Air Return Plenum Concerns.

[flash8]

Hi, had a question about the return air "box" that my Trane XE 80 sits on. The system is located in my garage along side a water heater. I live in Arizona.(Dusty) The construction of this "box" is OSB ,drywall and a concrete floor. While changing the filter I wondered if this area was a poor design and was allowing dirt/contaminants into my home. My family suffers from allergies and I am constantly keeping filters changed and. ducts cleaned. Should is area be sealed and made of metal or some type of * I was thinking of purchasing one of those Aircycler controllers to use the system to filter the inside air for periods during the day. I am concerned that this plenum could is cleaner and better constructed. Any ideas or input is appreciated.

Thanks,

Flash8

[Freon]

I assume you have return ducting coming from the house to this plenum. As long as all seams are sealed and the return ducting is tight, there should be no dust infiltration. If you're worried about vapors from the OSB you might consider painting that surface to seal it. You might paint the drywall part also. Otherwise I wouldn't worry. Be careful of a too restrictive filter since adequate air flow through the system is critical.

[flash8]

Thanks, the return does go to this area. I currently am using a 1in 3M 1200 filter , would a thicker filter be too * I appreciate the response I'm going to paint the area just to seal the OSB and concrete. Any thoughts on the aircylcer for recirculating air through the *

[Freon]

I can't say if that filter would be too restrictive. But here is how you can determine it for yourself. First, feel the supply vents (air out) at all the rooms. If you feel good air flow, that's a positive. Next, and most important. go to the furnace and watch it run a complete heating cycle. What you are trying to determine is while the blower is running and circulating hot air in the house, do the burners cycle on and *

If the burners stay constantly on during a complete heating cycle, that's a positive. If they cycle it means the high temperature safety limit switch is shutting off the burners because the heat exchanger is too hot due to lack of adequate air flow through the heat exchanger... the filter is too restrictive OR there is some other restriction in the duct system.

As for circulating air when not heating or cooling, you can buy thermostats that allow for programmable intermittent fan operation... on X minutes, off Y minutes.