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Toxicity of Carbon Monoxide Gas Exposure, Carbon Monoxide CO Poisoning Symptoms, Carbon Monoxide Exposure Limits, and Links to Toxic Gas Testing Procedures
IF YOU SUSPECT CARBON MONOXIDE POISONING GO INTO FRESH AIR IMMEDIATELY and get others out of the building, then call your fire department or emergency services for help.
CO POISONING SYMPTOMS - Carbon Monoxide Poisoning Symptoms
Carbon monoxide characteristics
Carbon monoxide (CO) is a colorless, odorless, tasteless gas that, physiologically, is a chemical asphyxiate. When inhaled, it combines with hemoglobin more readily than does oxygen, displacing oxygen from hemoglobin and thereby interfering with oxygen transport by the blood. In other words, breathing carbon monoxide can lead to asphyxiation - unconsciousness and even death.
A person suffering from carbon monoxide (CO) intoxication may have these symptoms:
1. first experience euphoria (similar to the effect of a martini or two)
2. then headache
3. and possibly vomiting as the concentration of carboxyhemoglobin in the blood increases.
Other symptoms of Carbon Monoxide
• Weakness
• dizziness
• Lethargy
• Confusion
In addition to neurological effects, heart damage has also often been reported in CO or carbon monoxide poisoning cases - see comments below.
Safety Suggestions: Install Carbon Monoxide Detectors in addition to Smoke Detectors
Carbon monoxide detectors are inexpensive and readily available, both as a battery-operated unit and as a unit that plugs into an electrical outlet in the home. No home should be without this safety protection, and homes with gas-fired equipment (natural gas or LP propane), space heaters, or other sources of risk should be extra cautious. Smoke detectors do not protect against carbon monoxide poisoning, and the opposite is also true. Carbon monoxide detectors do not warn of smoke or fire.
Inspecting Buildings for Visible Evidence of Conditions Likely to Produce Dangerous Carbon Monoxide Gas
The fact that you cannot see nor smell dangerous carbon monoxide gas does not mean that there is nothing to look for when assessing the safety of heating equipment. Not only are there easily spotted installation errors (the first list below), there may be more subtle but easily visible errors if you know what to look for (the second list below).
Visible building conditions risking carbon monoxide hazards
This is by no means the complete list of errors that can cause dangerous carbon monoxide exposure in buildings, but here are some common foul ups outside of the workplace that can cause dangerous levels of indoor carbon monoxide:
• Space heaters: improper use of gas or kerosene fired heaters can produce high indoor CO levels. Warning: Never go to sleep in an enclosed space with a space heater left operating. In addition to the CO hazards there is a risk of oxygen depletion which can also lead to asphyxiation.
• Gas fired central heating equipment combined with:
o Improper venting, blocked, under-sized, over-sized, missing parts, improperly sloped chimney or flue. A variety of errors can cause a failure to vent combustion gases out of the building, allowing dangerous flue gases to build up indoors.
o Inadequate combustion air. If a heating appliance is installed in a small confined space it must be provided with outside combustion air. A service technician may tune and inspect a gas-fired boiler with the boiler room door open, finding that it seems to operate fine. When s/he closes it on leaving, there may be an inadequate or no opening for combustion air into the room.
o Venting small appliances into large cold chimneys: Installation of small, higher efficiency gas-fired equipment into old homes at which the appliance is vented into a large (cold) masonry chimney. In such instances the heater may never develop sufficient heat and draft to actually vent up the chimney.
o Also sometimes water heaters are left venting into a too-large, too-cold masonry chimney after a gas-fired boiler is converted to a high-efficiency direct-vent (no chimney) unit. One of my clients developed headaches every October - an event I traced to this condition in Poughkeepsie, NY. [DF re E.B. case 1988].
• Car exhaust, such as to occupants of rooms adjoining or even above a garage where car engines are left running
• Un-vented gas fired water heaters often found venting directly into a basement utility room or even directly into a living area or bedroom.
Other clues which can suggest a risk of carbon monoxide hazards in buildings
• CO detector alarms Do not ignore this first line of defense. Install CO detectors near the heating equipment as well as in sleeping areas of the home. People have died after not believing their CO detector and taking out the batter to silence the annoying device which they believed was malfunctioning.
