Those airlocks have been known to block up. Often the opening that goes into the fermenter gromet are quite small, then all you need is a bit of hop leaf and they are plugged.
Had a friend who came home, found the base bulged on his fermenter, pulled the airlock out and the pressure meant his ceiling was sprayed. He then had to go find a ladder so he could wash the ceiling. This was at 11pm at night. The joys of homebrewing.
Like the others said, get the right sized tube and fit a blowoff. A bucket with a bit of water and a dash of bleach works wonders. Even easier than a jug. Try and clean the lid up with paper towel dipped in the bleach/water. In theory none of that gunk gets back into the fermenter, but it does make a lovely feast for any bugs hanging around, and then when you are opening or closing the lid, the chances of some transferring does increase.
If your end room is about 16 deg, grab yourself some yeast that works at that range, for example some Saf-05. That way, you are working with your yeast rather than struggling to maintain a warmer or cooler spot.
Like the others have said, throw those kit instructions away. Any kit will be better for fermenting at 18-20 degrees.