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Carbon Dioxide poisoning symptoms
• At 1% concentration of carbon dioxide CO2 (10,000 parts per million or ppm) and under continuous exposure at that level, such as in an auditorium filled with occupants and poor fresh air ventilation, some occupants are likely to feel drowsy.
• The concentration of carbon dioxide must be over about 2% (20,000 ppm) before most people are aware of its presence unless the odor of an associated material (auto exhaust or fermenting yeast, for instance) is present at lower concentrations.
• Above 2%, carbon dioxide may cause a feeling of heaviness in the chest and/or more frequent and deeper respirations.
• If exposure continues at that level for several hours, minimal "acidosis" (an acid condition of the blood) may occur but more frequently is absent.
• Breathing rate doubles at 3% CO2 and is four times the normal rate at 5% CO2.
• Toxic levels of carbon dioxide: at levels above 5%, concentration CO2 is directly toxic. [At lower levels we may be seeing effects of a reduction in the relative amount of oxygen rather than direct toxicity of CO2.]
Symptoms of high or prolonged exposure to carbon dioxide include headache, increased heart rate, dizziness, fatigue, rapid breathing, visual and hearing dysfunctions. Exposure to higher levels may cause unconsciousness or death within minutes of exposure.
Distinguishing between high carbon dioxide levels CO2 and low oxygen levels O2 in air
What may be unclear in some cases is whether the sub-acute (sub-toxic) effects at modestly-elevated levels of CO2 in air stem from more from exposure to higher levels of carbon dioxide or whether they are due to reduced levels of oxygen. In an enclosed space such as a tight home or an enclosed basement or work space, increasing the level of CO2 is likely to simultaneously reduce the proportion of Oxygen (O2) in that same breathing air.
Some experts opine that a complaints that seem to be associated with high CO2 problem in many if not most circumstances are likely to be actually due to the corresponding reduction in available oxygen in air rather than high toxicity levels of CO2 in the air. As carbon dioxide levels climb above a few percent the relative proportions of gases making up that air change: the concentration of oxygen in the air inhaled is reduced as the amount of CO2 is increased.
More carbon dioxide may mean less oxygen: Let's say, sake of simplicity, that we're converting oxygen to carbon dioxide in an enclosed space. Then when the CO2 level has increased from its normal amount in air (about 0.03%) up to a higher concentration in air of 1.4% CO2 the concentration of oxygen in air will have decreased from 20.9 to 19.5%. Reducing the oxygen concentration from 20.9% down to 19.5% is equal to a 6.7% reduction in the oxygen level.
What are the effects on humans (and other animals) of reduction of the oxygen levels in air? At sea level, breathing air in which the O2 level has fallen to 16% percent is equivalent to being at the top of a 9,200-foot mountain - close to the level at which many people will experience shortness of breath while walking. 12% Oxygen in air at sea level corresponds to breathing normal air at an elevation of about 17,400 feet.
CO2 HEALTH EFFECTS - Potential Health Hazards of Toxic Gas Exposure
Hazard evaluation consists of comparing measurements of exposure (or dose) with exposures (doses) known to be safe or known to be hazardous. For the most part, because of biological variation, "no effect" levels are much easier to estimate than are "first effect" or other levels indicative of injury.
Toxic levels of carbon dioxide: According to occupational exposure and controlled atmosphere research into CO2 toxicology, CO2 is hazardous via direct toxicity at levels above 5%, concentrations not encountered in nature [except perhaps at or near an active volcano or at water-logged soils]. At these high levels there is risk of death from carbon dioxide poisoning. At lower levels there may health effects and there certainly are complaints of exposure at lower levels.
On specific individuals, the effects of exposure to elevated levels of carbon dioxide (CO2) vary by individual and with exposure level, and exposure duration, ranging from drowsiness (perhaps at levels over 1000 ppm continuous exposure) to the toxic effects listed just above.
How might CO2 accumulate at a dangerous level in a residential property?
Carbon dioxide, CO2, from a small leak is unlikely to be dangerous, as it can be expected to be diluted with fresh air mixing in a building. But there can be exceptions in which carbon dioxide may accumulate and reach higher, even dangerous concentrations indoors.
