Probe in a Fermentation Cabinet. Thermowell or no?

[yogester]

I am building a fermentation cabinet using a Zanussi fridge, a heating bar and an ATC-800.

I was wondering, from those who have done similar projects, what method of temperature measurement results in the best control of fermentation temperature:-

1. Probe inside the fridge/cabinet measuring the ambient air temperature

2. Probe inside a pint of water or something similar placed inside the cabinet

3. Probe placed in a thermowell inserted into the fermentation vessel.

I can see theoretical pros and cons of each but was wanting to know from experience which method resulted in the best control of actual fermentation temperatures.

Any insight is greatly appreciated.

Cheers!

[SiHoltye]

1) That would do the job, despite there usually being a difference between beer temperature (which is usually higher during the vigorous stage of fermentation) and ambient temperature, as long as you set the temperature accordingly, a couple of degree cooler once fermentation is underway it will be fine.

Also if you open the fridge during hot/cold weather the air temp will change very quickly to outside your desired parameters. I went for probe in wort, no thermowell. Where do you get a thermowell from for it? As the probe is flexible it coils easily into cleaning fluids for sanitising in the fridge.

By subjecting it to near boiling temps of cleaning solution am I damaging it?

[yogester]

Where do you get a thermowell from for it?

I was looking at this thermowell http://www.midwestsupplies.com/products ... rodID=7930 the other hole would be for an airlock.

BTW, what is your probe made out of? I think I got a plastic one with my ATC-800. Is yours stainless steel? I would be worried about my one in cleaning solutions.

[jubby]

I have fixed my temp probe to the side of my fridge about half way up (inside). As Chris said, there is a difference in temperature between the beer and the fridge air temp during fermentation. I have measured this difference with a digital aquarium thermometer and the beer is about 1 degree above the fridge air temp for the first day or two (during vigorous fermentation), after that the temperatures are the same. I have done this test with three brews using Safale US-05, Wyeast Ringwood and Brewlabs No9, all three had the same results. I should also mention that the ATC800 temp difference is set to 1 degree.

So the bottom line with my method is that I set the ATC 800 at 1 degree lower than my desired fermentation temperature for two days, then increase by one degree because the temperature of the beer is the same as the fridge air temp.

In my opinion, probe in the beer is the most accurate method like SiHoltye said, but I didn't want to dangle my probe in the beer (oooerrrr missus )