Carbon Monoxide - The Silent Killer
With winter approaching, windows are being sealed up and furnaces are burning off the dust and grease from the summer. That is what you smell the first time you turn on the furnace in the fall. It burns off and the smell dissipates. Now everything is in shape for the heating season. Or is it! Any time we light a fire inside a living space, there is a potential for carbon monoxide production. The new tighter houses reduce the amount of infiltration of outside air so the dangerous gasses that do get into the house are not as highly diluted . This condition results in higher concentrations and a potential for disaster. Let's first look at what carbon monoxide is and how it effects the body.
Carbon monoxide (CO) is a chemical compound made up of one atom of carbon and one atom of oxygen. It is not the same as carbon dioxide, a relatively harmless gas we exhale and plants need to live. Carbon dioxide (CO2) is made up of one atom of carbon with 2 atoms of oxygen. Both are colorless, odorless gasses but the similarities stop there. CO is a deadly killer. When you breathe carbon monoxide (CO), it attaches itself to the red blood cells. The red blood cells are the delivery boys that pick up oxygen and deliver it to all the cells of your body. Once the CO grabs that red blood cell, it won't let go. It is very possessive too. It won't let the red blood cell go out with any oxygen molecules. If the red cells are hooked up with that evil CO, they can't take any more deliveries of needed oxygen to the cells and the cells begin to die from lack of oxygen. The more CO you breathe, the less oxygen is delivered to the cells and more cells die. First signs might be a headache, nausea, dizziness, shortness of breath and confusion but if the condition continues, death will ensue.
Carbon monoxide concentrations are measured in ppm, parts per million. 1ppm indicates there is one part of CO in 1,000,000 parts of sampled air. 9 ppm is the maximum indoor air quality standard. 50 ppm is the maximum concentration for exposure for 8 hours. 400 ppm will produce headaches in 1 to 2 hours and is life threatening after 3 hours. 800 ppm induces nausea and convulsions and death within 2 hours. 1,600 ppm produces nausea within 20 minutes and death within an hour and 12,800 ppm produces death within 1 to 3 minutes. These are average effects and the condition of the individual greatly effects the times. The young and elderly are more at risk as are pregnant women, anyone who is anemic or anyone with heart or lung problems. Keep in mind the effects are cumulative. Small concentrations over prolonged periods are also dangerous. So, what is a safe level and what is a desirable level aren't the same. 0 ppm is desirable while 9 ppm is considered safe under normal conditions. That is like saying 9 ppm is safe because it will only make you a little sick. It won't kill you!
So, where does this CO come from? Any time something is burned, the by-products are carbon dioxide and water vapor. Notice that is carbon dioxide, the good guy. Under ideal conditions, CO would not be produced but under poor burning conditions, CO is produced along with the CO2. This brings up a common misconception that all heating equipment produces CO. This is not necessarily true. Properly designed and adjusted equipment will produce little or no CO. Another misconception is that a cracked heat exchanger will cause CO. The CO is caused by a poorly adjusted furnace burner. The cracked heat exchanger will simply allow any CO produced to be brought into the home rather than up the chimney. This brings up another point. Furnace design limits the possibility of CO escaping into the conditioned air blown through the house. First the fire is contained inside a compartment inside the furnace. This compartment is called the fire box or heat exchanger. Air enters the fire box combines with the fuel and is burned. The by-products go up the flue or chimney. The air blown through the house blows around the heat exchanger and is warmed up by the heated metal. The blower is in front of the heat exchanger so it is blowing onto the heat exchanger. If there were a hole in the exchanger, this would tend to blow air into the fire area and up the chimney.
Technical note, science class information to follow; read at your own risk: There is another physical effect taking place in the heat exchanger. This effect is called the Bernoulli effect. Any time air blows across a hole it lowers the pressure and draws the inside gas out rather than pushing itself in. This contradicts the previous paragraph to some extent. This effect will be determined by the actual characteristics of the hole and where it is located on the heat exchanger. As you can see, there is more than one force acting on the system. Therefore, you can't rely on the pressurization around the heat exchanger to stop heat exchanger cracks from leaking potentially dangerous CO. Any apparent heat exchanger cracks are potentially dangerous.