• Flue gas spillage: in an enclosed gas-fired boiler room with a deficient chimney draft can produce high levels of CO2. In a case in which there is sufficient combustion air, say from a direct air duct to the gas burner, the system may not be producing more dangerous carbon monoxide (CO), but the heating system may nonetheless spilling flue gases with a high level of CO2 into the room from a defective chimney. Since CO2 being denser than air it may accumulate in an enclosed basement, crawl space, or boiler room. Alternatively, because the CO2 in this case is a heating system exhaust, it may be warmer than surrounding air and it may rise upwards in the building into the living space. For this reason when we measure for the presence of flue gases, even if the gas is one which is "supposed to be" heavier than air, we may measure both high and low in the test area.
• Soil sources of high carbon dioxide in buildings: NIOSH reports on an investigation of complaints by homeowners of blurred vision, breathlessness, and "episodic mild confusion" caused by exposure to from elevated carbon dioxide levels in a finished basement and an adjacent crawlspace. West Virginia Department of Environmental Protection detected carbon dioxide levels up to 9.5 percent in the basement and CO2levels up to 11 percent in the crawlspace grave, with 12 percent in the basement floor drain (suggesting a soil source of CO2 in a home in West Virginia home, according to a NIOSH report. CO2 levels in the soil surrounding the home were measured at levels up to 8 percent. The probable source of the high CO2 levels in the soils under and around this home was probably due to [coal] mining activities.
Are the effects of breathing CO2 permanent?
Any detrimental effects of low-level CO2 exposure are reversible, including the long-term metabolic compensation required by chronic exposure to 3% CO2. -- "A Review of Human Health and Ecological Risks due to CO2 Exposure," American Geophysical Union, Spring Meeting 2001, abstract #H31C-13, Hepple, R. P.; Benson, S. M., 05/2001.
CO2 EXPOSURE LIMITS - Carbon dioxide exposure limits PEL and TLV set by OSHA and NIOSH
Carbon dioxide is regulated for diverse purposes but not as a toxic substance.
• The U.S. EPA CO2 exposure limits: The U.S. EPA recommends a maximum concentration of Carbon dioxide CO2 of 1000 ppm (0.1%) for continuous exposure.
• ASHRAE standard 62-1989 recommends an indoor air ventilation standard of 20 cfm per person of outdoor air or a CO2 level which is below 1000ppm.
• NIOSH CO2 exposure limits: NIOSH recommends a maximum concentration of carbon dioxide of 10,000 ppm or 1% (for the workplace, for a 10-hr work shift with a ceiling of 3.0% or 30,000 ppm for any 10-minute period). These are the highest threshold limit value (TLV) and permissible exposure limit (PEL) assigned to any material.
• OSHA CO2 exposure limits: OSHA recommends a lowest oxygen concentration of 19.5% in the work place for a full work-shift exposure. As we calculated above, for the indoor workplace oxygen level to reach 19.5% (down from its normal 20.9% oxygen level in outdoor air) by displacement of oxygen by CO2, that is, to reduce the oxygen level by about 6%, the CO2 or carbon dioxide level would have to increase to about 1.4% 14,000 ppm.
In summary, OSHA, NIOSH, and ACGIH occupational exposure standards are 0.5% CO2 (5,000 ppm) averaged over a 40 hour week, 3% (3,000 ppm) average for a short-term (15 minute) exposure [we discuss and define "short term exposure limits" STEL below], and 4% (40,000 ppm) as the maximum instantaneous limit considered immediately dangerous to life and health. All three of these exposure limit conditions must be satisfied, always and together.
What laws regulate carbon dioxide exposure levels?
Of the several industrial hygiene standards-setting groups in this country, the most important and/or most quoted are the National Institute for Occupational Safety and Health (NIOSH), the Occupational Safety and Health Administration (OSHA), and the American Conference of Governmental Industrial Hygienists (ACGIH) but these are recommended standards, not laws.
Standards promulgated by OSHA (called Permissible Exposure Limits or PELs) have the force of law. The other standards are advisory. However OSHA claims the power to force compliance with NIOSH "Recommended Standards" if it chooses to do so. (The main advantage of ACGIH Threshold Limit Values (TLVs) is that they are reviewed and updated annually; neither NIOSH nor OSHA updates its standards with any regular frequency.)
NIOSH limits on Carbon Dioxide Exposure: NIOSH's recommended CO2 exposure limit for 15 minutes is 3 percent. A CO2 level of 4 percent is designated by NIOSH as immediately dangerous to life or health.
