Temperature control help

I just came by a free chest freezer and I want to set up a fermentation chamber. I know JZ uses a dual stage set-up with a fermwrap-ed carboy inside a chest freezer. I guess I have two questions:

1. Is it really necessary to have both a heating and cooling element at work? Wouldn't it be enough to have a digital temp control on the chest freezer as long as the ambient air temp is higher than my desired temp?

2. If I do go the route of having a heating element and a cooling element in place, would I be better off getting two separate single device controllers, like the johnson a419, or is there an advantage to having one of the Ranco controllers that can run two devices at once?

It seems more versatile to me to have two separate units, but I didn't know if having both in one had more applications that I might want to use later, like setting up a RIMS or something like that.

Thanks!

When I got my freezer I bought a single-stage Johnson 419 and wired it up just for cooling. In hindsight, I would have bought the dual-stage so I can lager in the winter being my garage can get into the 30s and 40s at times. I put a thermometer inside the cooler to monitor the difference in ambient temp inside the freezer and outside in my garage. I found my controller on ebay for 50 bucks with shipping, so I may end up being better off as the dual stages are all above 100. If I can luck out and find another single stage that is in that price range I will end up with two separate controllers, but will only have to run both in the winter. The only reason you'd need a dual stage or two controllers is if the ambient temp. inside your freezer gets lower than your desired ferm. temps.

Not hijack this thread but... Is there a way that I can use two controllers at the same time without the heating unit and the freezer fighting each other?
I have a Ranco digital controller with a 1 drew differential and a Johnson A19AAT-1 that has a 2 degree differential.
How would I set them so the the heat and cool are not on at the same time?

^
You would need to set one of the units to heating mode, of course, with the other in cooling mode. You would want to set their set-points a degree or more apart so they don't conspire to jack your electric bill. For sure, before you turn the works loose, you would want to check the temperature readings from the two controllers with the probes in virtual contact, take note of any offset, and factor that into your set-points.

And the differential on both units is adjustable, so that's pretty much a non-issue...

Cheers!

Alsace,
If you decide to go with an STC-1000 (Ebay/Amazon) build, pay close attention to the polarity of your power. I used a modern three wire molded cable from a spare computer and the wire colors are not marked . The large blade on the left side of an outlet as viewed from the front with the round terminal facing down is the Positive. The right blade is the neutral and the round post is earth ground. If you dont follow the correct polarity you will not get your controller to work properly. So take your time and follow Revvy's diagram with close attention to matching the right wire to the right blades and you wil do just fine. I am CHEAP, so I bought the Ebay unit and made sure I got the 115 VAC model and built the set up in a new work 2 outlet box. (The blue kind). I have less than 20 bucks in my controller and it works exceptionally well with low overun and programmable temps for heat and cool. Set the temp, set the spread, set the compressor timer and walk away!!! I am also a computer simpleton and I figured out how to program it even with the Chinese instruction manual......

Wheelchair Bob

Def do the STC-1000. I had alot of reservations at first but after doing it, it was soo damn easy. Plus the heating element gives u the ability to ramp up the heat for diacetyl rests and also saisons. Plus, at least for me, my garage gets uber cold in the winter, so i can do ales in the winter and lagers in the summer.

I just use a single stage for cooling only. In Texas, I rarely have to worry about my beer getting too cold...