immersion chiller/heater

[andycook]

Using spare aquarium pieces and a carboy I'm experimenting with a DIY fermentation chiller/heater.

I have a plastic widemouth carboy. I drilled a hole in the side and mounted a coolworks ice probe chiller. This unit is usually good for cooling up to 50 gallons a few degrees.

Heating is a 50w titanium aquarium heater. Right now the cord is fed through the top of the carboy wide mouth top. I would probably mount the heater on the bottom of the carboy.

The heater and chiller are controlled by an inkbird controller. I have the temp set to 65*F and the alarms at 60 and 70*F respectively.

One design aspect I haven't tackled yet are the wires coming out the top. I assume I'll drill another hole near the top on the side or even on the lid and feed the wires through that and seal it up.

In my test run with 5-6 gallons water. 1) the thin carboy plastic walls make it a constant battle against the air temp which is 6 degrees higher than my set point. 2) with no movement (like fermentation) the water temp varies by a couple of degrees in layers with the bottom near the temp probe being at my target and the top being several degrees warmer. 3) i haven't seen the heater kick in due to the air conditioning. 4) if this were an aquarium i would drop a small circulation pump in to keep the water mixed.

I'll try this on what ever I brew next but at this point the biggest gain seems to be the temp probe giving me readings from inside the carboy.

 

[kh54s10]

It looks interesting. Nice project. Maybe you could circulate with a pump from the spigot and return to the top with a piece of tubing submerged so there is no splashing.

I ferment in my basement which is about 70 degrees year round. So I am cooling only, year round. I use a chest freezer for lagers and a fermentation chamber (minifridge in the end of a homemade insulated box) for ales. If I wanted the probe in the vessel I would just get a thermowell. Personally, I wouldn't sleep well with all those fittings in my fermenter. I don't even like spigots.

 

[andycook]

Thanks for your input. Year round my basement varies from ~62*F to 74*F depending on how long the lights are left on.

I assume that active fermentation will be enough to keep the inside churning and I won't have temperature zoning and won't need a circulation pump.

However, the idea of an internal circulation pump makes me wonder if there would be any benefit from whirlpooling so the sediment/hops is in a pile in the center.

I can see why the insulated carboy covers are beneficial to holding temps.

 

[andycook]

Testing this out with an oatmeal stout I brewed yesterday. I am a bit concerned that I did not get an airtight seal around the wires coming through the top. I suppose I could caulk or silicone. In the future I would run them through an airlock probably made out of pvc to fit the wires.

Pitched yeast at 77*. About 6 hours later the chiller had it down to 76*. This morning the temp was 68*. There was a nice krausen on top. I suspect the yeast moving around during fermentation is actually helping cool the wort by keeping the wort churning and thereby exposed to the chiller. Ultimately I'm shooting for 65*, the mid point between the low and high for my yeast.

One question I have is - how often will I really need the internal heater? Maybe in the winter. The basement can drop to 62*.

 

[mongoose33]

<interesting experiment>

Two questions I have: One is whether it might make more sense to use a Fermwrap heater to do that--it can be wrapped around the outside and thus no compromise of the sanitation.

Second is how you're cleaning the aquarium heater. That looks to me like a significant potential source of infection, which would be utterly mitigated by using an external heater.

The same question is posed for the temp probe. I have mine on the outside of the fermenter (I use the same BMB, btw), using a piece of foam to insulate it from ambient temperature:



I've been pondering this stuff as well, and appreciate your willingness to do some experimenting and report on it. I have a fermentation chamber (refrigerator) but it won't be as useful if I have a lager going at 50 degrees and want to do an ale at 65 degrees, so a separate system would be useful.

 

[andycook]

Thanks Mongoose33.

Have you or anyone done any testing to see how much difference there is between internal vs external temps? I assume it is small and can be calibrated into the controller settings.

Does the heater kick on for you? I begin to have doubts about needing it all. Basically I had these parts on hand so I used them. Ultimately I may end up sticking a heating pad up under the t-shirt I used to keep the carboy in the dark. Though the fermwarp heater does look interesting.