• Missing parts: Gas fired water heaters, furnaces, boilers which are missing flue vent connector components such as draft hoods and flue gas spill detection switches - it can be difficult to spot that something is missing unless you know what's supposed to be there. Review this topic with a trained heating service technician or plumber.
• Clogged heater draft hood from hair or other debris
• Signs of flue gas spillage Blocked flues will result in combustion gas spillage back into the building. Often this will cause:
o Rust on heating equipment at the point of flue gas spillage - you can detect this even when the equipment is not operating
o Rusty debris on the top of gas fired heating equipment below the draft hood
o Water condensation on building surfaces may occur if gas-vented appliances are venting back into the building, especially on cool basement surfaces - you can only observe this when the equipment is operating
o Odors of combustion products: while CO and CO2 are themselves odorless, if they are spilling from heating equipment, odors of other combustion products may be notices.
Testing for Carbon Monoxide
In addition to the installation of CO monitoring alarms in buildings, a variety of electronic and gas sampling equipment is available to make spot checks for hazardous gases.
While a "positive" indication of a gas is an important indicator of a hazard, a "negative" or "not found" result is nothing to rely on.
The fact that dangerous levels of CO are not present in a building at a particular instant is absolutely no guarantee that dangerous levels of CO (for example) may not occur even moments later. For example, opening a window, turning on a fan or clothes dryer, closing a door and similar innocent acts can significantly change air flow, combustion air, and other building conditions.
Therefore spot tests for dangerous gases should not be relied upon to guarantee building safety. This is why the list of visual inspection items and proper heating equipment maintenance are so important.
MEDICAL EFFECTS of CO - Medical effects of Carbon Monoxide (CO) Poisoning
Many sources I (DF) reviewed indicated that if carbon monoxide exposure was sub acute, that is if the person did not lose consciousness and was removed from the CO exposure before losing consciousness, then any medical effects were temporary. Indeed detection of CO exposure at a hospital is problematic since CO leaves the bloodstream quickly once a person is exposed to normal air. However there is evidence that lasting physical damage may occur from carbon monoxide exposure, though the popular press has not (2006) discussed the exposure level and duration necessary for these effects.
Heart muscle damage occurs from Carbon Monoxide (CO) exposure, screening recommended
31 January 2006 - The New York Times Science Section reports on a new study, released in JAMA's January 25 2006 Magazine Issue, and which indicated that people exposed to carbon monoxide suffer damage to their heart muscles and are at much greater risk for heart attacks in later years. The Times article asserted that CO Poisoning results in 40,000 emergency visits a year in the United States - the most common accidental poisoning event in the U.S. with an annual average accidental death rate of about 1000 people and average suicidal death rate of about 2400 people. [U.S. CDC] Five percent of such patients die in the hospital. Research was not cited regarding sub acute exposures and exposures which do not result in a visit to a hospital. -- New York Times Science Section, January 31, 2006 p. F6, "After Crisis, Carbon Monoxide Still Takes a Toll."
The carbon monoxide exposure and heart muscle damage study was led by Christopher R. Henry, Minneapolis Heart Institute Foundation, in the current [Jan 2006] Journal of the American Medical Association The study examined the medical history of 230 people exposed to carbon monoxide and treated at hospital between 1994 and 2002, following their health to 2005. After 7 1/2 years, in this otherwise low risk (of heart failure) population, 25% of the originally-surviving patients had died - a rate about three times the average heart failure death rate statistic. For people who had suffered heart muscle damage the mortality rate was 38% with half of the mortalities being (apparently) traced to cardiovascular problems. The study concludes that people who are exposed to carbon monoxide should be screened for heart muscle damage. Heart muscle damage from CO poisoning (in the study) was characterized by elevated levels of cardiac troponin I (a type of protein) or creatine kinase-MB (a type of enzyme), and/or changes in diagnostic electrocardiogram (ECG). -- DJ Friedman paraphrasing the NY Times article and JAMA's news release regarding this study.
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Ductless Mini-Split
There are occasions when it is physically impossible or impractical to install a central air conditioning system or heat pump. Through-the-wall and window units are noisy, drafty, and allow unneeded air infiltration when not in use that can waste energy and allow insects or other pests to invade the home or office.
