Air filter inside the return

[Kalont]

Several years ago I had my HVAC system replaced and a contractor decided to make a custom (diagonal) opening in the return, right before it enters the system cabinet, so I can slide in air filters instead of changing them inside the unit.

Is there a problem with air filter sitting inside the return or this is a common practice?

Thanks

 

[Silentrunning]

There are really only three things to look for regarding the filter. 1. It captures 100% of the air flow. 2. It is properly supported and can’t be sucked into the mechanism. 3. It doesn’t restrict the air flow. I also would make sure that the opening your service man cut is completely sealed after inserting the filter. You don’t want are getting sucked into the opening.

Oh yes, welcome to the forum.