Temp Controller Question

I have a 5 CF Freezer I bought for a fermentation chamber and ordered a RANCO temp controller.

Stupid question but in terms of actually using this set up. How do I put the probe into the freezer, just toss it in and close the lid, or do I need to cut a hole through the lining and run it through?

 

I use a Ranco and didn't run it through the chassis or door. I just put the probe inside (in the air, not in a cup of water, although I may change that) and closed the door. Works just fine. I've checked the inside temps with other thermometers and it is accurate. Not the cleanest setup, but the easiest, and it works.

 

Hi

Anchor the probe down to *something*. Having it hang in air is not a real good idea.

Bob

 

Agreed, mine is attached inside. I meant more to say that it is interfacing with air vs. water.

 

There are many stories of people burning up their brand new freezer's compressor in a few hours using a Ranco with the probe hanging in air in an empty freezer. The big issue with Rancos is the lack of ASD protection, at least the ones I have seen. You need to have the probe on/in something thermally massive to shield it from sudden ambient changes which could cause a 'hot start' that can almost instantly kill your compressor. I think the Ranco probes may be a bit slower responding than other probes, but it still isn't worth risking burning up a compressor.

For fermenting, placing the probe on/in the ferm vessel is the most popular, and least problematic, probe placement. Strapping, then insulating, the probe to the side of the ferm vessel is the reigning king of probe placement. There are a lot of fancy write ups on it if you want verification; or if it just makes sense, like it does to most, you can just run with it.

When you do not have anything in the fermenter, or even when you do, put some additional passive thermal mass in there, and switch the probe to one when not ferming. If you prechill the passive mass to ferm temps, you get better control, especially with a fan.

 

So, for fermentation, you have your probe attached to some part of the freezer?
The coincidence of both you and carlisle_bob (who also advocates taping the probe to the cooling coils/wall) being in the same thread is long enough odds. If you also use this method for fermenting, they are off the charts.

 

To add to what cwi said, there have been several reports of the ranco probes not holding up to being submerged for prolonged periods. Instead of submerging the probe in a cup/bottle/yeast vial of water, I'd suggest taping it to a bottle/container of water.

 

It is electrical taped to the side wall. Nothing fancy at all.

 

I used some bubble wrap folded and taped to the side of the carboy. Then placed the probe between the carboy and bubble wrap. very solid temps this way.

 

For fermentation I suggest getting a thermowell with stopper and placing the probe in that. That way the probe is not truly submerged but will get you the most accurate reading of the liquid temp.

While I am using my temp controller to heat as opposed to cool, this method seems to work fantastic.

 

That method makes it very difficult to maintain any kind of temperature stability of fermenting beer. It doesn't even work very well for kegerators. Active fermentations are commonly ~10F higher than ambient air temps, but it varies during the course.

You do realize that the walls of a chest freezer have freon running through them that gets very cold (<-20F), and depending on the location, very fast- ~20 seconds for mine. If you are using a fridge, taping the probe to the wall is less of an issue for short cycling, but it can be catastrophic for a chest freezer using a Ranco due to its lack of ASD to prevent hot starts/short cycling which can fry a compressor in < 1 hour, and has.

Even with a fridge, there is still the issue of opening the door shortly after a cycle, which can cause a hot start, especially with a Ranco.

Contrary to politically correctness, and parents who won't tell their kids NO, there actually is a wrong way to do things.

 

Interestingly, there have more than a few tests using a thermowell, and the results showed that affixing the probe to the wall of the ferm vessel, then placing insulation over it, provided better temp control than using a thermowell (at least for homebrew type setups).

It has to do with the ambient air in the ferm chamber slightly influencing the probe, to provide both early cut on, and early cut off. During later ferm stages, the issue with the thermowell was significant radial stratification. The outer layers of the quasi-static liquid would chill well below the setpoint before the thermowell hit its setpoint.

 

cwi is absolutely correct on both counts. The wall of a chest freezer is one of the worst locations for a temp controller probe, giving you terrible temp control accuracy, and needlessly increasing the compressor cycling. Thermowells on the other hand don't present any major issues or risks, but there are cheaper and easier ways to do it that will provide better results.

 

Perhaps I've been lucky things have worked so far. But it looks like I need to adjust my method. Thanks for all of the good tips guys!