The aquarium heater is a titanium rod with a wire out the top. I'll have to be careful with cleaning to be sure but I don't anticipate any trouble cleaning it or the chiller.

I think the thermowell is a good idea too from a prior post.

My biggest worry has come true. I don't have a seal where the wires go in at the top. This is a test batch but still i want to make beer so I'll pull it out of the primary as soon as fermentation stops. Right now inside the carboy looks like a sea monkey lava lamp and there is a good thick krausen layer so I'll probably be ok.

I am rather excited to be in control of the fermentation temps. I figure my prior batches probably ran 72-82*F depending on the season and the lights in the room.

-Andy

 

[mongoose33]

Thanks Mongoose33.

Have you or anyone done any testing to see how much difference there is between internal vs external temps? I assume it is small and can be calibrated into the controller settings.

The difference is minor if at all. I don't worry about it, and I'm pretty anal about a lot of things.

Does the heater kick on for you? I begin to have doubts about needing it all. Basically I had these parts on hand so I used them. Ultimately I may end up sticking a heating pad up under the t-shirt I used to keep the carboy in the dark. Though the fermwarp heater does look interesting.

I think there are many ways to heat these fementers, from a fermwrap to a heating pad to a ceramic heater to even a light bulb on the outside of a box encasing the fermenter. The Fermwrap works fine but it's not the only way.

I use an Inkbird 308 to control these things, but so far I tend to have the refrigerator in an environment where either heat or cool is needed, but not both. I have a fermenter going in the fridge right now, the Inkbird keeps it at 40 degrees with a 1-degree differential.

The aquarium heater is a titanium rod with a wire out the top. I'll have to be careful with cleaning to be sure but I don't anticipate any trouble cleaning it or the chiller.

Are you going to use something like PBW? I see all sorts of crevices such as around the suction cups or cord that stuff could hide.

I think the thermowell is a good idea too from a prior post.

Several times I've come close to buying one but for whatever reason can't pull the trigger. I guess it's because the foam approach above seems to work fine.

My biggest worry has come true. I don't have a seal where the wires go in at the top. This is a test batch but still i want to make beer so I'll pull it out of the primary as soon as fermentation stops. Right now inside the carboy looks like a sea monkey lava lamp and there is a good thick krausen layer so I'll probably be ok.

As long as there's active fermentation you'll be producing CO2 which will keep a positive pressure inside. I've got a fermentation going right now, same thing inside. I like the sea monkey reference.

I am rather excited to be in control of the fermentation temps. I figure my prior batches probably ran 72-82*F depending on the season and the lights in the room.

-Andy

I'm fortunate because my basement allows an ambient fermenter temp of 65 degrees. When fermentation is going at it, it'll rise to 69 or so, unless I use a swamp cooler, then it keep sit closer to 65.

 

[andycook]

With the chiller I am using I noticed that the first degree decrease in temp took over 12 hours (probably due to the lack of circulation). The next 8 degree decrease in temp took about 12 hours (circulation once fermentation kicked in). The last degree decrease is at the 24 hour mark and working (the seamonkeys are still moving around carboy.)

How much heat is added by fermentation? I didn't imagine that the chiller would run constantly through fermentation, though the basement temp ranges 73-75*F at this time of year. The chiller can drop ~50g of water 1-3*F so a 5g batch should be in reach.

 

[mongoose33]

I've tended to get about 5 degrees or so--but it may be different with the robustness of the yeast. I've used S-04, S-05, 2112, 980, and 1028 and they were all about the same. A slower yeast would, I'm guessing, produce less heat. S-04 is pretty fast--I pitched some (rehydrated) on Sunday, was going Sunday night, going nuts on Monday night, but by late Tuesday evening it had slowed down.

 

[rodgers]

Very cool stuff. I've been thinking long and hard on immersion chillers for a long time and really hope this experiment works out for you.

 

[andycook]

Next go round I think I'll see about insulating the carboy. Right now it is covered in a t shirt just to keep the light out.

 

[andycook]

I've put about 4 batches through this setup. Several are bottle conditioning now so I'll know in a couple of weeks how the beer made this way tastes.

I did buy one of those thermowell-stopper combos to try on my next batch.