It has been my experience that the biggest risk of CO poisoning is at the flue not at the heat exchanger. A blocked chimney will cause all the available CO to be diverted into the living space. No furnace check should be complete without a test for proper venting. Newer furnaces have blowers that blow the combustion air out. This is a good safety measure. However, if a water heater is also connected to the same flue ( which is common ) and the outside flue is blocked, the blower will blow the potentially dangerous flue gasses back out into the room at the water heater draft hood. Both vents should be checked.
Other CO producers can be fireplaces, stoves, ovens, space heaters, water heaters or any other appliance that contains fire. One particularly dangerous apparatus is an hibachi grill or charcoal grill. These fires by nature are slow burning and produce considerable CO. Wood stoves with a controlled burning wood fire also produce great quantities of CO. Cigarettes produce another fire that is a slow burning CO producer.
That should give you at least a working knowledge of the burning process and the production of the potentially lethal CO. Now, If the CO hasn't put you to sleep, this long dissertation probably has. Have a safe heating season. Monitor the CO levels in your house. Have it checked professionally at least once a year if you have an old furnace.
Next time we will talk about Radon, another potentially dangerous gas.
Here it is fall again. What ever happened to summer? While summer is often the best time to do all those outdoor projects, it is also the time to go on vacation, spend some leisurely time in the yard and who wants to work on the house when it is so hot? Well, I have to agree with the logic but time waits for no man and fall and winter are fast approaching. Ready or not, it is time to think about inclement weather. Before snow flies, you better get the exterior paining completed.
The most important thing to remember about quality painting is proper preparation. Painting is 80% preparation and 20% painting. Depending on the surface to be painted, you need to get it ready to hold paint. Paint is only as good as the first layer. If you paint over old loose paint, the newly painted surface is going to peal off. New paint will not hold on old paint! If old paint is flaking, it needs to be removed. The more effort you put into the removal, the better the new paint job and the longer it will last.
Old paint can be removed with scraping, sanding or chemical removers. Using a pressure water sprayer can also be used. Be careful with the high pressure to prevent damage to the wood. After using a water cleaning method, the wood must be allowed to dry thoroughly. I saw a house that had been power washed too well that had saturated the blown in insulation. The result was that the wood didn't dry out inside and the new pain ALL pealed off. It was terrible! So the word for power washing is "Caution".
Once scraped and sanded, bare wood should be primed with a quality primer designed for bare wood. Keep in mind, paint is not intended to span and fill cracks nor will it smooth a rough surface. It might look smooth when it is wet but as it dries and shrinks, it will conform to the surface below. If the surface was rough, the new paint will also be rough! The cracks and holes will still be there! The imperfections should be caulked until smooth. Only when you have a smooth primed surface, are you ready to paint! The older the house, the more the old paint layers and the more work to prepare.
Let's look at some paint characteristics. Water based paint is the most popular paint now. It covers well and clean up is easy. Older latex (water based) paint was not as durable as the oil based paint but new formulas form a good durable finish. One quality of latex paint is it's ability to pass water vapor through. Oil based paint is water proof and water vapor trapped below the surface will eventually cause the paint to blister. Blistering paint is an indication of a hidden moisture problem that should be investigated, not just scraped and painted over. Oil based stain penetrates the wood and gives it color but does not do much to protect it from sunlight and drying. I do not recommend using stain on wood siding unless it is cedar or redwood. DO NOT USE stain to protect plywood materials. It will usually result in a delaminating of the plywood that can not be repaired but must be replaced.
Wood decks should be treated regularly. The factory treating will prevent rotting and insect infestation but it will not reduce cracking and warping. Use an oil based penetrating protector at least every three years. If the deck is in the sun, more treating will be required.
Now that I have ruined your fall, perhaps you should just wait till spring and have it sided!
The dryness of last month is starting to give way to the changes toward spring. The weather is breaking and there are good days to work outside and soak up the ever increasing sunlight. Next month should bring the April Showers and a different moisture problem.
Spring showers are often aggravated by frozen ground unable to take on the new found moisture. With no other place to go the water runs along the surface of the ground often toward our foundation walls. As the water hits the foundation, it finds less dense soil in the backfill around the house and goes down into the soil along the foundation wall. If the wall is porous, some of the water will find it's way into the house crawl space or basement. This is only one of the problems we might encounter. Basement seepage soaks carpet, disintegrates box bottoms and rots away wood wall studs. It gives that musty smell to the lower levels. In crawl spaces, it might sit atop the plastic vapor barrier and evaporate only to and then condense on the band joist in the cool morning and evening.
