[Titan151]

The amount of cooling produced by a pelt is directly related by the amount of cooling you apply to the hot side of the pelt. That said, air cooling the hot side (not sure if this is how you are doing it) will do little provided the air temps are 30+ C. You could consider using a second water cooling system to cool the pelt, but when this is all said and done, it would be easier to simply build a chiller using two separate loops (one to cool the hot side of the pelt and one to cool the water from your main loop).

I have seen somewhat similar things tried by others with limited results. There was someone who built an air cooled pelt and submerged the cold side into a reservoir. I think the end result was only 1-2 degrees of additional cooling.

It might be easier to port the cool air from an air conditioner into the radiator. You can pick up one of these for around 70 US if you look around. If that doesn't work out you can always mod the AC unit into a water chiller.