My idea for taking fermentation temps

[Munkee915]

So this is my first run on using my garage freezer as a fermentation chamber. I built a temp controller out of an stc-1000 and did a few test runs and it seemed to work well. i tested with a jug of water and placed the probe inside and let it sit overnight. checked the next morning with my thermometer and the water temps were spot on.

So after bucketing and pitching my brew yesterday i taped my probe outside the bucket and let her go. came back an hour later and when i opened the door i noticed the temp on the controller starting to spike. looked around and saw people recommended wrapping the probe in towels or something to insulate it. tried this and it seemed a bit better but got me thinking that i wanted to find the actual temps inside the bucket.

So I decided to try an experiment. I'm using a 7 gallon bucket from US Plastics which stands about 21 inches tall w/ lid. The brew comes up about 12-13 inches inside the bucket (with krausen its currently at 14). I had a 1/4 piece of copper pipe from another experiment I decided to use. I took my spare lid and drilled a hole just large enough to slide the tube through but fit snug. I cut the pipe down to about 10 inches and capped one end w/ a vacuum plug. Poked a very small hole in the plug enough to force the probe through and feed wire in but still fit snug around the wire. Feed enough wire through that the probe hangs about 5-6 in below the bottom of the tube. When I slid the tube in it fit snug but I was able to feed it all the way in up until the vacuum cap which rests around the edge of the drilled hole and prevents the tube from going all the way in. I sanitized everything then pulled the bucket out and swapped lids and put it back in.

Checked this afternoon and the temp was reading at 67F (exactly where i set it). I also had a 5 gallon bucket w/ water and starsan in there and a 1 gallon jug w/ 1 gallon jug w/ water and starsan for my blow off tube to go in to. CHecked the temps on both w/ my thermometer and they were reading at 60F. Checked the ambient temp and it read about 70F (though this was probably due to me opening the freezer door in my 85* garage).

Im guessing the higher temp in the bucket is due to activity from fermentation. It looks like this is turning out more accurate then just using a bottle or jug of water for the probe. My temps would be about 7* off otherwise. Total cost was $0 but if you had to buy the parts maybe $4 in total. My only concern was that I wasn't about to "seal" the hole and im really just relying on the snug fit and diameter of the vacuum cap up to to make some kind of seal. I thought about using aquarium silicone but I want something I can take apart as I only have the 1 probe and may need to use it somewhere else later. Guess we'll find out in a few weeks.

 

[snowveil]

Great idea in theory (basically you made a thermowell), however I'd be hesitant to use copper pipe in a finished beer.

Copper is commonly used for wort with no ill-effect but the pH drop in a finished beer is enough to cause corrosion.

You can achieve the same result (though, you'll have to buy it) with a pre-made thermowell, or you can make one yourself from a corny keg diptube which would require either capping or crimping and soldering the end shut.

However, you need to be aware that copper can develop a toxic blue-green oxide called verdigris. Verdigris includes several chemical compounds — cupric acetate, copper sulfate, cupric chloride, etc. — and these blue-green compounds should not be allowed to contact your beer or any other food item because they are readily soluble in weakly acidic solutions (like beer), and can lead to copper poisoning (i.e., nausea, vomiting). To clean heavy oxidation (black) and verdigris, use vinegar or oxalic acid-based cleansers like Revereware Copper and Stainless Steel cleanser.

-John Palmer

 

[Munkee915]

Thanks, I didnt know this. I went back this morning and pulled the tube. I can see where the copper was nice and shiny where it made contact with the beer. I cut another 6 inches or so off the pipe and sanitized again and put it back. It now sits about 2-3 inches above the krausen and the probe falls into the beer itself. The original idea wasnt for the copper to act as a thermowell but really as a channel to slip the probe in and it sit in the beer. The beer is still in the first 48 hours of fermentation so hopefully this doesnt affect it too much. Ideally I would like to use a stainless tube but I just used what I had on hand at the time.

 

[snowveil]

Sounds like a plan!

So many folks get by with just putting their probe onto the side of the carboy but I swear by getting the probe into the beer itself. Thermowells are relatively cheap when you look at the total cost of fermentation chambers, fridges, heating elements, and thermostats.