Why does nobody talk about how bad the seal is on those generic HVAC filter grilles?

I keep seeing people install those cheap stamped steel filter grilles from the big box stores and they leave a quarter inch gap around the edges. Air just goes right around the filter instead of through it. I tested it at my own house with a smoke pencil last month and the difference was crazy. Half the dust in your ducts is probably from the filter not actually filtering. Does anyone else bother to add foam tape or just let it slide?

2 comments

2 Comments

elliotjenkins9d ago

Honestly I read somewhere that this exact issue causes like 30% of residential HVAC problems because people just assume the filter is doing its job when it's really not. The smoke test you did is exactly what I saw in a YouTube video from an old school HVAC guy, he showed how even a small gap makes the whole system useless for filtration. Ngl I always add foam tape now on my own grille, it takes two minutes and seals it completely. Tbh most people probably don't even think about it, they just slap the filter in and call it done. But once you see the difference with a smoke pencil you can't unsee it.

victorbutler9d ago

Bro the smoke pencil trick blew my mind too lol. I tried it on my own unit last month with a cheap vape pen and saw dust shooting through a tiny gap in like two seconds. Foam tape is so cheap and it takes almost no effort, I honestly don't get why builders don't just include it from the factory.