Newbie not getting the proof I was expecting??

[Beerswimmer]

Newbie here, I have a reflux still I bought from milehi and I didn't quite get the proof I was expecting. I had 7 gallons of DWWG that I put in and ran it at 180F in reflux and the proof came out at 164. The water hoses were cooling the tower down so much I had to turn the water way down to just more than a trickle to get the temps up. The 2x30 inch column was packed with tightly rolled copper mesh all the way to the reflux part that I left open.

What am I doing wrong here? I thought it would come out much higher than 164 proof.