OSHA limits on Carbon Dioxide Exposure: The U.S. Department of Labor Occupational Safety & Health Administration, OSHA, has set Permissible Exposure Limits for Carbon Dioxide in workplace atmospheres at 10,000 ppm of CO2 measured as a Time Weighted Average (TWA) level of exposure and OSHA has set 30,000 ppm of CO2 as a Short-Term Exposure Limit (STEL). OSHA has also set a Transitional Limit of 5,000 ppm CO2 exposure TWA. [OSHA's former limit for carbon dioxide was 5000 ppm as an 8-hour TWA.]
Definitions of Short Term Exposure Limits or STEL
What is the definition of "short term exposure" or "Short-Term Exposure Limit (STEL)"? The ACGIH has defined STEL as the concentration (in this case of a gas in air) to which workers can be exposed continuously for a short period of time without suffering from irritation, chronic or irreversible tissue damage, or narcosis of sufficient degree to increase the likelihood of accidental injury, impair self-rescue or materially reduce work efficiency.
What is a "short period"? And what is "short term exposure"? The definition of "short period" is provided indirectly by ACGIH:
1. If during an 8-hour work shift (and before it has ended) a worker is exposed to a substance in excess of the threshold limit value, time weighted average exposure permitted exposure level for the entire shift, then that exposure has exceeded the short term exposure limit or STEL.
2. If a worker is exposed to more than four STEL periods during the course of an 8-hour work shift, with less than 60 minutes between those exposure periods, then also that exposure has exceeded the STEL.
How to use gas detection tubes for measuring the level of various gases
The colorimetric gas detection tubes, here showing a tube made by Dragger, are a relatively inexpensive way to test for the level of specific gases. The tubes are quite accurate and can be selected and used down to very low concentrations of various gases, provided that a properly chosen and calibrated gas testing pump is used. In some cases for very precise measurements a correction factor needs to be applied for temperature at the time of measurement. We use Dragger tubes as well as another system of tubes and pump made for and sold through Gastec for testing indoor levels of specific gases.
What are the component gases that make up normal air and in what proportions or percentages do they occur?
At sea level on earth, what is the composition of the air we breathe? That is, what gases make up normal outdoor air? How much CO2 is in air? How much oxygen is in air? and how much nitrogen is in the earth's atmosphere? Here is the mix of gases in normal outdoor air. The earth's atmosphere (measured close to ground level) is made up of 78.1% nitrogen, 20.9% oxygen, 0.9% argon, 0.03% carbon dioxide, and 0.04% other gases. Let's look at some typical CO2 levels in both percentage and expressed in parts per million, which is how most instruments measure gas concentrations. [The mix of gases in air near some manufacturing facilities or in some cities may be a bit different.]
What are typical Carbon Dioxide levels in air?
• Carbon dioxide CO2 levels outdoors near ground level are typically 300 ppm to 350 ppm or 0.03% to 0.035% in concentration.
• Carbon dioxide CO2 levels indoors in occupied buildings are typically around 600 ppm to 800 ppm or 0.06% to 0.08% in concentration. You'll find this data in many indoor air quality articles and books and it's consistent with what we find typically in our own field measurements.
• Carbon dioxide CO2 levels indoors in an inadequately vented space with heavy occupation is often measured around 1000 ppm or 0.10% in concentration. I have measured levels around 1200 ppm in occupied basement offices in a hospital where the staff worked in an area which had no decent fresh air intake into their ventilation system. In 1989 I also measured 1200 ppm at chest height in the center of the sanctuary in a Jewish synagogue during the high holy days in a small New York city. I also observed people nodding off. We were never sure if it was a droning sermon, exhausted worshipers at the end of a long week, or the CO2 level. But there was no doubt that we were not meeting recommended ventilation standards for that space.
• Carbon dioxide levels above 1500 to 2000 ppm are likely to be reached only in unusual circumstances (being enclosed in an airtight closet for a long time) or in industrial workplace settings such as we cited above. |
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Ticking Noise Elimination Page
It has been more then seven years since I have discovered the way how to fight the ticking noise problem including four years since I have started helping people on the web. So now, it was time when I put all my experience together on the one webpage. On this new page you can find out:
- How to find a source of the ticking noise in your basement and how to quiet it down once and for all
- How to cut the drywall if a source of the noise is behind it and how to fix it when it’s done
- What to do if the ticking noise coming from the wall and how to eliminate it without the drywall cut
- What to do if your ductwork making ticking noise in the attic
- How to eliminate the ticking noise if it is coming from PVC or copper pipes inside, and PVC concentric on the outside of your house
Price for the instant access to the page is only $8.50! Just use the “Buy Now” button below.