Split systems offer higher efficiency and reduced noise without a large hole in the wall or an open window. By separating the compressor and condenser coil from the fan and evaporator coil, the noisiest component is away from the room. The indoor unit will usually have remote control capabilities and a timer to cycle the system only when needed. The indoor unit is called an air handler because it has the evaporator coil, blower, and controls inside. The outdoor unit is called the condenser. They are connected together with refrigerant piping and control wiring, similar to a central system.
Some manufacturers use low voltage to control the system, others use line voltage. Caution must be taken when opening up the cabinet to shut power off when servicing. The most important service item is dirt. Screens or filters can usually be found behind the front grill of the air handler. Tabs allow them to slide out for cleaning. Keep vegetation and debris away from the outdoor unit to allow good air flow for maximum cooling efficiency. An occasional blast from a garden hose with the system shut down will help keep the condenser clean.
Relatively new to the American market, ductless split systems have been in use in Japan and other markets for a long time. Until recently none were of U.S. manufacture, but increased demand changed that.
To further meet demand, some now offer gas heat as well as heat pump capabilities to increase efficiency and allow for lower design temperatures.
Ductwork & Distribution
You've done the heat loss, and chosen a furnace or air handler. Now you have to design a system to distribute the conditioned air to each room. This system will be based on the cfm output of the blower, and the total cfm will have to be distributed proportionally to the rooms according to their needs. The BTU and cfm output will seldom match exactly the house's requirements, so the extra will have to be rationed out. The furnace will have a specification sheet which will list the various blower speeds and outputs.
There are numerous methods of designing a ducted heating or cooling system. And if we sat around thinking hard enough, I'm sure we could come up with a couple more. We could engineer the heck out of the situation if we wanted to, but most of us don't get paid for creativity or unusual design techniques, so I'm going to review one proven method, and leave it at that.
In technical terms, the system will be a low velocity, reducing extended plenum perimeter system. It is more work saying it than installing it. In simple terms, it means that the trunk line tapers as it goes, and that the supply outlets will be near the exterior walls, in this case the floors, and the returns will be located on the inside walls. The ductwork size, as always, is based on the friction component of the moving air versus the duct itself, and the blower’s ability to counter this friction. Again, what this really means is that the air doesn't really want to move, but the blower will move it anyways. It is always noted in units of inches of water, or In. W., and the velocity, or the speed of the air will be in FPM or feet per minute. These concepts and abbreviations are useful and helpful in their own right, but rapidly lose their value when you are crawling around on your belly measuring a trunk line through a crawl space, or dripping sweat in a two hundred degree attic. For residential applications with limited duct lengths, get one of those rotating duct calculators from a salesman, set it at point 1, and go; the chart below, approximates the cfm while the fpm remains under 700 for branches and 1000 for trunk lines (Supply branches should be limited to output maximums of 8000 BTU for heating, and 4000BTU of cooling unless construction methods dictate otherwise, and should always contain a manual damper for air flow adjustment).
Duct Design and Dynamics
There are several common numerical factors in home construction. "Sixteen inch on center" refers to the distance between wall studs and floor joists. One quarter inch per foot represents the pitch of a drain pipe. One hundred CFM, cubic feet per minute, is the basis for duct design.
For heating with a gas or oil furnace, 100 CFM represents approximately 8000 BTU per hour.
For air conditioning, 100 CFM represents 6000 BTU.
The standard eight inch deep duct is designed around this 100 CFM standard. Every two inches of width equals 100 CFM. A six inch round duct also equals 100 CFM. So for every two inches of width of an eight inch trunk line equals a six inch round.
Begin with two inches of duct width for friction loss, and the formula for 1000 CFM will be 2 + (2x10)=22 for an 8 inch by 22 inch duct which will supply ten six inch rounds.
Before the ducts can be designed, the size of the furnace and/or air conditioner must be determined. The above 1000 CFM would match an 85000 BTU oil or gas furnace with 30,000 BTU of air conditioning; also refer to as 2 1/2 tons; a ton being 12000 BTU of cooling. The 8 by 22 duct would feed 10 six inch round outlets.
What goes out must come back, so the return system must be the equivalent. Returns are usually fewer in number and of larger diameter but must equal 1000 CFM total.
