Glycol/Iced Water (aquarium chiller and stc?)

[chrisolver]

Hey Everyone,

Need some advice with a bit of background.. Currently live in an apartment where space is very limited and the internal spare bathroom has become the "brewery room". Last year I was find temps in that room during the summer was leaving my beer fermenting at 30c+. Stupidly hot. I also have a love for lagers for every day drinking that I wanted to brew at low temps.

So last year I nabbed a grays auction for a chest freezer that is moved around on a bunnings dolly. Its done me alright for a year or so but lifting a 30l fermenter in and out is starting to drive me nuts and well it takes up the whole bathroom. So it has to be moved in and out whenever I brew another beer. So I was really excited to see that Grainfather are releasing a SS Fermenter and Glycol. I was then really disappointed to find out the RRP price for the fermenter with controller and glycol chiller comes in around $2,500. That's more expensive that my whole setup.

So I currently use a SS Brewtech Brew Bucket and was thinking of buying the addon FTSs ($400) for it. The next question is what to use to provide chilled water.. My current thinking is to use an esky as a reservoir and an aquarium chiller to provide constant chilled water (grab one from ebay).. I know a lot of people say throw ice bottles in the esky every day but want something more lazy and automated

I know most chillers can be set to go down to 4c in temp, so looking at a few diagrams it looks easily enough to use an STC controller to make these things go colder than the standard controller allows. Google has provided some answers but no one has specifically said if they have modded an aquarium chiller to go lower.

Thoughts or recommendations about using an aquarium chiller? Has anyone done it before?,

ta

 

[good4whatAlesU]

Hi Chris, good idea and will be interested to see how you go. I looked into aquarium chillers a while back but soon discovered the good ones would be dearer than buying a good used second hand fridge anyway.

I notice online they have some thermoelectric coolers (soft and solid cooler bags) for less than $150. The hard body ones claim to get up to 20 celcius below ambient which might be worth a look if you can find one that would fit your fermenter. Match it to a thermostat and away you go.

http://m.ebay.com.au/itm/Thermoelectric-Cooler-Warmer-33L-Family-Size-DC-12V-Only-Free-Delivery-Melb-/222492154122?nav=SEARCH

http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=262922803037&category=181382&pm=1&ds=0&t=1494794006402

 

[paulyman]

Hi Chris,

I have a brew bucket with FtSS which runs from a keg of water in my kegerator. The kegerator is in the back room set at 2C. Our house is quite old and uninsulated, so in summer it was hitting 34C back there and at the moment is ranging from 5 to 15 each day, big swings. During summer the FTSS could only hold temp at 18-20 and even that was a struggle on both it and the kegerator. Even now it won't hold lager temps but can hold low 12-16. It's doing the job but I want a bit more response and ability to lager.

I'm sure the aquarium pump chilling just the water and not the fridge will be a better option.

I have been trying to source the ssbrewtech glycol unit but it seems like it just isn't coming to Aus, at least for a realistic price, which sucks. I think they are brilliant in that you can independently control fermentation on up to 4 fermenters, in the same space as a single chest freezer. But the price I've seen to import is not much below the grainfather package including the fermenter, so I might have to look there.

 

[klangers]

I'm not sure the aquarium cooler will go cold enough.

More specifically, any refrigeration system loses refrigeration capacity as it approaches it's lowest possible evaporation temperature. So, I would be extraordinarily surprised if the aquarium cooler would have remotely near the necessary capacity at -5 to 0 degrees. Remember you need a rather steep heat gradient - you're evaporating the refrigerant and transferring heat out of the glycol, which in turn transfers heat out of the fermenter. So if you're looking to cold crash you'd really need a -10 evaporation temp.

For example, a 400 watt aquarium cooler might indeed cool by 400 watts at 20 degrees, however, at 4 degrees it will be far, far lower. Maybe as low as 150 watts. If you attempted to override the control system to push it as low as it can go, it will go cooler until the refrigeration capacity (which decreases the lower we get) is matched by the heat input from the recirculation pump work. This would then have zero refrigeration capacity; any additional heat you pick up will raise the glycol temperature.

"Modding" the control system won't change this fact, unfortunately. It's a limit of the compressor and refrigerant type and charge.

Typically, glycol is reticulated at -10 to -5 degrees. This allows a minimum flow of glycol (higher flow = higher heat load from pump work) to achieve a decent heat transfer rate. Aquarium coolers might work OK for fermentation temperatures in ales, but I'd be very hesitant to go to the above effort unless you can find out a capacity chart of the cooler.

 

[chrisolver]

During summer the FTSS could only hold temp at 18-20 and even that was a struggle on both it and the kegerator.

So nearly freezing water struggled to get it lower direct from the kegerator? I have heard that some people have recommended getting the extension arms for the insides to get the chiller further in. Is the fermenter insulated? Wow, I would of thought the ice cold water would of dropped it further.

"Modding" the control system won't change this fact, unfortunately. It's a limit of the compressor and refrigerant type and charge.

Much appreciated for the information. I made a very simple assumption that it was simply a limitation on these devices so it didn't kill the fish.

I did find that this model via a google search will drop down to 4c - http://www.theaquariumsolution.com/dc-300-refrigerated-cooler

 

[klangers]

Much appreciated for the information. I made a very simple assumption that it was simply a limitation on these devices so it didn't kill the fish.

I did find that this model via a google search will drop down to 4c - http://www.theaquariumsolution.com/dc-300-refrigerated-cooler

If you check out the graph on the site, you can see what I'm talking about. The graph is of "aquarium temperature over time", so the slope is proportional to refrigeration capacity. It's steepest in the high 20s, and gets flatter as the temperature drops. Extrapolate the (negative logarithmic) graph and you can see that the lowest feasible temperature is around 12 degrees.

 

[paulyman]

So nearly freezing water struggled to get it lower direct from the kegerator? I have heard that some people have recommended getting the extension arms for the insides to get the chiller further in. Is the fermenter insulated? Wow, I would of thought the ice cold water would of dropped it further.

I think it's the fact the cooling water is being cooled indirectly by the kegerator. If the cooling coils were in direct contact with the cooling water it would be much more efficient.

 

[malt junkie]

If you check out the graph on the site, you can see what I'm talking about. The graph is of "aquarium temperature over time", so the slope is proportional to refrigeration capacity. It's steepest in the high 20s, and gets flatter as the temperature drops. Extrapolate the (negative logarithmic) graph and you can see that the lowest feasible temperature is around 12 degrees.

Then again it's a 300w cooling system I'm sure like most things bigger is better; you can't whip cream with a tooth pick!

 

[klangers]

That's my whole point though, bigger doesn't mean better.

You can get the biggest fridge system ever built, but if its suction and evaporation pressures aren't set up around your duty point then it can never get there. A freezer isn't just a more powerful fridge, for example. A freezer has a different refrigerant charge and different pressure differentials across the evaporator.