You don't always add or subtract 14 degrees. Depending on where you live, you add or subtract the value for your area. See the map at:
http://www.sadoun.com/Sat/Installati...Calculator.htm
I am on the west coast, so you can see the 15 that is marked in that region. So I subtract 15 from 180 making it 165. Do the same for your part of the country