Instant Access:
After you have purchased a paid page; PayPal is going to bring you back to my website. In order to see the paid page you have to click on the “Register” button, fill out the form, choose your own Username and Password and click on the “Register” button at the bottom of the form – congratulation, you are on the page you are paid for!
Important: After you have purchased any Paid page or Download page and PayPal brought you back to my website, the first thing that you should do is to save that page in your Favorites. Then if something went wrong you always can come back to reregister yourself on my website again.
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Noisy ducts – they are almost in every house, but most of the people just use to it or were misled by their Builders. I've decided to conduct a search and find out what people are able to find on the web for this topic. I've tried Google and Yahoo for about four hours and you can see here what I’ve found:
 Bunch of the builders sites such as:
www.goodier.com, www.beagleproductions.com, www.derekalan.com
indicate the problem this way:
Ductwork Noise:
When your metal ductwork is heated it will expand and when it cools it will contract. Some popping or pinging sounds are the natural result of ductwork heating and cooling in response to air flow as the system operates.
 That’s it, they are done, and the problem doesn’t exist anymore! So, its looks like they show us a big, thick, probably, with a couple of calluses Builder's finger, every grown-up in this country knows what it is for.
Here is another builder showing us the same attitude:
www.pulte.com:
VIBRATION FROM HEATING OR COOLING EQUIPMENT
It is normal for heating/air-conditioning equipment to generate some noise and vibration. Under THE WARRANTY, no corrective action is required.
As you can see they are simple covering their butts with meaningless bureaucratic slur!
The others are taking more informative approach:
www.askthebuilder.com
DEAR TIM: Our new home is now three years old. Ever since move-in day there have been annoying ticking noises in several interior walls of our home. Some of the noises start minutes after our furnace comes on. The clicks then go away five minutes after the furnace shuts off. We also have cracking noises when someone takes a bath or shower in a second floor bathroom. The builder says all of this is normal and nothing can be done. We never had this problem before. What is going on and what can be done to stop these very annoying noises? Donna A. Columbus, OH
 DEAR DONNA: You are a victim of simple expansion and contraction. The ticking, clicking and cracking noises are a by-product of metal ducting and pipes and plastic drain lines that are rubbing against the wood framing members of your home. These pipes and ducts grow in size as they are heated by the warm air and water that passes through them. The expansion is a perfectly normal thing to happen, but the associated noise is not supposed to happen……
Exorcizing these demons from your walls is not going to be easy. You will need to isolate and identify the exact trouble areas. Doing this almost always involves removal of the drywall or plaster. You can then often clearly hear and see the location where a pipe or duct might be rubbing against a wood framing member. The contact zone will need to be enlarged if possible so that an air gap exists for the pipe or duct to freely move. Do not start to cut away wood or enlarge holes in joists or studs. There are strict limits to the notches and holes that can be made in framing members. You can compromise the structural integrity of your home if you take away necessary wood. If in doubt, contact your local building inspector. Many inspection agencies will gladly advise you on what you can and can't cut. They do not want you or a family member to become a statistic.
Don't count on lubricants to always solve the problem. They may be a short-term fix but over time the lubricant may dissipate. Permanent noise solution comes when you isolate the pipes and ducts from the wood framing.
Great builders and craftsmen also account for lumber shrinkage. The lumber used to frame the house can actually shrink over time. Openings that were fine during the construction phase may become tight only 6 months later. There is no substitute for experience and brains when it comes to small detail items such as this.
 So Tim actually didn't help her too much, did he? At first he suggested to enlarge the contact zone, but after that said: don’t start to cut away wood… so, what she supposes to do? To cut, or not to cut? – Something Shakespearean is in this question! It’s seems to me that Shakespeare could help better.
If Donna would be found the way to my website I would help her just for $8.50 with a solution which is really works! |
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www.improvenet.com
Q.When my furnace kicks on, I hear all kinds of clicks and clacks and booms in the ducts. What's the problem?
A.Your noisy ducts could be caused by a number of things. One of the most common problems is undersized ductwork, which causes the ducts on the supply side to expand as they pressurize. This in turn creates a small vacuum on the return side. In both cases, the ducts will expand and contract. When the blower comes on, the tin ducts begin making a banging sound. When the plenum causes banging noises, it normally means the return air part of your heating system is starving for air. Every warm air furnace manufacturer will give you a temperature rise number they expect to see from their unit. Check your unit by taking a temperature reading of the return air and supply air. The findings should match the manufacturer's requirements. If the temperature is too high, you do not have enough return air. This condition will shorten the life of the furnace.
