Bests & Worsts Reviews from Amazon

I didn't have a natural gas detector so I got this one to put in my basement, which is the only place in my home with natural gas. Installation is easy, just plug it in. The plug portion can be removed from the back of the unit and the main part located at a different level than the plug. Natural gas is lighter than air and propane is heavier so they recommend that it be located high in the room if you have natural gas and low if you have propane. A lot of the negative reviewers don't appear to understand when the unit is supposed to sound the alarm. Carbon monoxide is poisonous at high concentrations. Natural gas and propane are not poisonous but can be explosive at high concentrations, the levels are well established. At very high concentrations they can cause suffocation because they displace oxygen. The packaging says that it might take up to 4 hours to sound depending on the concentration of CO, this is consistent with the UL standard. In fact a unit would fail the UL test if it went off within 30 days when there are low levels of CO. This is to minimize nuisance alarms, the alarm wouldn't do any good if people got frustrated and disabled it. The gas detector alarm is specified to sound by the time the concentration reaches 25%, this is below the explosive threshold. Just because there is a heavy gas odor doesn't mean there is an immediate danger. One negative reviewer tried to test it with a cigarette lighter, which typically use butane. This unit is only specified to test for natural gas (methane) and propane. The warranty is 5 years, the unit will stop working after 7 years and should be replaced. This is a safety feature, not planned obsolescence.