I've had a fridge/freeze for years as a fermenting chamber with the help of a johnson controls brewers thermostat.It has worked wonderfully.That low temperature limit is the function of the fridge.If you require more low flexibility hook your thermostat to a chest freezer.Andy
I like to use a yeast starter just to insure i have active yeast.A cup of warm water a bit of sugar and energizer an in 20 minutes somethings going on.An old or abused yeast will tell on itself without waiting a day for bubbles.Andy