My mother of a fermentation chiller

I'm still not a brewer, but I'm preparing myself to do my first batch soon enough. However, this summer, when I began to think about what I needed to do (after reading Papazian's and Palmer's book), I read that it was important to ferment at the good temperature. This brought to me many questions and complications due to my limited space (I'm in an appartment with my gf) and due to my hands' agility limitation (I'm really _not_ a handyman). I'm in Montreal and, as it is humid here, there's no swamp cooler. With that in mind, I posted a thread here ; https://www.homebrewtalk.com/f39/temperature-129115/

OK, in Montreal, the winter is cool, but as I'm in a big building and there's some old people here, the heat is set very high for the entire building. And my only space to put my cooler in is a small closet far away from a window... So, I need some kind of temperature control.

I continued to read on this board, and I've stumbled upon the Son of a Fermentation Chiller / Mother of a fermentation chiller. Now, these things seemed perfect to me. It's a very aesthetic solution as I didn't like the idea of having lot of water to cool with ice... it's a lot of hassle for no precision in temperature control, although very cheap. And I didn't find igloo cooler anywhere near my apartment.

However, I'm kind of a anti-handyman. My father was of the school of thinking that it could hurt me, so he never let me use his tools whenever he was working. And, well... I'm more of a theorist than a manual kind of guy, I have always been very poor using my hands. Yesterday, I managed to destroy an Ikea furniture my gf bought while trying to build it...

But I was willing to learn as the thing seemed about right. I wanted to have a nice wooden thing with insulation foam in it's interior. With wheels to move it around in my apartment... So, one of my friend, who is a lot more of a handyman than me (hell, he helped his dad to build extensions to his house, built many other things and like to work with his hands) accepted to help me. But, he was here to _help_ me, not do all the work himself.

We didn't have any specialized tool like a saw here. Only basic stuff and a drill he brought. We asked the hardware store to cut the plywood sheet the good size for us. They were the right size, right, but... they weren't straight. So the fermentation chiller isn't perfectly straight which gave some complications.

Here is some pictures of its construction :
Plywood sheets (1/2")


Insulation foam (1") and Reflectix insulator


The wooden base :


Beginning to put insulation foam (I varnished the interior wood with oil varnish before putting insulation foam):


Gluing the insulation foam on the wood. I put mecanical pressure to be sure the glue holds well :


The doors and cold strips to insulate better the sides of the doors...


The final product :


The ice compartment :


The two doors (one only to switch ice, and the other one to put my carboy inside) :


THe front view, with pencils and pens holding the doors tight (my gf will probably want her pens back soon...)


So, I'm very proud of having build this. I learned a LOT of things with it. First thing first : a project always take more time than predicted.

I'm running some test as of now about maintaining a good temperature. There's nothing in it, I just want to see how well he can holds the temperature. Right now, I managed to hold a 65 F for (it's not over yet) for at least 42 hours, which surprises me. There's still some ice left... so I'm very impressed and I think it can hold for at least 48 hours. With 4 liters of ice in Sprite bottles, which is about 1 gallon. My apartment is approximately at 75 F, so I have a small dT of 10F.

I was surprised that there's so much differences between a typical water bottle and a typical cola bottle. As an example, water bottles (Naya, Esker, Dasani and the likes) needed the fan to run all the time, but were holding the temperature OK for a long time. I couldn't cool, but I could maintain the temperature. However, Sprite and Coca-Cola gave their coolness faster so the fan could stop periodically from running.

Where does the air travel? I cant see any path for the cold air to go from the bottom units where the ice will be to the top where you fermenter will be.

Oh, I forgot to take some picture of this little detail . There's six holes (0.5" diameter) between the two ice compartments so the air circulate between the first and the second compartment, and there's three holes in the second compartment, on the the top, so the air can circulate from the ice compartments to the bucket.

You can see these three little dudes here :

Oh yeah, and to thank my friend for helping me out... I made him discover the truly greatest, one and only... Rochefort 10.

Erythro73 said:

Oh, I forgot to take some picture of this little detail . There's six holes (0.5" diameter) between the two ice compartments so the air circulate between the first and the second compartment, and there's three holes in the second compartment, on the the top, so the air can circulate from the ice compartments to the bucket.

You can see these three little dudes here :

Click to expand...

Still if the air is just being moved from the one chamber to the next where is the warmer air inside the larger chamber being drawn in. What I mean is you need to cause positive/negative pressure in the colder compartment to move the air around the whole unit by drawing in warm air from the carboy area with the fan otherwise the air will just circulate between the two little compartments.