Aside from the damage the water causes to wood and metal portions below grade, it also effects the soil around and under the house. Like many other materials, soil expands when wet and contracts when dry. This is particularly true with clay containing soils like we have. Saturated soil can press in on foundation walls enough to crack them. Saturated soil under a footing can heave it up like frozen soil. Another factor changed by moisture saturated soil is the bearing strength. Super saturated soil acts like quick sand in varying degrees and looses it's ability to support the weight of the foundation wall. If this happens, the foundation can settle. This condition is very apparent on front porches. Look for settled pillars on old porches. A limited footing pad is holding up the porch pillar and roof above. Notoriously, a downspout is located at this outer corner of the house and it dumps roof water into the soil at the corner and saturates the soil beneath the pillar and the pillar settles. The settling often causes the lowered gutter spill additional water and aggravate the condition more. Over years the pillar may settle six inches or more.
So, What is the solution? The correction for the problem is to get the water away from the house. All soil around the house should slope away from the house. Mark a perimeter of about 5 feet around the house and slope the soil about 1/2 inch per foot away from the house. Extend downspouts away from the house and make certain there are no curbings to stop the flow away from the house. Keep gutters and downspouts clean and check them for drainage. The next time it rains, get out the umbrella, and some boots and walk around the house looking to standing water near the foundation. For a professional evaluation, Call the House Doctor.
What about the baseboard drains installed in basements to keep the floors dry? This solution looks to control the water after it has entered the structure rather than keeping it from entering. I would recommend it in rare occasions only. In some cases it will actually encourage moisture to drain down the foundation walls and undermine the footings or further saturate the soil below the drain level, under the footings. Outside drain tile on the other hand, installed around the footings and draining to a daylight drain or to a sump pump is a good idea but these pipes can clog if they are overloaded by poor surface drainage. So, back to the bottom line. Get the water to run away from the house as much as possible.
This month we are feeling the effects of the dry winter air. Our furnace is superheating the already dry air and it's effects are multiplied. Water is a bit like a spouse. You can't live with them and you can't live without them. That is water! Too much water and we get mold and wood rot. Not enough and we get dry loose wood joints. Why do the joints loosen in the dry weather? They loosen because wood shrinks as it dries.
The shrinking wood causes things like popping nails in drywall. That's right, the nails are not coming out of the wood and popping through the drywall. The wood is shrinking away from the nail. The drywall follows the wood behind it and the nail now appears to pop out! Much of this shrinkage occurs when the house is built. The new wood is moist during construction and as the house is sealed up, the wood begins to dry. Cracks develop over doors and windows as the header shrinks more side to side than the stud does end to end. Normally, after the first major drying, the wood reaches equilibrium and if the cracks are repaired, they will not open up again. Unfortunately, this is not always the case. Seasonal changes bring moisture changes and wood expands and contracts. As it moves, the connected drywall cracks.
Ever seen this?
Truss lift is a common problem caused by this uneven swelling of the members of a wood roof truss. Look at the truss shown below. The lower portion of the truss that makes up the ceiling is insulated. It stays relatively stable. The upper portion of the truss that makes up the roof is uninsulated and open to the attic air. As moist air rises into the attic it hits the cold underside of the roof and condenses. This condensation deposits in the top portion of the truss. The moist truss wood now expands. As it lengthens, (shown in the upper right picture) it forces the peak of the roof upward. The lower ceiling section is connected by the cords of the truss and it is also pulled upwards and away from the wall below. These cords are exposed to the dry winter attic air which also causes them to shrink. A gap opens between the wall and ceiling. This joint is usually spanned by paper drywall tape and it is pulled loose. This loosened tape magnifies the problem.
This problem is often aggravated by settling or shrinkage of the center girder in the basement or crawl space. This movement allows the wall to settle down while the ceiling is pulled up. It is possible to limit the distortion of the truss but it is difficult to eliminate it completely. First we want to limit the amount of attic moisture. A properly installed vapor barrier helps limit moisture flow into the attic through the ceiling. Additional ventilation of the attic space sometimes helps. If bath vents expel warm moist air into the attic, the problem is worsened. Connect the bath vents to piping leading out of the attic space.