 On this website a guy was saying: “When the plenum causes banging noises, it normally means the return air part of your heating system is starving for air.” – But now what? What is he suggested to do? But look to the left of; I hope you are mature enough to find the right answer!
www.doityourself.com
Q. This is a good one. I can hear a "ticking" sound comeing from somewhere in the ductwork of my central heating system (heat pump). The ticking sound seems to be located on one specific area of the house. I almost sound like water dripping on the metal, but I don't see any signs of dripping water or rust. The sound can be heard when the heat is not running. The ticking is fairly constant in most cases, sometimes it sounds very fast an others a longer interval between ticks. I can go down into my basement with some of the ductwork is exposed. If I push up on the area where the sound is, it goes away for a short time but eventually comes back. I don't know what this is and it is driving me nuts. Any suggestions on what to look for would be appreciated!
 A. Hey guy this is PDF.A quick,inexpensive remedy might be a flex collar.If your duct work comes straight off the supply and is solid all the way to your diffusers....you can purchase a flex collar.It's just a piece of sheet metal wrapping that has a canvas or rubber coupling between it.It can be bought by the foot.This may help with expansion and contraction.A sheet metal shop in your area will have it in stock.To install you will need a pair of snips,a drill and some self tapping sheet metal screws.PLEASE wear gloves!!Sheet metal has a way of slicing and dicing the fingers and hands.PDF.
This explanation is just wonderful, you just have to buy a couple of boxes of flex collars, canvas and redo the entire system of ductwork. If your life is boring or you are just on a verge of depression and decided to begin all over again it would be a nice start! But not to mention that this recommendations won’t work anyway. Don’t trust me try it for yourself! But PLEASE wear gloves!!
www.thisoldhouse.com – Actually this website isn’t bad at all. If you are planning some kind of remodeling project or just a minor repair go there. They even have there own videos, it’s what I'm planning to have in a near future.
But for this particular question there are still no answers in sight:
Q: The metal ductwork in the ceiling of our finished basement pops and bangs every time the furnace comes on in the winter, then makes more noise after the furnace shuts off. Is there anything we can do to stop the banging?
A: Richard Trethewey replies:
Metal ducts make all sorts of noises. In some cases, excessive air flow can cause whistling. Sometimes, pressure differences between the supply and return ducts can move their walls in and out, resulting in a rumbling sound called "oil-canning." And ductwork can carry the sound of a noisy blower all over the house. But I suspect your problem is caused by hot air rushing into a cold duct, which makes the metal expand. You might hear some innocuous creaking, but if the duct is rubbing against wood, it might suddenly "pop" and reverberate, then pop again as the metal cools.
 What can you do? Short of covering all your ducts with fiberglass insulation, or opening them up and inserting acoustic duct liners , the best you can hope for is a modest reduction in the noise. Use rubber pads to isolate ducts from wood. Make sure there's nothing blocking the air register at the return, which can lead to pressure problems. Have an HVAC technician check the system to make sure it's not pushing more air than it was designed for. And if your furnace doesn't already have a flexible transition to isolate furnace noises, ask the technician to install one.
“ Short of covering all your ducts with fiberglass insulation” – who can explain what that means?
If he is suggesting wrapping the duct with insulation, but it’s a big and difficult job and it doesn’t solve the problem at all.
 “or opening them up and inserting acoustic duct liners” – I’m holding my breath...... opening what up...... ductwork!!! I probably lost my understanding of the English words!
This guy possibly has bolted from a kitchen. There you can easily open up a turkey and insert wherever you want: stuffing or an acoustic duct liners it’s just depends on what you are smoking!
I know it is funny, but some of the visitors of my website seriously mulling the idea of “inserting acoustic duct liners”! Folks, it is almost impossible to do! In order to do that you have to disassemble your entire ductwork system, take the ductwork apart, glue and staple with special pins acoustic duct liner to the duct’s halves, put ductwork back together, suspend and assemble the entire system back on!
Furthermore, some ductwork is extremely difficult to take apart, so you have to pry the seam open with the flat-tip screwdriver! After that, the seam will be pretty much destroyed and if even you will try to hammer it down it won’t hold duct halves in tact, so you have to screw them back together!
