Corrosion in Heat ducts: headaches, health issues

Jacqueline709

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.

pecmsg

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.

Jamie Hall

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.

mattmia2

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.

Larry Weingarten

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

HVACNUT

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?

BDR529

Old central humidifier? That'll make you feel sick to say the least.

mattmia2

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.

ethicalpaul

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.

Jacqueline709

ethicalpaul said:

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

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?

Jamie Hall said:

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

Jacqueline709 said:

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?

Jamie Hall said:

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

neilc

call your fire dept, or gas supplier,
they should come right out and take readings for CO,

Jacqueline709

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!!!

Jamie Hall

Say what? Now I'll grant you that the OSHA 8 hour limit for workers exposed potentially exposed to CO is 50 parts per million for an 8 hour day. Workers. For an 8 hour day. The ASHRAE standard for allowable spillage from vented appliances is 9 ppm. Around 10 parts per million you begin to see significant overt health effects.

35 to 40 parts per million is not normal. It's not even remotely safe for long term exposure, such as in a residence.

If I were you I'd shut that thing off, as soon as you've read this, and see if you can get someone to come out there who won't endanger your health. The symptoms which you described in your first post are more or less what you would expect from that level of CO exposure.

I'm at a loss for further coherent words here...

mattmia2

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.

pecmsg

Jacqueline709 said:

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.

Jacqueline709

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

Jacqueline709 said:

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!

PRR

Jacqueline709 said:

.....I could spray the rustoleum paint down the ducts to cover the rust,......

another thread here: "...rustoleum oil-based enamel. almost a year later
the vapor is in off-gassing are still unbearable..."
I would not use Rustoleum in the house. Maybe a tiny nick-knac but nothing large, nothing hot.

The old RustO (smelled like rotting fish oil) "never cured", which is how it kept damp off the metal for many years. OTOH it never really stopped off-gassing. (Eventually, but many-many-many years.) New RustO meets new pollution laws so will be different, but how much?

Latex paint can be violently offensive for a week but usually becomes inert. Shellac (Kilz, BIN) will make you "drunk" for a night (and set off a good CO monitor!) but hardens thoroughly.

Anyway I very much doubt metal oxides on duct surfaces are triggering your health. Not iron, not really zinc (galvanize), not even aluminum. Unless you are scraping and snorting, they mostly just stay where they formed. And you do have a strong clue about CO, monoxide, which is notoriously sickly and deadly.