I am a homeowner in New Jersey who recently had a Carrier Infinity ICS Modulating Gas Furnace (model # 58mvc) installed. In these types of furnaces the exhaust is vented outside via a PVC pipe. What about the Fresh Air Intake? My contractor has not vented it outside but left it inside. The furnace is located in my work shop area. Is this allowable or isn't it against best practices (or even code)? Case in point, by leaving it in the shop and there is a gas leak, or saw dust and other impurities get sucked in, could there be problems?