Im not exact on the size of my Sear chest freezer, except when I got it in 1993 it was the biggest they sold(24 or 26 cuft, and barely fit thru the door into the house, I got the manual defrost button, which only takes minutes to clean, once you open the lid and pull the button out, by the time you get all the frozen stuff out, the ice falls to the bottom, scoop it out, wipe it down, replace your food, close the lid and it resets.....simple as that.....
I also got the "QuikFreeze" selection, it runs the compressor for 24hrs to quickly freeze room temp items....and the "TempMonitor", in case the door is left open, or the power goes out, and the temp goes too low(battery backup for the alarm)
I also have a 20 cuft upright freezer...MANUAL Defrost......never again......takes a long time to defrost and melt the ice build up.....and the floor flooded mess....which has to be done about every 6 months.........
Food for thought.......NEVER have your freezer plugged into a ground fault outlet......we had a power outtage which only lasted a few hours, when power returned, it "popped" the outlet.....this upright does not have the battery backup alarm for low temps.....3 days later opened the door to a major mess of all the foods ruined and landslide across the floor.......that outlet has been replaced with a regular one....