UPDATE: Jan 15-The State Fire Marshal's office said that a problem with propane caused yesterday’s house explosion and fire in Union.  Fire Investigators say two portable propane heaters had been installed in the house during renovations and a problem with either the heaters or the gas line caused a buildup of propane inside the building that ignited.  The two story farmhouse was leveled. The occupants of the house had been staying elsewhere because of the renovations, according to Maine Department of Public Safety Spokesman Steve McCausland