Quote Originally Posted by martin82531 View Post
The hydrofarm shuts off at 91 degrees which is what I have it set to, I think its just the "left over heat" from my UTH that admits and that gets the temp close to 93 degrees before the temp actually starts to drop.
That's pretty much what it is. The on/off type of thermostat is running 100% until it reaches the desired temp, then turns off completely. what you are getting is the residual heat from the unit cooling down. Proportional thermostats actually lower and raise the amount of power needed to maintain a constant desired temp, so they are much more accurate.

Honestly, the variation isn't so much that you need to worry. However, i would keep a good digital thermometer nearby, and check your warm end once in a while.

For me, at this point in time, a 1 or 2 degree variation was worth saving the 85$ difference i would have paid for a proportional thermostat. Now once i get into breeding, i'll go all out and spend the big bucks and get a top of the line thermostat.