Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.

Corrosion in Heat ducts: headaches, health issues

Hi all,

I've been staying in a log cabin that typically has very good air quality. It has no AC unit, and a forced-air heating system coming from a furnace. I've recently noticed that whenever I turn the heat on, I get an onset of symptoms, ranging from headaches to loss of feeling in my extremities. I am normally a sensitive person, and this is my typical reaction to mold, but seeing that this is forced dry heat, it doesn't add up to be caused by water damage. I opened some of the vents to find a ton of corrosion and rust on the metal ducts, concentrated more the farther down the duct (meaning, I don't believe it's coming from the room, because there is very little up close to the vent, and quite a lot looking down the duct). I read on a few articles that corrosion in the ducts coming from a furnace that produces dry heat can be caused by poor ventilation of the combustion gases used by the furnace to heat the air. I'm an art historian by trade, so I have no idea how any of this works, only that I feel like garbage. I read that if there is too much corrosion and the heat exchanger cracks, that can release carbon monoxide. My father, who owns the house, does not believe it is cracked, and he will check on that this weekend. So, assuming it's not cracked, what are other possibilities? Could I be reacting to the rusted metal getting blown into the air? Or could there be another issue, maybe with the gases not being vented properly? Thank you for your help.

Comments

  • pecmsg
    pecmsg Member Posts: 2,227
    edited October 2020
    1st furnaces do not produce “dry” heat. They only heat the existing air and its RH. 
    Run just the fan, do you get the same symptoms? 

    Is there a “Low Level” CO monitor in the rental? Not the standard big box store CO that’s UL approved but one that alerts at 15 PPM!

    UL Approved Monitors only alarm when the CO reaches 70 PPM for 1 hour.

    Jacqueline709mikeapolis
  • Jamie Hall
    Jamie Hall Member Posts: 16,642
    The very first thing I'd look at is the CO level in the house. This is not necessarily from a cracked heat exchanger -- although that will do it. All of the exhaust ducting from the furnace, and the chimney if there is one, must be checked and found to be absolutely sound. The exhaust termination must be properly located; if it's just a duct, far enough from windows and doors, and not where the exhaust can accumulate (such as in a corner or under a porch roof!). If it's a chimney, it must be high enough above the roof and any other obstructions. There must be adequate combustion air -- preferably from outside the structure. Tight modern structures tend to not have enough combustion air, never mind air changes per hour. This is great for energy efficiency -- but very detrimental to indoor air quality. You need enough building ventilation for two to four air changes per hour, minimum.

    Are there any exhaust fans, such as a bathroom fan or a kitchen range hood? If so, all the more reason to arrange the furnace so that combustion air comes from outside, not from in the structure.

    Than another thing to look at is the furnace itself. Assuming that it is in basically good condition, has it been cleaned recently? Has the burner been checked and properly adjusted by someone with the tools and instruments and the knowledge to use them recently? That can make a big difference.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    ethicalpaulJacqueline709
  • mattmia2
    mattmia2 Member Posts: 3,714
    Last I looked, which was a couple years ago, the big box stores had the Nighthawk with the LED display that would show lower levels if you pressed one of the buttons.

    After you have ruled out CO, definitely check for CO issues first, another issue could be the returns. They are usually constructed by enclosing various cavities of the building so a leak or even condensation in those areas could grow mold on the wood and drywall those areas are constructed from. They also typically are not well sealed so they could be pulling air from a wall cavity or sill area that they do not enclose as well.
    Jacqueline709
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,247
    Hi @Jacqueline709 , Here is a link to info on how to diagnose a cracked heat exchanger: https://www.bing.com/search?q=how+to+diagnose+cracked+heat+exchanger+in+furnace&form=QBLH&sp=-1&pq=how+to+diagnose+cracked+heat+exchanger+in+furnace&sc=1-49&qs=n&sk=&cvid=CC61CDDBC6D1442C8612B916DF246CC4
    I think I'd share this info with your dad just to make sure he checks all possibilities. CO is not something to be trifled with! There can be long term health effects.

    Yours, Larry
    Jacqueline709
  • HVACNUT
    HVACNUT Member Posts: 4,088
    edited October 2020
    Of course inspect the flue and chimney as well. There might not be a crack in the HX but flue gasses can back up if there's a blockage.
    Is the air filter clean? What type is it?
    What make and model furnace?
    Jacqueline709
  • BDR529
    BDR529 Member Posts: 196
    Old central humidifier? That'll make you feel sick to say the least.
  • mattmia2
    mattmia2 Member Posts: 3,714
    HVACNUT said:

    Of course inspect the flue and chimney as well. There might not be a crack in the HX but flue gasses can back up if there's a blockage.
    Is the air filter clean? What type is it?
    What make and model furnace?

    Or some fundamental design or setup flaw that caused it to never draft right in the first place.
    Jacqueline709
  • ethicalpaul
    ethicalpaul Member Posts: 3,089
    My father, who owns the house, does not believe it is cracked

    Unless he's an HVAC technician by trade, this scares the heck out of me.
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
    Jacqueline709STEVEusaPA
  • Jacqueline709
    Jacqueline709 Member Posts: 9

    My father, who owns the house, does not believe it is cracked

    Unless he's an HVAC technician by trade, this scares the heck out of me.
    He was, 35 years ago... Not anymore, and definitely not up to date on standard practices. He hasn't even checked on it in years, so it scares and infuriates me too.
  • Jacqueline709
    Jacqueline709 Member Posts: 9
    pecmsg said:

    1st furnaces do not produce “dry” heat. They only heat the existing air and its RH. 

