Cold Feet !
 

Any heating and air guys on this site. ?
I have a large cold air return, maybe 18"x18".
When the heater isnt on, I have a large back draft of cold air coming out.
I actually feel cold air blowing into my room.
Any ideas as to why this is doing it ? and a way to correct the problem ?
Thanks,
Hammer.

Easy - keep heater on. :part: What up Hamma?!?!?

Do you know if your unit has a fresh are intake on it? Usually in residential units the air is just sucked up from the 18" x 18" (in your case) return grill, heated or cooled and then sent out the supply vents.

Your original installer may have given you a fresh air intake as well which may be beneficial in diluting oders or if your house is one of those super efficient leak proof homes. If it is not in my opinion it is not needed so if you have one get up there and close it off with some cardboard or light sheet metal. There may even be a manual damper of sorts in it already that you can close.

If you dont have a fresh air intake, is your unit in your attic and not heated?
Could be when the heat is off the unit is cooling down in the attic and cold air is falling down your return duct.

If thats the case some type of automatic damper tied into your unit that opens and closes when the unit turns on and off may be the solution.

post some pics of what you got.

On further thought and some discussion if your unit is in an uninsulated attic you need to get up there and look for some leaks in the unit itself and any ductwork especially on the supply side up in the attic. for cold air to be coming in through that return duct you need to be losing hot air out the top somewhere.

This is what happened at my house. Ductwork in the attic had come apart.

Totally agree. In your mind think of heat as a liquid. It will always flow towards cold. That heated air, flowing out of your house, needs to be replaced with makeup air, which will flow into your home from outside. The heat flows because the body and the surroundings are attempting to reach the same temperature, at which point they are in thermal equilibrium. The spontaneous heat transfer always occurs from a region of high temperature to another region of lower temperature, as described by the second law of thermodynamics. Now, some heat is always lost through walls, windows, doors, etc., But to have a situation such as you described you need to have a hole someplace. It's probably costing you large money also, as wasted energy, so it is a good idea to locate it and seal it. I'm with RWilson on this one...look for a fresh air intake first and seal it, then look for any holes or large leaks between the heated interior of your home and the unheated exterior (including the unheated attic if you have one)

What up Brother Blue. Glad to see that ur still with the cult here. : )
Heater is in a room and not in an attic. I would seal it off, but figured the heater wouldnt work correctly.
Thinking of cutting out a vent hole in the cold air return.
Pics. rule here, so I'll post a few pics. soon.
Thanks guys.
hammer.