In addition, when this entire incredibly stupid and difficult job will be done it won’t eliminate the ticking (pinging) noises!
 Therefore, the only benefit you are going to have after this job is done
you may consider yourself as a professional ductwork installer and
start looking for a job in this field! However, here is my advice: do not tell
this story while on the interview, the interviewer may consider you are
an idiot and will never give you a job offer!
 
Yes, it is not a joke! I found these pictures on the web… This guy was doing DIY home theater project and he did not invent anything better but insulated a duct with an acoustic duct liner!
 
He bought some adhesive, pins and glued the duct from inside! I have no idea how he managed to do that, but he can be proud of himself, because he is definitely earned a bed in one of the mental institutions in this country.
Here is the most recent question about ticking noise which I found on the gardenweb.com:
Question:
We just replaced our 28 year old high efficiency gas furnance with a new high efficiency gas furnace. Furnace is extremely quiet, nice, service was great but it is causing a continous ticking/popping noise in the metal duct work right by the furnance about 3 seconds apart. We can occassionally here popping and ticking elsewhere but it's the loudest here. It seems when the fan runs continously it is more noticeable. In the evening it seems more noticeable too (maybe it's just more quiet). It's been 2 weeks now and we have seriously not slept. We are living in a 60s ranch and the furnace is right under our bedroom.
I understand metal heats and contracts. I told the furnace guys that maybe the heat coming out of the furnance is too hot (I read this on another website forum). They said they've only seen that happen when it's an old furnace - nowadays the airs not hot like that and it's different technology.
Could we have been sold the wrong furnance for our house? I mean why would the old one not do this and the new one does? I know now they have to put a vent to outside a pipe so maybe the heating and cooling feature causes more metal to expand contract but... it's not like we are going to get new ductwork...
What do we do?
I’m pretty sure this guy have visited my website, because it’s on the first or second pages of every search, but for unknown reason he decided to find help some place else:
 Answer:
Couple of things:
-Is the furnace the correct size?
-It could very well be contracting of metal ducts. You could try having them insulate the supply plenum – insulation of the plenum has nothing to do with the noise elimination!)--or maybe just reinstalling the small supply plenum portion (which, if it's in bad condition, really should have been included in a complete, professional installation).
Possible causes for your problem,
Furnace oversized (let's hope not) – it’s can’t be a cause of the problem!
Blower speed set too high (easy to fix) – it’s also have nothing to do with the problem!
discharge temp too high (when the installers told you they had not seen that with this "new technology did they have a temperature sensor in their hand)
some foriegn matter in the ductwork like a loose piece of metal, tape or insulation(this is most likely your problem as you say you hear it with the fan on. – Loose piece of metal can’t make the ticking noise – period!
Here is how website: www.ehow.com taking a shot to the ticking noise issue:
If you're heating duct is making noise, it's a matter of expansion and contraction. – This is true! The ducting and pipes are rubbing up against the wood framing members in your walls. When warm air passes through ducts and pipes, they expand. Suddenly, they're rubbing against the wood frame, creating the annoying noise. The only way to eliminate the noise is to isolate the ducts and pipes from the wood framing. – This is true again!!
Step1
Figure out exactly where the heating duct noise is coming from. To identify the problem area, remove the plaster or drywall, and then listen for the heating duct noise. Look along the duct or pipe to see where it's rubbing against your home's wood framing. – Good boy!!
Step2
Enlarge the spot where the ducts or pipes come into contact with the framing. You want an air gap to exist so that the heating duct or pipe can move freely. – Enlarge? But how? If you will try to cut framing you may cut a duct or copper pipe!
Step3
To avoid threats to the structure of your home, don't bore bigger holes in the studs or joists and don't cut away the wood. – Well, well, well here we again! This dude probably read Tim’s advise above!
Step4
Use a lubricant to ease the problem. This probably is a temporary fix because the lubricant may dissipate over time. – This is true, lubricant will be absorbed by wood over time!
Step5
Hire a heating contractor to insert flexible insulation ductwork between the furnace and the ducts if what you're hearing is a pinging, metallic sound. – This one won’t work at all, but this one lies in the main goal of that website: just give you a hint how to resolve your problem and send you to a heating contractor as soon as possible! Don't believe me check it out for yourself!