Modern construction methods allow the movement to take place but limit the gap produced by anchoring the perimeter of the ceiling drywall to the wall with clips rather than to the ceiling truss above. This allows the ceiling truss to flex upward and the drywall stays attached to the wall at the joint. Limiting attic moisture also helps restrict movement. Once improper construction is in place the only cure is to cover the gap with crown molding attached to the ceiling but not to the wall. As the ceiling rises, the molding rides up the wall and the gap remains concealed.
Depending on the amount of seasonal movement, filling the gap with an expansive caulk MIGHT work and allow the movement without cracking. Filling the gap with hard drywall compound and installing tape over the joint will usually end in failure of the joint after several movement cycles.
For a diagnosis of this type of problem, contact the House Doctor. Next month we will look at other moisture problems.
December and January are synonymous with holidays. We are now into the winter season and cold temperatures. There might be a few days to finish up those outside projects but chances are, they will simply have to wait until spring!
December brings the danger of fire to the forefront. Outside, we put up decorations that add electricity to damp and wet conditions. Water and electricity make bad bedfellows! Too often many strands of lights are connected to a single porch light receptacle. This receptacle might be rated at 60 watts and we connect hundreds of lighting watts. We often don't follow proper safety precautions while up on the ladder or roof hanging lights.
Inside, we introduce easily ignitable fuel in the form of a dry Christmas tree to dry winter indoor conditions. We increase the danger by adding heat producing lights to the tree. If this were not enough, this fire waiting to happen is set close to the effects of the fireplace. It all goes together, a dry tree surrounded by paper wrapped presents and adorned with heat producing lights. The stockings hung on the wood burning fireplace adds to the charm and danger.
So, the best advice for this time of the year is: Be careful! Think about safety whenever you are decorating. Wait as long as possible to put up the tree and take it down as soon as possible. KEEP IT WATERED! Use small Italian lights to limit the heat production and turn them off if you will be gone. Keep the tree as far from the fireplace as possible. If you are plugging the outdoor lights into the porch lamp socket, make a note for the job jar and plan on installing an outdoor receptacle with proper GFI protection.
Make this a safe Holiday season and enter the new year safe and well.
October is a month of falling
leaves and changing temperatures.
It is a time to start thinking about winter and the winter needs for
the house. It is time to get those outside chores done before freezing
temperatures make it impossible.
Getting the timing right for fall cleaning of the gutters sometimes requires the need for a crystal ball. The gutters should be cleaned just before the first freeze and after the last leaves have fallen from the tree. Cleaning too soon, results in late fall leaves clogging the gutters for the entire winter and early spring. Waiting too long can often result in frozen leaves filling the ice filled gutters. Speaking from experience, it is next to impossible to remove the frozen mess from the gutters even during a warm spell. The giant ice cube won't melt quickly. This frozen mass in the gutter can also aggravate ice dam problems on the roof.
There are new gutter guards that make the gutter cleaning process much easier. Be certain the gutter guards can be easily removed or folded back to get to the gutter to remove small particles that get through the mesh. The old expanded aluminum mesh would devour your hands long before the gutters were clean.
In the days of window air conditioners, it was common practice to cover the units if left in the windows. While this is still a good idea to prevent drafts from entering the house, covering outside central units is not recommended by House Doctor Services, Inc. If you feel you must cover the outside unit, leave enough opening around the bottom to allow for ventilation. The units are designed to protect themselves from the weather and adding a cover will often cause condensation on portions of the unit not as well protected from moisture damage. An example would be the under side of the top metal cover. Moisture in a covered unit will often cause condensation on the bottom of screws and they will rust.
Grading around the house:
Proper grading around the house diverts ground moisture away from the structure. This is advantageous all during the year but it has special significance in the late fall. Saturated soil that is frozen by early freezing temperatures causes the wet soil to expand more and can crack the foundation of the house. This crack is often evident just below the ground level in the basement where there are concrete block walls. The walls can be pushed in considerable. Over the years this problem could lead to major foundation problems.
If you have a freeze proof faucet, it is time to remove the garden hose. Late fall freezes can freeze the water trapped in the frost free faucet and split the thin copper tubing. The leak will be evident when the faucet is turned on.
Call the House Doctor for a pre-winter check up.
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