That's great you will be able to have good temp control on your very first brew. I think two of the most important things for producing good beer are controlling your fermentation temperature control and patience.

springer said:

Still if the air is just being moved from the one chamber to the next where is the warmer air inside the larger chamber being drawn in. What I mean is you need to cause positive pressure in the colder compartment to move the air around the whole unit by drawing in warm air from the carboy area with the fan otherwise the air will just circulate between the two little compartments.

Click to expand...

There's no second hole on the back (above the fan) to push the warmer air behind the fan, if that's what you mean. In fact, it's as simple as it gets sincer the colder air won't push the hot air, but will only cool it. And by my tests I did, it works well. The cold air has to go cool the surrounding of the top portion of the chiller, as the fan push it through. Maybe not the most efficient, though. But, 46 hours after the beginning, it's still at 65F instead of 75F with 4 liters of ice. This way, the surrounding of the ice is always "cold" as to minimize ice's melting.

I was just thinking that it may be more efficient to move the air around the entire unit . Seems that if you drilled a hole in the back right corner and placed the fan under the three holes you would actually be moving the cold air around and the fan may run a lot less and the temps would be more stable from top to bottom of the unit.I have to run a fan in my kegerator as the air at the top is a good 7°-10°warmer than the bottom I have one in the fermenting fridge also .But hey if its working for ya now why mess with it

springer said:

I was just thinking that it may be more efficient to move the air around the entire unit . Seems that if you drilled a hole in the back right corner and placed the fan under the three holes you would actually be moving the cold air around and the fan may run a lot less and the temps would be more stable from top to bottom of the unit.I have to run a fan in my kegerator as the air at the top is a good 7°-10°warmer than the bottom I have one in the fermenting fridge also .But hey if its working for ya now why mess with it

Click to expand...

That's sure is a good idea, but as you said, its working now (plus moving the fan now would be a pain in the *** as the power lines are passing behind the pink foam.... a better way to do it would be to rotate the plywood sheet separating the ice compartments from the top part 180 degrees, but I get your idea). One of my engineer friend always says to me "If it ain't broke, don't fix it". (The problem with fixing it right now as your idea goes, it's that I don't have a drill with me... it's my friend who brought his... and well, our schedule doesn't fit very well together these times, so I prefer to give it a run with a true beer before doing anything).

If I have efficiency problems when I'll run it with a true fermenting wort, I'll be sure to check after your idea. Thank for the input!

(Now, I'm more excited about the idea of brewing my first beer than fixing minor problems who doesn't stop my fermentation chiller from going well)

I agree, I think the air needs to be cycled. That's kinda the whole point behind these chambers. Either you pull hot air from the top and push cold air in the bottom. Or push cold air to the top letting it sink to the bottom where it is drawn and cycled again.

OK, seems to me like both of you are right, finally.

Reading springer with his kegerator, I decided to test how the temperature was different, depending on the height. My thermistor was always on the "ground" (i.e. in the main compartment, where the bucket will be, but on the lowest possible height). I changed the height and put it 2 inches higher. The temperature rose from 65F to 72F.

I tried many things, but now this thing doesn't work. It can't hold the temperature to 18.5 Celsius even with all the ice...

Damn, and I thought I could finally brew my first brew tomorrow.

I think a few modifications and you will be fine. Bring the fn out a few inches and drill some holes to cycle the warm air through the fan. put ice in front of the fan and on the other side. Then move the holes on the other side to the back. This will draw the warm air down from the chamber over 4 or 6 bottles of ice, then back up into the chamber. Also consider using a piece of pvc pipe to push the outlet for cold air up to the top (3 or 4 inches from the top) of the chamber. The cold air will fall over your fermenter and help push the warm air down.

A few minor changes and you could be in business... Just my .02

I showed this thread to my friend, and we'll do the required modifications soon. Damn, I was sure it was working, but you and springer were right.

I need to have a better air circulation which can be achieve with your ideas.

This is nice! How many carboy can it contain? Where did you get the plans?

cell said:

This is nice! How many carboy can it contain? Where did you get the plans?

Click to expand...

It's designed for one carboy at a time (due to limited space in my apartment).

The original plans are there (but I modified it along the way) :

http://www.wortomatic.com/articles/38DD-Mother-of-a-Fermentation-Chiller

(But man... these doesn't seem to have a much better air circulation than mine)

Erythro73 said:

(But man... these doesn't seem to have a much better air circulation than mine)

Click to expand...

Same principals, but you can see the holes he has in the ice chambers - it forces the air in an "S" pattern over the ice, through the 3 chambers on the bottoms (this creates more contact with ice enabling a cooler temp) and then up into the ferm chamber.

