I just got a 20 plate chiller. Used it for the first time today and I must be doing something wrong since my wort only cooled to 84 and I used a pre chiller ice bath with 25' of copper tubing. My old immersion chiller of 50' did better than this. I had to put my wort in my mini fridge for hours to get it down to pitching temp. I thought this was supposed to be my cure to summertime wort chilling....................... What did I do wrong?