The House Detective: by Barry Stone, Certified Home Inspector
Dear Barry: 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? Jamie
Dear Jamie: 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.
The House Detective: by Barry Stone, Certified Home Inspector
Dear Barry: A few weeks ago, my landlord installed an old, unvented gas heater in my apartment. Whenever I use it, the place becomes as humid as a steam room, and mold has appeared on some of the walls. I’ve complained, but my landlord says the mold is caused by my dogs. Does that seem plausible, or is the mold caused by the heater? Elizabeth
Dear Elizabeth: Mold is caused by excessive moisture. The exhaust from a gas-burning fixture is mainly carbon dioxide and steam. Most gas heaters are vented to the outside, but an unvented heater expels exhaust, including steam, inside the building. If the mold began after the heater was installed, then the cause is obviously moisture condensation from the steam that is emitted by the heater.
As for your landlord’s canine excuse, that’s a dogged ploy if I ever heard one. Who ever heard of mold being caused by dogs? The unvented heater is a health and safety hazard and should not be used. Furthermore, if combustion problems ever occur with that kind of heater, you could have carbon monoxide instead of carbon dioxide, and that could be deadly. Your landlord should address this matter immediately. First, the gas heater should be replaced with a vented heater, and the replacement should be done by a license heating contractor. Then, the mold should be mitigated by a qualified expert.
The House Detective by Barry Stone, Certified Home Inspector
Dear Barry: I recently bought my first home and was extremely proud of myself because I’m just 23 years old. I found an older home that needed some work and hired a home inspector who was recommended by my Realtor. The inspector found a few minor problems, so I bought the house. But 5 months later, the heating system failed. The repairman said the heat exchanger was cracked and was giving off carbon monoxide. If my home inspector had told me this, I could have had the sellers replace the furnace, or I could have bought another house. What can I do now? Julie
Dear Julie: If you haven’t already replaced the damaged furnace, you should contact your home inspector immediately and request a reinspection of the heating system. If the crack or any related defects are visible and accessible, then the home inspector would be liable for failing to disclose those conditions.
In many cases, cracks in a heat exchanger are located within the dark recesses of a furnace and are not visible to a home inspector. Sometimes, however, there are symptoms that can alert a home inspector to potential problems with the heat exchanger, such as irregular flame pattern, abnormal flame color, or soot near warm air registers or inside the flue pipe.
The big question, therefore, is whether faulty furnace conditions were visible at the time of the inspection. If so, then the inspector would bear some liability for negligence. Be aware, however, that the degree of liability could be limited by the wording of the inspection contract, by state laws, and by the inspector’s willingness to take responsibility for the consequences of a professional error.
Dear Barry: We are first-time homebuyers and have made an offer on the condo we are presently renting. We’re trying to decide whether to get a home inspection, and several friends have advised us to save our money. They say we can do away with it because the condo is priced very low and the equity will more than cover the cost of needed repairs. Are we taking a big risk if we buy without having an inspection? Jean
Dear Jean: My email box is littered with laments from homebuyers who bought homes without having them inspected. In many cases, their decisions were based on well-meaning advice from friends and relatives or inexcusable advice from misguided agents.
The reasons given for bypassing an inspection are numerous and always erroneous. For example, your friends say the equity in your condo will enable you to pay for needed repairs. But how will you know what those repairs are if you don’t hire a qualified home inspector? If there are problems with the electrical wiring, the plumbing, or the heating system, symptoms may not be evident until serious consequences occur.
Regardless of low price and high equity, you need to know the true condition of the home you are buying. You need to know that systems are not only functional, but safe and in compliance with applicable building standards. You’re preparing to buy a commodity that costs hundreds of thousands of dollars. Spend a few hundred dollars to protect that investment. But before you do, be sure to find the most qualified and experienced home inspector available.