Frame feeders can be used for cold weather feeding with the least
possible hive disturbance.  Place the frame feeder at the end.  Drill a
1/2" dia. (or so) hole in the inner cover directly over the feeder.  Now
to feed, slide the top cover over about 3" to uncover the hole, stick a
small funnel in the hole, and pour in the syrup.  The seal on the top
cover is never broken.
 
Check the syrup level by using a dipstick through the hole.
 
I have found the manufactured, plastic feeders unsuitable.  I make my
own which are larger since the feeder goes all the way to the inner
wall.  For a shallow super, my feeders hold just under 2 qts. ea.; for a
deep, one will hold about 3 1/2 qts.
 
For my food supers, I leave a feeder permanently in place.
 
While I would not consider this method suitable for a commercial
operation, it works well for me.
 
Burns
NE PA 76W 41 1/2N