Efficiencies
Energy conservation has become an important part of the environment. Manufacturing equipment and maintaining it for peek performance is a priority. The Federal government has also established guidelines for minimal efficiency ratings on equipment. Electric powered machines, for example, air conditioning systems, used to rated with a C.O.P.(coefficient of performance), which was a ratio of output divided by input. Useful to engineers, this factor did not give consumers much to go on. To improve comparison shopping, a new rating EER (energy efficiency ratio) was added to the specification tags on A/C units. This is a ratio of cooling capacity in BTUs per hour divided by the electrical power in watts. Since this number could vary under different climatic or room temperatures, a new rating, SEER (seasonal energy efficiency rating) became the current guideline. This is an EER adjusted to be an average rating for operation of the machine over a wide range of conditions. Energy conservation has become an important part of the environment. Manufacturing equipment and maintaining it for peek performance is a priority. The Federal government has also established guidelines for minimal efficiency ratings on
Minimal ratings for residential central air conditioning system have been set at 10. Higher efficiency units will use less electricity to run, but are more expensive to purchase. The consumer must weigh the installation cost against the amount of use the system will get. The new gas powered heat pumps are rated at a remarkable SEER of 27 or higher, and operate similar to a co-generator (the heat produced by the engine that powers the compressor is added to the heat pump circulation of refrigerant). All air conditioning and heat pump units must have a SEER rating from the manufacturer. Window units, central systems, splits, rooftops, etc., must carry a label with the information listed.
When a technician adjusts the air-to-fuel mixture on an oil or gas burning appliance (some gas units are preset by the factory and cannot be adjusted), a comparison is made between the heat of combustion and the heat of exhaust. The heat captured by the exchanger is it’s efficiency. With the help of instruments and charts, conditions for clean combustion, such as smoke and carbon monoxide or dioxide or oxygen output become part of the computation, and an efficiency rating in percentage can be determined. This is done on site. The manufacturer is required to test the appliance under a variety of conditions and give it a rating as A.F.U.E. (annualized fuel utilization efficiency). Similar to the SEER rating, it gives the consumer a guideline to use toward the purchase of the furnace or boiler. A label must be attached to the machine listing this information.
The labels affixed at the factory listing the efficiency rating does not have to be permanent. Improvements in equipment are being made constantly, and the labels may change more often than the cabinets of the appliances.
Energy Conservation
Heat is energy. Conservation is needed to keep energy inside (heating season) or outside (cooling season). In the 1970's, the rumor spread that the earth would soon run out of energy. Numerous laws were enacted to conserve energy and invest in renewable resources, including wind, wood, and solar energy. Lower speed limits reduced fuel consumption. The fuel shortage has disappeared, Detroit is producing gas-guzzlers again, the speed limits are back up, and there are no longer incentives for alternate fuels. The only hangover from the energy conservation effort is the insulated floor over a basement that is not vented to the outside.
Anyone who has ever handled fiberglass insulation knows that it is not compatible with the human body. In 1994 the Federal government labeled fiberglass as a possible carcinogen, but lobbying convinced congress that people would not normally come into contact with it in everyday life. In most houses it is buried behind the sheetrock in the walls or above it in the attic. The basement is different. Many people use their basements regularly. Children play there; washers and dryers are sometimes located in the basement. Fiberglass in the floor joists rains dust down as people walk on the floor above, creating a layer of fiberglass dust on the floor waiting to be stirred up when someone walks through it. Any carpenter or technician who has to work in the insulation years after it was installed can tell tales of the mice residing in it, and the unhealthy residue they leave behind.
Does it insulate the first floor from the cellar? Yes, but the temperature difference is probably only 10 or 15 degrees. Is it worth the health risk? Probably not. A quick trip to the attic will show why. The ductwork in the attic is wrapped with R-8 insulation. If there is an air handler up there, it has even less insulation in it. The heating and cooling system is insulated with R-8 or less, over a ceiling insulated to R-38. The 68 degree air inside the house is insulated at R-38, while the 100 degree air inside the duct is insulated with R-8. An extra 25% was added to the system to compensate for loss into the attic.
Why not take the insulation out of the floor joists in the basement and put it over the ductwork in the attic? It would increase the efficiency of the attic system, eliminate the health risk in the basement, and not break any code rules by keeping the house at the AVERAGE energy conservation number as required. It is permissible, as per section 502.2.2 of the International Energy Conservation Code, to over insulate some areas and under-insulate others, so long as the building does not lose more energy because of this action. In this case, the savings could be as much as 20%, if the system does both heating and cooling.
