Does anyone know of where I can find national codes concerning to HVAC? Or is does it just concern state to state to codes? Example: I always thought it was a no no to install a heat run in a garage where combustibles and parked cars are stored that could let carbon monoxide enter into the duct system and easily be transferred into the home. Where can I find this code at? My landlord wants a heat run ran into his garage to prevent his well from freezing up. He does not want to install a garage heater but I think that is his only option. My stepdad which is a old time HVAC guy been out of commission for long time said it was okay to install heat run in garage but I am skeptical.