Update: spent 40 minutes chasing a zone fault in a customer's attic when the foil tape on a duct was the whole problem | Alarm System Installers - Topic Shares
Update: spent 40 minutes chasing a zone fault in a customer's attic when the foil tape on a duct was the whole problem
Last Tuesday I was up in this attic in Mesa trying to figure out why zone 3 kept showing a fault on the panel after I swapped the sensor twice. I kept checking the resistor crimps, reseated the terminal screws, even ran a fresh wire to the can, and nothing changed. Then I happened to look up and saw a strip of foil tape on the HVAC duct about 8 inches from the sensor, and it was just close enough to trip the magnet in the reed switch every time the blower kicked on. I pulled the tape, put a small piece of foam between the duct and the sensor, and the zone held clean for the whole week since. What gets me is the homeowner had a tech out 6 months ago for the same issue and he just replaced the battery and left. Has anyone else run into foil tape or duct work messing with a reed switch, or am I just lucky this one was easy to spot?
Tbh foil tape on ducts has burned me more than once, that stuff plus metal ductwork can throw a reed switch off from a few inches away. The fix is usually what you did, keep the magnet off the metal or shim the sensor so the duct field does not mess with it. That last tech just swapping the battery was lazy, the sensor was telling him something and he did not listen.