It would also make more sense to insulate the walls of the basement. This would keep the heating system and the plumbing system in conditioned space.
If you are building a new house, take a copy of this to your building inspector and get his permission to make this alteration.
Also, never insulate the floor over a crawl space. Insulate the walls of the foundation. It will keep the space drier and eliminate the housing for rodents.
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Light Commercials
Ductwork Installation
When I was writing my “Ductwork Installation Guide” I've considered that the next guide going to be to light commercial ductwork installation. But I wasn’t sure that there is a market for this kind of a manual.
However, nowadays slump in the house market is driving HVAC companies from residential to light commercial installation. If you are working in this kind of company you may face a different environment and meet unexpected difficulties.
In general, light commercial installation is easer than the residential one, but it is require a different approach and an installer constantly finding different types of equipment and ductwork to install. Someone can do the work for 10 years and still to find something new . Also different kinds of commercial buildings will make an installer to run even familiar system of ductwork differently. So, I've decided to create this page on my website.
The purpose of this page is:
- To help newcomers with all my knowledge to accommodate a new profession.
- To find out for myself if anyone actually needs this kind of help.
So, if you have any questions you can cotact me on this page.
Here you can see some pictures which I took long time ago for the “Light Commercial Ductwork Installation Guide”:
  
Supply duct Supply duct above the sprinkle line Y-branch
  
Connection of the supply duct to the plenum Smoke detector Floor penetration
  
8” heat run 8” heat runs Duct hanging
  
Bath fans exhaust pipe Diffuser connection Linear Register
Question:
“me and a guy are hanging commercial duct we both have 10+ years experiance between us when we come off the sicissor lift to look down at the duct work it looks twisted, we are very experienced at hammering duct work together, i dont get why it is twisted, the duct goes together easy with drives”
So, here are several rules you have to follow when running the duct:
1. Hangers:
- It’s always better to put all hangers on for the same duct size.
For example, if you have to install 40’ of 30” x 14” duct and the distance between trusses is 6’ you have to hammer on 6 pairs of hangers.
- When you are measuring where the hangers should be cut, use an electrical conduit. They are always 10’ long and it’s very easy to put on an additional piece to length.
2. Ductwork:
- When you snap a piece of duct together it would be better if sides are matching, but it’s not a big deal if not.
- Don’t put any screws in the seams.
3. Hanging the ductwork:
- Every next piece of duct must be hung with the seam on another side.
- Don’t screw a hanger to the bottom of the duct if there is a seam.
- Don’t try to fix twisted ductwork until first transition or 90* is installed or all the system is done.
- If the system of the ductwork is twisted push the corners which are down and up from both sides.
- Secure you job with the screws at the bottom of the ducts.
Space Cooling Load Calculations
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Adjustable curb Tall cone Curb
  
Zoning, bypass damper Round ductwork Zoning damper
Question: I would like to know how the hangers are attached to metal beams. Also were the fire dampers should be in commercial applications.
Thank you.
Answer: Hangers or straps usually are attached by “Caddy strap hangers”. There are several types of them, but   the most usable are shown on fig.1 (twisted) and fig. 2 (straight).
In order to attach the hanger strap to the “Caddy strap hanger” you have to fold approximately 1” – 1 ½” of it by using simmers, long nose pliers or hands, hook up the caddy strap and smash the hanger strap with the hammer. After that you just have to hammer it to the metal beam.
Because there are many types of metal beams some of them are thinner and some of them are thicker the “Caddy strap hangers” are made to fit thicker or thinner applications.
Fire Dampers
Fire Dampers are typically intended to be used as part of the HVAC duct system when passing through a fire rated barrier (walls, partitions, floors). The trigger mechanism is a heat fusible link that when activated, impedes the migration of high temperatures into and through the duct system.
UL, AMCA and Damper Manufacturers Require "once every 6 months" Damper/Actuator cycling to ensure proper operation of fire/smoke and smoke rated Dampers during a Fire event.
Fusible links
Fusible links are temperature sensitive fire protection devices designed to be part of a fire protection system. The system is activated when the ambient temperature increases to the point that causes the fusible link to "break-apart". At the point of breakage, it releases the pre-loaded fire protection device, thus restricting the spread of fire.
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Please watch 11 video presentations. If you'll find out that you need any fan from the list below, please contact me on this page and you will get the lowest price guaranteed!
List of the videos:
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