PEABODY – An elderly man was found dead inside his home on Felton Street Sunday as the result of a furnace explosion, according to officials.Joseph Andrade, 86, was discovered unresponsive inside the soot-filled home by a family member during the afternoon. When police and fire officials arrived on scene, they say high levels of fumes and soot led them to focus on the heating system, which they say appeared to have had some type of malfunction.It is not clear whether Andrade had smoke alarms or carbon monoxide detectors in his home, where he lived alone.While officials did not say what type of fuel was used in the furnace, or the age of the device, Bob Walsh of Walsh?s Oil in Lynn said all systems need to be routinely checked in order to prevent problems like this from occurring.?It?s kind of like not going to the dentist,” he said. “Good preventative maintenance is key and well worth it.”Walsh, who was not affiliated with the explosion, said the incident could have been the result of a delayed ignition in the furnace, where a mini-explosion can occur, sending soot flowing through the blower and into the home.?On most systems, there are a lot of safety measures and tell-tale signs, so something should have gone off to alert him,” he said. “But with the elderly, some are on their game and some aren?t, so he might not have heard anything to let him know something was wrong.”The incident is being investigated by State and Peabody police, the State Fire Marshal?s Office and Peabody Fire Department Investigators.Several officers were treated and released at Lahey North Hospital for exposure to the poor air conditions. Foul play is not suspected.