Effective July 1, 2011 all homes must have carbon monoxide detectors installed as a conditition of sale. This means that, if you are planning to sell, or have your house currently listed, it is a good idea to purchase some of the detectors now. The requirement is much like that for smoke detectors that has been in place for years. It will be another item that inspectors look for and that you will have to sign for in disclosures. It's always best to know ahead of time of upcoming changes!