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Q. I'm asking about where to put a Carbon Monoxide detector. I just bought a house and the detector is on the 2nd floor. Shouldn't it be on the main floor instead, where the fireplace is, or in the basement where the furnace is?
A. I recommend that one have two CO detectors and to put one in the master bedroom because if you are going to succumb to CO poisoning it will most likely happen while you sleep. If the house fills with CO to a toxic level and you are awake you will present symptoms and do something about it such as leave the house to seek help. Health effects from exposure to CO levels of approximately 1 to 70 parts per million of air (ppm) are uncertain, but most people will not experience any symptoms. Some heart patients might experience an increase in chest pain. As CO levels increase and remain above 70 ppm, symptoms may become more noticeable (headache, fatigue, nausea). As CO levels increase above 150 to 200 ppm, disorientation, unconsciousness, and death are possible. Compare that to normal oxygen levels in air at roughly 200,000 ppm-- so it doesn’t take much CO to cause lethal results.
Remember not to install carbon monoxide detectors near fuel-burning appliances such as a stove, gas fireplace or furnace, as they may emit a small amount of carbon monoxide upon start-up. A CO detector should not be placed within fifteen feet of very humid areas such as bathrooms.
When considering where to place a carbon monoxide detector, keep in mind that although carbon monoxide is roughly the same weight as air (carbon monoxide's specific gravity is 0.9657, according to EPA while the specific gravity of air is one), it may be contained in warm air coming from malfunctioning combustion appliances such as home heating equipment. Carbon monoxide will rise along with the warm air.
Chicago required CO detectors in 1994-- much of the city heats with gas-- and the combination of everyone cooking Thanksgiving dinner and an atmospheric temperature inversion over the city that day caused hundreds of CO detectors to go off, creating havoc with the city emergency response services. UL later changed the CO standard 2034 (1998 revision) with stricter requirements that the detector’s alarm must meet before it can sound. As a result, the possibility of nuisance alarms has decreased.
Q. I live in a typical Cape St. Claire 1968 Split Foyer. The foundation is poured concrete, the front of the home is at grade level, the rear of the house backs into the ground about five feet. Along the back wall of the foundation I have horizontal cracks in the concrete. The cracks are about two feet above ground level and three feet long in two different areas. I can't tell if the cracks go through to the inside of the home since the inside of the walls are finished. These cracks have been here since we moved in seven years ago. I haven't seen a noticeable change in them, not to say they haven't crept a bit each year. Do I need to be concerned about these? If so,what actions should I take?
A.They sound to me like common curing cracks. As concrete cures it shrinks ever so slightly and to a great degree has to do with the volume of water in the original mix. If they haven't noticeably changed size or length in seven years I wouldn't lose any sleep over them. A 1968 poured concrete foundation was either chuted directly from the back of the concrete truck-- also called a transit mixer-- or run up on planks in wheelbarrows and dumped into the forms. In either case the concrete was probably made extra "plastic" by site adding water making the wet concrete flow easier. I'll bet the mix that went into those foundation forms back in the day was pretty sloppy. Such wet concrete is so much more susceptible to drying or curing cracking than stiffer, less plastic, less wet concrete.
Nowadays, the great majority of house foundations are poured concrete and the use of great big boom trucks with concrete pumps that the transit mix trucks dump into make pouring solid concrete foundations fast and so much less labor intensive. The real work is setting up prior to the pour and then stripping the forms the next day or so after the concrete has achieved its initial set. There are specialty crews that travel from site to site doing only solid foundations and they are very good at it. The cure to full working strength is 28 days and continues a long slow cure for the next fifty years plus. I've seen concrete pile caps placed by the Romans under the temple at Bath England that looked as good as the day they were poured over 2,000 years ago! I'd consider caulking those cracks closed to prevent potential insect intrusion. Be neat doing that because a concrete repair always looks like a concrete repair.