    7 years ago

    Sewer or rotten decay is a different smell than mildew or a dirty sock smell. Sounds like as mentioned by bob (the post above you) that your condensate p-trap is dry and sewer gas is getting into your furnace. Or, dead mouse somewhere in a main supply trunk.

  • sktn77a
    7 years ago

    The internal (heating) air supply is isolated from the combustion air supply/venting and condensate drainage by the heat exchanger. There should be no sewer gas entering from the the registers. Of course, if the drain is vented into an open space (attic or crawlspace) then sewer gases could be entering the house this way (if the condensate drain goes into a sewer vent). Draining the condensate into a sewer vent is against all codes for this reason.

  • John Claudy
    7 years ago

    We once had a problem like this for our heat pump. Condensate pan drained into drain line if sink below the sink P trap. But drain line from condensate pan did not have a P trap. Added a P trap and that solved problem. Just make sure P trap from condensate pan doesn't dry out. To avoid this potential problem we added a filler port to condensate drain line, with filler opening above level of condensate pan, so we could add water to P trap.

  • Zack McKeever
    7 years ago

    Hi - a lot of these posts seem to be slightly different but thought I would share my experience in my home that may prove helpful or be similar.

    My wife and I moved to our home newly built 5 years ago tomorrow! I can't say I've noticed the smell in the first year but maybe it's poor memory. After the first year, we'd notice this propane/rotten/dead animal like smell. At first I thought the builder put something in the vents - no signs of any rodents ever and ruled this out. Next I checked the line/drain from the AC/furnace and even had a tech check and clean the pump - no help.

    plumber says there is no issue with drainage or sewer or any back up venting - ok.

    what HAS helped intermittently is calling the gas company to check the gas lines inside. I've had them 7 times in the past 2 years, each time they find a small leak - nothing major, no reading except with the sniffer right at the source of the leak. {I also have multiple CO and gas detectors on the floor (heavy gas). They have never gone off}.

    After the gas company repairs the pipe the smell is gone for a few weeks maybe months depending on warm or cold season. It comes back, gas company is back out and repeat. I have replaced two ovens in the kitchen due to them being the source of the leak. I find that the air return on the main level of my house sucks in the smell and returns it to the furnace. When the furnace kicks on we smell it out of the vents. Occasionally I can smell it in the room where the furnace is also.

    Gas company has done line checks, pressure checks, fixed leaks - I've paid them thousands to come out and fix this over and over then the smell returns - I've returned two "new" ovens due to leaks after minimal use. I have a 2 yr old son and new baby due in a month and NEED this resolved. Please let me know if you have any suggestions or have been through something similar.

  • rvgirl42
    6 years ago

    I have the same problem and I'm amazed that others do too. It's the smell of dead animal, human feces (sickly sweet), and sewer. It's horrible. It's not the AC- it's the furnace because it happens when I run both heat and cool. It gets worse when it runs consistently. It's worse in certain rooms. I've read through the posts and I'm convinced its the coil. I'm having it replaced and will post back as to whether it fixes the issue. If it does, everyone should have their answer. If you had the coil replaced, please tell me if it resolved it.

    I'm also curious to know if the drain in the floor where the furnace drips condensation could have any effect and if there is any backflow up back through the vents from there - or is it impossible?

  • mike_home
    6 years ago

    If the drain used by the furnace does not have a drain trap then it is possible sewer gas could be pulled into any nearby supply vent. Do you smell an odor from the drain itself?

  • Rose Hamilton
    6 years ago

    https://youtu.be/Ph4JheZVR0Q Just 1 ideal of problem. Didn't solve mine, but maybe someone else's

  • Jod Bronson
    4 years ago

    Does it have... Weird Sweet Smell Odor, Rotten Veggie Smell or Garlic or Cabbage Add Sweetness or Sweet Tobacco Smell.... VERY hard to described? Cause Burn Eyes, Nose, Throat or Lung Irritation or Choking Like Coughing. Headaches and Nausea - Nauseating, Pungent, Sickening, Sicken Smelly, Queasy, Respiratory Issues, On and On and On.....


    Here is the Link of the YouTube Video: https://youtu.be/jIqpBwB-jYI


    Jordan


  • Kwesi Master
    4 years ago

    rvgirl42. Hi didyou find a solution to your problem ?


  • Jod Bronson
    3 years ago

    Sorry... YOU will NEVER be able to get rid it of it.... This weird Sweet Smells. I HOLD the answer to that !!! YES, I said NEVER, that is a very bold statement. Unless I know what is causing it !!!

  • Kwesi Master
    3 years ago

    I did eventually find out what was causing I t. It’s was the vent outside the house So he So I changed it to PVC piping with a couple of elbows. No smell now

  • Jod Bronson
    3 years ago

    Sorry... YOU will NEVER be able to get rid it of it.... This weird Sweet Smells. I HOLD the answer to that !!! YES, I said NEVER, that is a very bold statement. Unless I know what is causing it !!!