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Where to Properly Place Carbon Monoxide Alarms


Question:  I keep hearing conflicting opinions about whether to install carbon monoxide alarms high or low. Some people say that CO is heavier than air and is more likely to set off an alarm near the floor. Others say it is lighter than air and advise installing alarms near the ceiling. What is the truth about this, and what is the best place to install a carbon monoxide alarm?


Answer:  This question comes up frequently in the course of home inspections, and incorrect information about carbon monoxide has become commonplace. So here are the facts. At standard temperature and pressure, the weight of air is 0.0807 pounds per cubic foot, and the weight of carbon monoxide is 0.0780 pounds per cubic foot. Considering the positions of the decimal points in these numbers, these differences are miniscule, making the relative weights of air and carbon monoxide nearly equal, with carbon monoxide being very slightly lighter. So what’s the best position for alarms, high or low?



To answer this question, an experiment was conducted in May of 2011 at the Center for Hyperbaric Medicine at Virginia Mason Medical Center in Seattle, Washington. The purpose of the test was to observe the way that carbon monoxide mixes with air and thus to determine the safest placement for carbon monoxide alarms, to provide the earliest possible warning of CO contamination in a home.


An eight-foot-tall Plexiglas chamber was constructed and three carbon monoxide alarms were installed, one in the top portion, one at the bottom, and one in the middle section. Carbon monoxide was then injected into the chamber in a series of tests. Sometimes, the CO was injected at the top, sometimes at the bottom, and sometimes in the middle. In each case, the CO diffused so rapidly with the air that there was found to be no apparent advantage in placing a CO alarm high or low inside a home.


What matters when installing CO alarms is to place them close to all bedroom entrances and to have one on each level of a multi-level home. Although not required, it is also advisable to install a CO alarm in the garage, since an idling vehicle is a likely source of carbon monoxide. And be sure to test each alarm regularly to make sure it remains operable.

Source: The House Detective: by B. Stone



Recommended Regular Maintenance For Your New Home


Home Maintenance Checklist


  Monthly (on or around the first day of the month)


  • Test and clean/dust smoke and carbon monoxide detectors

  • Test GFCI/GFI receptacle/breaker and outlets

  • Replace/clean heating, ventilation, air conditioning (HVAC) air return filters

  • Check grout/caulking in tile and marble in wet areas (showers, sinks, etc.); repair as needed


  Quarterly (on or around the first day of January, April, July, and October)


  • Check range hood charcoal filter; replace/clean as necessary; repair as needed

  • Check caulk seals between countertops and walls and on any laminated surfaces; repair as needed

  • Check, and adjust as necessary, thresholds, door sweeps, and weather-stripping on exterior doors to maintain air tightness

  • Oil all moving parts and tighten nuts and bolts on garage door(s) and tracks; check garage door opener(s) and sensors

  • Remove leaves, debris, and snow from window wells

  • Check dryer vent exhaust for lint blockage; clean as needed

  • Thoroughly check showers and wet areas for mildew


  Spring and Fall Maintenance (on or around the first day of April and October)


  Perform all monthly and quarterly maintenance in addition to the following (where applicable):


  • Clean gutters, downspouts, and roof eaves to remove leaves and debris

  • Check connection between dryer and vent exhaust; repair as needed

  • Check washing machine hoses and connections for cracks and leaks; repair or replace as necessary per manufacturer

  • Have an HVAC professional inspect and calibrate your heating and cooling system (start of heating and cooling season)

  • Vacuum/clean window and sliding door tracks; lubricate with silicone spray

  • Assess all exterior paint and caulk; check exterior caulk seals around windows, doors, etc.; repair as needed

  • Drain and flush out hot water heater and verify that pressure relief valve is working (carefully follow manufacturer’s instructions)

  • Inspect and maintain the flow of all swales, and culvert and drainage inlets and outlets

  • Verify no standing water in crawl spaces, all insulation is intact, and heating/cooling supply lines are secure

  • Before the first freeze, disconnect exterior hoses and devices from hose bibs; if possible, shut off water to bib and drain

  • Inspect the home’s foundation

  • Verify sprinkler system is functioning properly and adjust/repair as needed

  • Flush out the sprinkler system in spring; prior to winter, flush out and drain the sprinkler system


  Summer (on or around the first day of July)


  Perform all monthly and quarterly maintenance in addition to the following (where applicable):


  • Verify HVAC condensate drain is flowing freely while air conditioning is running

  • Verify the float switch or overflow pan on a second-floor air handling unit is clear of obstructions and functioning properly

  • Verify main water cutoff valve is accessible and functioning properly

  • Have professional chimney sweep inspect and clean fireplace flue/chimney; check caulk around fireplace facing and repair as needed

  • Apply water-seal treatment to all outdoor exposed wood (power-washing wood first may be necessary)

  • Inspect roof for loose or missing shingles or flashing

  • Clear/clean weep holes in brick siding

  • Service septic system


  Winter (on or around the first day of January)


  Perform all monthly and quarterly maintenance in addition to the following (where applicable):


  • Remove ice buildup, snow, or any debris from roof when needed to prevent leaking

  • During extreme cold, leave indoor faucets located on exterior walls dripping to prevent pipe freezing


This checklist covers some basic, necessary maintenance items for most homes. It is by no means all-inclusive. Some items may not be applicable for the type of home and home features you have. For full details, please consult all guides, warranties, and literature provided by your builder, as well as the specific warranties and manuals for your home’s various appliances.


