Venting hot air to cold air return?

[Smokin Joe]

thanks a fortune. i'm going to add you to my friends list, you have been extremely helpful.
the vents are all in the ceiling. the house is 25 years old. i've been here since late 2007. the owner had allergy problems, but i think moved out around 2005 and started renting it out. its got an air purification system, im not sure what it does but its a small powered box with some wires going in the part of the AC in the garage. sorry for my ignorance on part names. that unit was installed in 1996, so its a bit newer than my compressor.
i've been using the best filters, i think the filtrete 1900 or whatever the top one is. but before me, who knows.

You are probably okay as far as the duct cleaning goes. Sounds like a uv light in your unit. They help a bunch.

Gala, great info posted here.

So rearranged my ventilation last night.

One thing I noticed before I hooked the exhaust to my cold air return was that with my previous set up of tent in a room venting into the attic is that the pressure from my fan was ripping cold air thru my return vent, which Im thinking could have had a very negative effect on my heating system. Im thinking with the suction in the room it was probably causing so return air from my second floor to properly get back to the heating system.

Gala, after your last post I went thru and vacuumed out my floor vents, I sent the vacuum hose in as far as it would reach and I couldn't believe how much crap had accumulated in my ducts

Always happy to help