That HVAC guy's tip about hiding sensors behind ductwork backfired hard

So a few months back, I was working a big commercial install over at the old strip mall on 5th street. Ran into this veteran HVAC tech named Carl who told me I could save time by mounting motion sensors right behind the return air ducts. He said the air flow would help with false triggers and hide the wiring. I figured the guy had been doing this for 20 years so what could go wrong. Well those three sensors I put behind the ducts kept tripping every time the AC kicked on around 2 PM. After two service call backs and a frustrated manager, I finally ripped them out and moved them 4 feet to the left on the bare wall. Works perfect now. Has anyone else gotten bad advice from cross-trade guys on site?

2 comments

2 Comments

paul3305d ago

Always thought cross-trade guys had the best shortcuts since they see so many different setups. But after trying that duct trick myself last year on a job, I totally get why it backfired. The air pressure changes mess with the sensor's field of view every time the system cycles. Carl probably meant well but that advice was just wrong for modern sensors. Glad you caught it after only two callbacks instead of wasting more time like I did. Straight wall mounts are boring but they actually work.

thompson.tyler2d ago

Ngl that line about "straight wall mounts are boring but they actually work" hit me hard @paul330. I've been in that exact spot where you chase some trick that's supposed to save time and it ends up costing you way more in the long run. Carl probably learned that trick back when sensors were less sensitive or something, but with the newer high sensitivity units, even a slight breeze from a duct will set them off. Solid reminder that sometimes the standard way of doing things exists for a reason, even if it's not flashy.