Source: 2010 PulteGroup, Inc.



Air Filters


Dirty air filters reduce air flow and increase the energy use of your home's heating and cooling system by 5 – 15%.

To keep your ventilation system operating at peak efficiency, and the interior environment as clean and healthy as

possible, change your air filter regularly.


Change Air Filters Regularly


Based on your specific system, or for health-related reasons, you may need to change filters as often as monthly or at

least quarterly. Check your equipment guide or contact your Heating & Air Conditioning representative for more information.

Air Filter Options


Efficiency is the measure of the number of particles and contaminates removed from the air by your air filter. Efficiency is extremely important when you, or a family member, have asthma or allergies.


Air flow is also very important to your home's heating and cooling equipment. A clogged air filter can create a reduction of air flow that may cause equipment to malfunction or stop operating altogether. Additionally, excess dirt in the filter could migrate and cause damage to motors, fans or coils. It's the air filter's job to clean the air before it gets into your equipment.


So how do you balance between efficiency and air flow? Well, for each household it is different. Each home has a best balance. There are several designs to choose from when picking your home's filter of choice as this article will point out.


This article is not about price, but about options and recognizing the necessity of proper maintenance.  It is important to be aware of your air filter capabilities and to determine what works best for your equipment and home. A variety of air filtering and purification options you can choose from. While costs vary, some options perform more efficiently than others.


There are several types to choose from:


  • Electrostatic air filters rely on electronic static or electricity and do not block air flow to your heating and cooling equipment. Because you are not blocking the air flow, the equipment is more apt to operate without issues such as clogging. The electrostatic Air Filter is not as efficient for removal of air contaminates as some of the alternatives. If your body is not sensitive to household inhabitants, this is an excellent choice for getting the most time out of your heating and air unit and its efficiency for clean air is over 90%.

  • Fiberglass panel filters - can be purchased at any store very inexpensively. The “you get what you pay for” mentality applies with this filter option. The fiberglass filter traps the large dust particles which will quickly build up causing airflow issues. These filters need replaced frequently. If not, your chances for equipment maintenance issues and/or breakdown increase significantly

  • Pleated air filters - are a very popular choice for homeowners.

    • While available in sizes from one to six inches, people usually select a design of two inches or less. Many builders use these filters because of availability, durability, costs; and they work. There are several varieties, some of which include odor control and electrostatic options, wire mesh etc.

    • Air particles land on the cover of this type of filter, as opposed to getting inside. Remember, the more the air is filtered, that much less air flow comes through the unit. Therefore, the folds add surface area to collect particles while allowing plentiful air flow.

    • If you have allergies, you can still use the pleated air filter, but need to find one with a Merv rating of 10 or 12.

  • HEPA (High Efficiency Particulate Air) media - stop particles and contaminates from going further. If you have allergies or asthma this may be the filter for you.

    • HEPA media removes dust mites, pet dander, pollen, mold spores and household allergens while providing maximum dust removal.

    • This filter is over 99% efficient and has more pleats per inch than the other pleated filters which increases airflow.

  • Activated carbon air filters are used for buildings heavy with smells or odors.

    • Gas, cigarette smoke, animal and garbage odors can be remedied by using this charcoal based filter.

    • It is not as efficient as some of the other options but you will be able to minimize use of unnatural sprays and colognes to camouflage odors.


Again, whatever you choose, please be sure to clean or replenish your filter on a regular basis.


Filter maintenance is the key to a healthy indoors and keeping your heating and air system working efficiently and effectively. 



Perceived Hazardous Building Materials


Often times, a home may contain certain perceived hazards depending on the house's age and the building materials used to construct and/or maintain it.  Most notably, these concerns involve asbestos, lead paint and formaldehyde in treated wood, however in some cases, these concerns may not be warranted.


The Consumer Product Safety Commission (CPSC) advises:




Even if asbestos is in your home, this is usually NOT a serious problem. The mere presence of asbestos in a home or a building is not hazardous. The danger is that asbestos materials may become damaged over time. Damaged asbestos may release asbestos fibers and become a health hazard.  BEST THING TO DO WITH ASBESTOS MATERIAL IN GOOD CONDITION IS TO LEAVE IT ALONE!  Disturbing it may create a health hazard where none existed before.


The Environmental Protection Agency (EPA) advises:


Lead-Based Paint


If your home was built before 1978, there is a good chance it has lead-based paint. In 1978, the federal government banned consumer uses of lead-containing paint, but some states banned it even earlier. Lead from paint, including lead-contaminated dust, is one of the most common causes of lead poisoning. If the paint is in good shape, the lead paint is usually not a problem. Deteriorating lead-based paint (peeling, chipping, chalking, cracking, damaged, or damp) is a hazard and needs immediate attention. Renovation, repair or painting activities can create toxic lead dust when painted surfaces are disturbed or demolished.




Formaldehyde is present in many consumer products, including composite wood products used in flooring, cabinets and furniture; wood floor and wall finishes; and is produced by combustion sources such as gas stoves and wood burning fireplaces. Laminate wood flooring is likely to contain some formaldehyde. However, formaldehyde emissions from these products have been reduced 80-90% from levels in the 1980’s and earlier due to mandatory formaldehyde emission standards in California (the CARB standards) and national voluntary formaldehyde emission standards (criteria established by the American National Standards Institute (ANSI)). In addition, formaldehyde emissions are highest when products are new and diminish over time so the longer a product has been in place, the lower the levels of formaldehyde likely to be emitted.

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