High levels of carbon monoxide (CO), if found in the home, can pose grave risks or even the risk of death. Carbon monoxide is a by-product of combustion and can come from defective, improperly installed or worn out appliances, chimneys, vents and flues. Wood burning devices can be a source of CO. However, the most common suspects are oil, propane and natural gas appliances: water heaters, gas dryers, gas and oil furnaces, gas fireplaces.
One time, as a home inspector, I had a worried man call me. He was panicked that he might have a CO problem in his house. I asked him a few questions and he relaxed. It ends up that he had no wood burning devices and he had an electric hot water heater, an electric range and dryer, and electric baseboards heaters. That was one individual who did not have to worry about CO levels – unless he was sneaking a barbecue into the house during cold weather. He just plain did not have the devices in the home that create CO.
Personally, and it is beyond the standards of a regular home inspection, I run carbon monoxide tests with a standardized test meter. I do this if I have a concern about any appliance on promises– usually an older furnace, sometimes a water heater. By the way, most gas ranges, as the burners are being lit, put out CO – hence the strong recommendation for a range hood over gas ranges. I will hold the CO detector in different locations, such as at draft hoods or near heat exchangers, but I was taught by an HVAC professional that one of the smartest things to do is to put the meter on a heat supply register that is inside the home. That best simulates the level of CO exposure that is taking place in the home. For your information, here are a few key CO levels and what to expect from them. They are listed in parts per million, the measure that is used:
9 ppm – Maximum allowable concentration for short term exposure in a living area
35 ppm – Maximum allowable concentration for continuous exposure, over 8 hours, in industry
200 ppm – Maximum concentration allowable in a 15 minute period. Likely to cause headaches, nausea after a couple hours.
400 ppm – Headaches in a couple hours, life threatening after 3 hours. This is the maximum allowable CO in flue gas, so you can see why you do not want a leaky flue at the furnace or water heater.
12,800 ppm – Early instant death, 1 to 3 minutes to live. I know, there are many levels of CO after 400 ppm and up to this point but after about 150 ppm they are all bad for you.
Different home inspectors have different ways of looking at this issue. Some inspectors do not have, and do not want or plan to buy, a CO detector. Personally, if I have a fear of a furnace or any installation, I feel better knowing that I put the CO meter next to it. Obviously, if statements are high, I strongly suggest that the device will not be used until an HVAC technician has been able to evaluate and repair or replace the unit. In general, if I do not like the condition or age of the furnace, even if CO levels are normal, I still recommend that an HVAC technician evaluate and service the furnace and inspect the heat exchanger. A furnace, with any age on it, should be serviced annually. I run the CO test for my own peace of mind. That way I know that, even if the clients put off having HVAC service, they will not be exposed to dangerous levels of CO. I do not want a client going into a permanent sleep after I have inspected a house. Inspectors, who choose not to use a CO meter, will normally recommend HVAC service, as I described above, for almost every furnace.
I think that, without a person lives in a home with all electric heat and the appropriate electric appliances, the new, affordable CO alarms should be installed. These emergency "idiot alarm" devices for consumers are not at all the same as a CO test instrument. It takes high levels of CO to alarm the consumer units – they really are emergency devices. When these alerts go off, take it seriously – the device has either detected significant levels of CO or it has malfunctioned.
Specifications: A basic consumer CO alarm, unlike an expensive CO meter, has a time function tied to it as it reads the level of the concentration. If the sample is under say 100 ppm, the consumer alarm might not alert for several minutes. But, if it detects 400 ppm it will sound quickly. These units are analyzing the level of CO vs time to simulate the absorption of CO into the body. The element of time is added to the equation to make it less likely that there will be false alarms due to smokers, gas burners and that kind of thing.
When you install consumer CO alarms, position them as specified by the manufacturer – usually lower on walls. Unlike smoke alarms, you do not want them up on the ceiling. That works for smoke but it is not recommended with carbon monoxide, a silent and odorless killer.
Source by Steven L. Smith