You've got a really nice start going, and it looks great. Just needs some more holes and some beer to go in it. What's your first batch going to be?

I wish I needed to build one of these it is so sweet and a neat piece of equipment. I luckily have a basement at my parents house that stays about 55-60 degrees year around. Although I sometimes wonder if it is too cool. Maybe someday when I am out of my apt and have a house I will build one. I look forward to your final modifications.

BrewSpook said:

Same principals, but you can see the holes he has in the ice chambers - it forces the air in an "S" pattern over the ice, through the 3 chambers on the bottoms (this creates more contact with ice enabling a cooler temp) and then up into the ferm chamber.

You've got a really nice start going, and it looks great. Just needs some more holes and some beer to go in it. What's your first batch going to be?

Click to expand...

Yeah, there's some work to be done and we'll do it as soon as possible.

As a first beer, I was hesitating between a simple pale ale (let's start with more simple beers who doesn't take age to ferment... and something my family could drink) and a stout (these times, I only think about drinking a stout).

If I were you, I'd drill a hole in the back right corner of the chamber, and run a pvc pipe up the back of the chamber to pull air down from up high.

Then, I'd use some leftover insulation (or anything really) to seal the fan off across the chamber so that air HAS to pass through the fan when it's running. It will help to create circulation throughout the whole chamber, instead of just the one the fan in is.

So I have, according to your suggestions, redesigned my fermentation chiller.

Basically, I've drilled some new holes at the rear end of the chiller. One big enough to add a pipe and another which will basically serve the air circulation at the other side. I reverted the direction of the fan so the air is going into the pipe.

Here's some picture.

Here's the fan, reverted, with insulation foam so the air doesn't come back by there...


The holes serving air circulation between the two compartments of ice.


The holes for air circulation at the left rear end :


Here's the whole picture.


I didn't put it to extra-long test, but for short tests, it worked really well. For once, I can now have the desired temperature at the height I want .

I recently built a version of the 38DD mother of fermentation chiller but I've got a question about the warm air return, from fermentation chamber back to ice chamber. In the original Wort-o-matic plans and I think in Erythro73's version here, the warm air return is a hole drilled into the floor of the ferm chamber. I don't know much about thermodynamics but if it's true that 'heat rises' - should this warm air return be extended to protrude near the top of the chamber, as opposed to on the floor? (That way pulling warmer air at the top back into the ice chamber to be cooled, rather than pulling the cooler air at the bottom).

Any ideas?

http://www.wortomatic.com/articles/38DD-Mother-of-a-Fermentation-Chiller

simont said:

I recently built a version of the 38DD mother of fermentation chiller but I've got a question about the warm air return, from fermentation chamber back to ice chamber. In the original Wort-o-matic plans and I think in Erythro73's version here, the warm air return is a hole drilled into the floor of the ferm chamber. I don't know much about thermodynamics but if it's true that 'heat rises' - should this warm air return be extended to protrude near the top of the chamber, as opposed to on the floor? (That way pulling warmer air at the top back into the ice chamber to be cooled, rather than pulling the cooler air at the bottom).

Any ideas?

http://www.wortomatic.com/articles/38DD-Mother-of-a-Fermentation-Chiller

Click to expand...

I would have to agree with you, pull the warm air from the TOP and run that across the ice to cool and then re-enter at the bottom to furher push the warm air to the top and into the tube. upon reaching the target temp the fan would turn off untill the temp drops to the set point of the controller.

I don't know about the Erytho73 version, but the version on the Wort-O-Matic site should be set up so that the warm air is drawn from the upper corner of the cabinet, down the triangular shaped portion, through the 3 ice chambers under the floor and then returns to the chamber via the hole that is drilled in the chamber floor on the lower left corner (when looking at the plan view). The fan should be installed so that the direction of air flow accomplishes this.

gromitdj said:

I don't know about the Erytho73 version, but the version on the Wort-O-Matic site should be set up so that the warm air is drawn from the upper corner of the cabinet, down the triangular shaped portion, through the 3 ice chambers under the floor and then returns to the chamber via the hole that is drilled in the chamber floor on the lower left corner (when looking at the plan view). The fan should be installed so that the direction of air flow accomplishes this.

Click to expand...

Actually, I think that you want the air to go up the tube so that the cold air cools the warm air. Remember that cold air is heavier and by pushing it through those holes on the bottom you are not really getting good thermal cooling. By having the colder air push the warm air down the air will cool fast and also the fan will run less because there wont be any
warm air on top.

Sorry for ecto-mancing the thread!

if you add up all your holes sq inches . they need to equal the square inches of fan area. otherwise your starving it for air and it will try to suck outside air in through gaskets... not sure why would restrict it so much