    Run just the fan, do you get the same symptoms? 

    Is there a “Low Level” CO monitor in the rental? Not the standard big box store CO that’s UL approved but one that alerts at 15 PPM!

    UL Approved Monitors only alarm when the CO reaches 70 PPM for 1 hour.

    Thanks for this resource. I looked up the Kidde alarm we have, which seems to sound at 50ppm. So that's not really helpful, especially because I refuse to run the heat for hours just to see if it will make the alarm go off, at the expense of my health. Can i pick up a more sensitive one at the Home Depot?



    Than another thing to look at is the furnace itself. Assuming that it is in basically good condition, has it been cleaned recently? Has the burner been checked and properly adjusted by someone with the tools and instruments and the knowledge to use them recently? That can make a big difference.

    Thank you for all this information. I can imagine the furnace has NOT been cleaned recently. I went down there to look at some stuff and felt really sick afterwards.
  • pecmsg
    pecmsg Member Posts: 2,227

    pecmsg said:

    1st furnaces do not produce “dry” heat. They only heat the existing air and its RH. 

    Run just the fan, do you get the same symptoms? 

    Is there a “Low Level” CO monitor in the rental? Not the standard big box store CO that’s UL approved but one that alerts at 15 PPM!

    UL Approved Monitors only alarm when the CO reaches 70 PPM for 1 hour.

    Thanks for this resource. I looked up the Kidde alarm we have, which seems to sound at 50ppm. So that's not really helpful, especially because I refuse to run the heat for hours just to see if it will make the alarm go off, at the expense of my health. Can i pick up a more sensitive one at the Home Depot?



    Than another thing to look at is the furnace itself. Assuming that it is in basically good condition, has it been cleaned recently? Has the burner been checked and properly adjusted by someone with the tools and instruments and the knowledge to use them recently? That can make a big difference.

    Thank you for all this information. I can imagine the furnace has NOT been cleaned recently. I went down there to look at some stuff and felt really sick afterwards.
    Search the Web for "Low Level CO Monitors"
    Defender is the model I recommend
    Jacqueline709mikeapolis
  • neilc
    neilc Member Posts: 1,347
    call your fire dept, or gas supplier,
    they should come right out and take readings for CO,
    mikeapolis
  • Jacqueline709
    Jacqueline709 Member Posts: 9
    Hi everyone!! BIG UPDATE

    I had the heating company come to the house and do a full inspection. They checked everything, including CO levels. They said in the basement it's about 35-40ppm, which they considered normal. I'm not sure what you guys think of that level, any recommendations on how to lower it are appreciated. They found no cracks or issues with the Heat Exchanger. BUT, they did find that the ignition was delayed, so oil was shooting past the high voltage bars (sorry, I forget what these things are called) and excess oil was collecting on the other side and then turning into fumes that could come up into the house. This was problem #1. Another problem was that they said I need to change the filter on the furnace. My father had assumed that the filter would be changed with each yearly inspection from the energy company; alas, the company does not carry new furnace filters; this was the original filter from 26 YEARS AGO when the house was built. Oy, vey. They pulled it out and the dust on it was about the thickness of a carpet. Gross. They gave me the dimensions and told me to go get a new one at Home Depot, which I did. They agreed that I could spray the rustoleum paint down the ducts to cover the rust, and agreed with my comment that maybe the corrosion process would slow down if the filter on the furnace was regularly replaced. I am hoping and assuming my health issues will improve now with the new filter and the fixed ignition. Let me know your thoughts!! Thanks again for everyone's help!!! <3<3<3
  • mattmia2
    mattmia2 Member Posts: 3,714
    Don't spray paint in the ducts, that will emit some fumes for a while especially with the heat from the furnace.

    Get a CO detector. I installed a vented rage hood after briefly seeing about 15ppm while boiling 2 large pots of water. What you are seeing is not normal, it isn't even normal directly in the exhaust much less in the ambient air.
    ethicalpaul
  • pecmsg
    pecmsg Member Posts: 2,227
    edited October 2020

    Hi everyone!! BIG UPDATE
    They said in the basement it's about 35-40ppm, which they considered normal. I'm not sure what you guys think of that level,

    Tell them you want that in Writing!

    Contact your local Fire Department and ask them what they think of that statement.
    mattmia2rick in Alaska
  • Jacqueline709
    Jacqueline709 Member Posts: 9
    Hi everyone,

    Thank you for all of this information. I found it a bit suspicious as well. So far, I'm feeling a bit better since the filter was changed, but I think I will go forward with presenting the CO results to the fire department and asking if this is normal. All the levels are listed on the receipts for the tests done.
  • pecmsg
    pecmsg Member Posts: 2,227

    Hi everyone,

    Thank you for all of this information. I found it a bit suspicious as well. So far, I'm feeling a bit better since the filter was changed, but I think I will go forward with presenting the CO results to the fire department and asking if this is normal. All the levels are listed on the receipts for the tests done.

    From National Comfort Institute. Leaders in Combustion Analyses and CO Exposure
    https://www.myhomecomfort.org/carbon-monoxide-levels-risks/

    Done wait to make the call!