Hi Went to a house today and found a disc limit switch factory mounted on a venter motor. It had kicked out. I took a temp reading after I reset it and it only got about 112 degrees behind the disc. What is the real purpose of a limit on the ID fan. Also is it any indication at all of a cracked heat xchr. The unit ran perfectly after I reset it. The customer says he had to reset it about 3 times in the last 2 years, and like 4 times in the last week. Probably just a weak sw. But I don't know why they put these discs here. The flue gas was at normal temp and the CO reading at the exhaust was 19 ppm.
Kinda funny but he had a bad hose connected to the pressure switch from the ID fan and took a McDonalds straw and inserted it into the tube and onto the Pressure switch. I obviously fixed it. I cant see that being a problem could it. The switch opened and closed fine. Not sure if it really would have anything to do with the limit kicking out. Thanks for any info