Regulating temps in chest freezer

I have read many posts on here inregards to this and I still don't have an answer. Here is my set-up: LOVE TSS2-2100 temp control in a 14 cu ft chest freezer. It is set up or both cooling (freezer) and heat (not set-up yet and ideas needed). The controller is set for the freezer to kick on at 70 degrees. Right now I want the fermenter to stay at or near 70 (later it may be 65, etc). So the freezer kicks on, but the problem is that it drops all the way down to 64 before it begins the climb back to 70. To me this is a pretty big variation in temps. Am I wrong on this? How to I get it to stay near my desired temp? I thought I could do it without some kind of heating element, but maybe I was wrong. Any and all help is appreciated. Thank you in advance.

Mike

Do you mean the air temperature is swinging between 64 & 70 in an empty freezer? If so, put in a jug of water and see where the temperature of the liquid is after it's been in there for few hours. A fan inside will help move the air around too. It's been discussed here in many areas, so you'll probably find more ideas with a little searching...

Chest freezers will always over-shoot the set temperatures. This is because once it hits the desired temperature there is still unevaporated refrigerant in the coils, which will evaporate and cause more cooling. If there is little or nothing in the chest, the temperature over-shoot will be large. A full freezer will be much more stable.

Thanks for the replies. I appreciate the info.

david_42 said:

Chest freezers will always over-shoot the set temperatures. This is because once it hits the desired temperature there is still unevaporated refrigerant in the coils, which will evaporate and cause more cooling. If there is little or nothing in the chest, the temperature over-shoot will be large. A full freezer will be much more stable.

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Unless your using a Johnson A419 controller. Mine is always 67-68. Having more control over your temps as well as the option to cut in or cut out is nice. I spent over a month researching fermentation chambers and temp controllers.

Just put my first batch into my stc 1000 controlled chest freezer. The dry run w a glass of water had me worried about the overshooting thing, but now that I've got some thermal mass in there the temp is very stable. I hooked up a simple lamp on the hot side, but might upgrade to a personal heater.

Where do you have your temp probe?

The probe is hanging down off the lid.

For the best control of the beer temp you want the probe attached to the fermentor. I have mine attached to the outside with a piece of styrofoam over it to insulate it. This will give you a pretty accurate reading of your beer temp. right now you are metering air temps which can be very different from the temp of your fermenting beer.