Here is one more thread from the Forum website:
BigSwede
Ductwork Banging/Popping
My ductwork has an issue where it makes a banging or popping noise when it expands or contracts. It’s not coming from the furnace but definitely the ducts. I have a two-storey home with a finished basement that is 7 years old. I have owned the house for 2 years and have had this issue the whole time. The previous owners said they had an HVAC guy look at the issue but were told that it isn't causing any damage so just live with it. – Sounds familiar!
It seems to happen in the 1st level floor joists ( basement ceiling ). I have popped off some of the drop ceiling tiles and noticed that the ductwork sits on 2"x2" wooded crossers between the floor joists. Is this proper? I'm thinking that the expansion or contraction of my ducts resting on the wood reverberates through the floor joists making the rather loud banging noise.
Just to isolate the issue to ductwork, there are no cracks in my walls to indicate shifting foundation. Plus, I've noticed that when I raise or lower the temp the bangs become more frequent and when I keep the temp constant I may get one or two bangs per day.
Has anyone ever run into this problem before? Any suggestions would be greatly appreciated. – Well, I am runing through this problem almost on a dayly basis, why you did not ask me for help?
 airman.1994
The contractor that installed the duct went the cheap way! Most do! They did not cross break the metal or they did not use a heavy enough gauge. You could take some thicker metal and screw it to the bottom of the duct to help it be more ridged. – No comments so far, just read and injoy!
BigSwede
Thanks for the reply. You say to screw thicker metal to the bottom of the duct. These are 5" circular metallic ducts. How exactly should I go about screwing the metal to the ducts? - OK, I hope you got it! Airman probably so drunk he even does not understand what is going on!
Also, what do you mean by "cross break the metal"? I've also heard that ducts should be supported by hangers whereas mine are supported by wooden crossers between the floor joists. Should I look into hangers or just leave them the way they are?
This is funny, but it is not over yet! Airman. 1994 keeps posting nonsense, but BigSwede keeps pushing him:
Airman. 1994
So all you have is round duct and no square? – How this moron came to this conclusion?
If that is the case you will have to replace the round pipe. – Replace the round pipe? This becomes really insane!
The wood is OK! Not the best but OK. – No, it is not!
Id say if the trash installer cut these corners what else did he do. I would have a good HVAC company come out and take a look at the system. Might save you lots of money in the long run. – Might save money on what?
BigSwede
I thought that round ductwork is normal. The main duct coming from the furnace is square but the duct pipes that branch off the main duct are round. These are the pipes that are sitting on wood and seem to be making the popping noise. Is there anything that can be done to the round ductwork to reduce popping? Thanks again.
Airman. 1994
Never heard round pipe pop! – Of course, only beer pops sometimes!
Must be very light gauge. How about running a screw from the wood into the duct. – This is an interesting idea! Run a screw through 2”x 2” wood it’s the best way to crack it
BigSwede
I may give that a try. It may be coming from the main square duct but I'm almost positive its the circular ducts making the noise. When you talk about cross breaking the ducts, what do you mean? Also the part about screwing more solid metal to the bottom, do mean to screw a sheet of metal or a rod? Thanks. – Questions, questions, more and more questions…
 furd
I agree with airman, snap, crackle and pop of round duct just doesn't happen. Unfortunately it IS common with light-gauge rectangular duct. – "I agggreee withth air-airmannn"- Another “pro” just emerged, probably from the same pub!
What airman means by the term "cross breaking" (or braking) is that when the duct is bent up from a flat sheet of metal the brake (bending machine) is used to put slight creases in an X pattern across the wider section of the duct. It adds tremendous stiffness and prevents (in almost all cases) the duct from doing the snap, crackle and pop from changes in temperature and internal air pressure.
BigSwede
Most of my rectangular ducts are inaccessable as they are in bulkheads. Some I may be able to access the tops only. Are there any ideas on how to minimize this situation or possibly fix it?
That is it, no more follow-ups. Does it worth saved $8.49? You decide!
To sum up: I really tried hard and I wasn’t capable of finding any good advice for this particular problem. I understand it’s difficult to spend even $8.50 when you are not sure about a result. However, you have four choices:
1. Live with the noisy ductwork for the rest of your life and hope that one day you will use to it or sell the house!
2. Get all the information for free from the web, but don’t waste your time look above: I already wasted it for you.
3. Hire a heating contractor, spend hundreds of dollars and at least you will find who to blame!
4. Pay $8.50 and get the real solution!
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