Draft pressure switch for Trane and American Standard gas furnace applications. The draft pressure switch is designed to prove to the main control board that the draft inducer is operating correctly and you have the proper amount of air for combustion. This switch should always be replaced with the factory recommended part. If the switch chosen for your do it yourself repair is not correct there could be a safety issue. Please contact us with your model number and we will be happy to verify you are ordering the correct part. The switch for your model is designed to open and close at a specific draft pressure that is matched to your furnace.