Sarah G. asked if adding a smoke detector to her security system is a good idea.
I believe that it is an excellent idea, and have both smoke detection and heat detection in my own home. Heat detectors are appropriate for kitchen and garage applications, and smoke detectors are suitable for all other locations in your home. If a fire breaks out in your home while the home is vacant, the detector will trip and the appropriate signal will be sent to your monitoring company to have them dispatch your local fire department to your home to hopefully put out the fire before there is extensive damage.
Many Homeowner Insurance companies give an extra discount on their premiums for having monitored fire detection. The devices made for monitored fire detection use a different technology than the non monitored devices that you purchase and install yourself in your home. Because of this, and other reasons, you can not tie in your Home Depot smoke detectors to your monitored home or business security system. Fire detection devices for monitored systems do not deploy at the first sign of smoke, and generally do not go off unless there is an actual fire, so false alarms are quite minimal.
If you pay for the fire detection device, your monitoring rate should not be any higher with fire detection than without it. If you are paying more for this service, you are being taken advantage of, and I would advise that you find a new monitoring service. I work with three.