55-gal., drum cold smoker..draft/ventilation...from total newbie

IMO, you need about 2-3 times the exhaust opening that there is on the inlet...    The air inside the smoker expands with heat, and to eliminate condensate, you need good air flow and the smoker temp must be above ambient....

Serious air flow is needed during the cold smoking process to eliminate moisture....

http://www.meatsandsausages.com/meat-smoking/cold-smoking
[h1]Cold Smoking[/h1]
Cold smoking at 52-71° F (12-22° C), from 1-14 days, applying thin smoke with occasional breaks in between, is one of the oldest preservation methods. We cannot produce cold smoke if the outside temperature is 90° F (32° C), unless we can cool it down, which is what some industrial smokers do. Cold smoking is a drying process whose purpose is to remove moisture thus preserving a product.

You will find that different sources provide different temperatures for cold smoking. In European countries where most of the cold smoking is done, the upper temperature is accepted as 86° F (30° C). The majority of Russian, Polish and German meat technology books call for 71° F (22° C), some books ask for 77° F (25° C). Fish starts to cook at 85° F (29.4° C) and if you want to make delicious cold smoked salmon that is smoked for a long time, obviously you can not exceed 86° F (30° C). Cold smoking assures us of total smoke penetration inside of the meat. The loss of moisture also is uniform in all areas and the total weight loss falls within 5-20% depending largely on the smoking time. Cold smoking is not a continuous process, it is stopped (no smoke) a few times to allow fresh air into the smoker.