Hello guys I have a question concerning installing a cold air return in the basement. I had a HVAC company come to my house and told me the following, taught I would share with you all and maybe get some input on the situation.
He said DO NOT put any returns in the basement, it is acceptable to open up some supply registry to get some warm air blowing into the basement use a fan to circulate the air but no returns. His response was that he use to put returns in the basement and it works to balance out the pressures but soon realized it did not work the same for every house due to their basement layout and in some cased it lowered the air pressure in the basement causing things such as back draft, increased humidity in the home, excess condensation which all seems to go away when the return was closed off.
His advise was to be on the safe side and just open up some warm air registry to blow air down and use fans to circulate the air instead of installing a cold air return, he also advised that it is better to have a slightly positive pressure in the basement than a negative pressure.
Another thing he mentioned that I would like to discussed was that the only way I can have a cold air return in the basement was if I put a 5" dia insulated flex duct from the outside (fresh air intake) and bring it into the basement and loop it up like a "U" this way fresh air is introduced, will balance out the pressures and the cold air return can circulate fresh air through out the house. He also advise do not put the flex duct directly into the cold air return because he has seen frost developed in the inside of walls and he showed me some pictures as well it is never a good idea to have -30 deg C temp passing over your furnace the best was was to do the "U" loop thing and let the cold air return pick it up.
I don't know if that all makes sense just taught I would mention it and get some feedback.