Swamp cooler and Temperature control

[kaiserben]

I'm keen to make a few lager styles in my apartment (will start with a schwarzbier) and the only viable method of hitting the right temperatures is via a "swamp cooler".

(FYI As background info I've just done an ale under normal conditions and the ferment temperature is a constant 19-20 degrees C in the cupboard I'll be using).

My initial thought is to sit my 30L FV inside a 60L plastic garbage bin with lid, which will leave just enough room to put a bit of water and ice to chill what's inside the FV.

I could also no-chill AND primary ferment in 2 x 10L Jerry cans if anyone reckons they might give me another, better option to hit and maintain the right temperature.

So my concerns are:

1. The stick-on thermometer won't survive being submerged water (I've trawled forums and found that out in advance).
2. So how can I accurately know what temperature I'm fermenting at? (even if the stick on thermometer survived water-logging it surely wouldn't be giving an accurate reading of what's going on inside the FV while it is submerged in water likely to be colder than what's in the FV).
3. Can I maintain a reasonably constant temp, at the correct temp for lager yeast, by adding a certain amount of ice, say, once every 24 hours? Or 12 hours? Or ... ???

And my only idea is:

Could I do a "dry" run and keep testing the temperatures of water inside the FV and surrounding the FV too see the difference between temps inside and outside the FV, so that when it comes to doing it with an actual ferment going on I'll be able to make an educated guess on ferment temp by using a glass thermometer in the water surrounding the FV? (is this making sense?)

I know people have done this successfully, but I couldn't find a mention of how people knew they had the right temperature.

Ideally I'm hoping someone who has done this will just tell me that the liquid outside the FV is aprrox. X degrees less than what's inside the FV and it's as easy as that.

Any reassurances and/or ideas appreciated.

 

[Coxy]

BYO has a useful article on this, in case you haven't read it yet:

https://byo.com/bottling/item/1869-controlling-fermentation-temperature-techniques

They suggest simply keeping the thermometer above the water line if you are doing an ice bath, as you are planning to do. The "wet T-shirt" technique looks pretty easy in case you wanted to do that instead.

Having someone just tell you the liquid outside FV is approx X degrees less than what's inside is not going to happen - it will depend on how often you are adding ice and at what temperature, what your volumes are, ambient temp, etcetera. If you kept the liquid outside at exactly the temperature you were aiming at for the entire time, then clearly the temperature inside will be the same. However, this is not possible to do with an ice bath. When you add the ice, outside temp drop down below your target ferment temp., then will slowly raise up to above your target ferment temp. The temperature inside the FV will be far less volatile, explained best through an example.

For example, if inside temp = 14C and outside temp = 14C, you add a bunch of ice so that the outside liquid temp is 1C but inside temp is still 14C. Inside temp will go down as outside temp rises (thermodynamics 101). There will be a time where the outside temp and inside temp reach an equilibrium, maybe somewhere around 8C (exactly what temp will depend on relative volumes of the two liquids and also less so on ambient temperature heating the liquid). The outside liquid temp will continue to rise towards room temperature, but from this point the two liquids should rise in temperature almost together, remaining very close to equilibrium.

So generally, each morning before you add ice, the inside temp is likely to be very close to the outside temp. Immediately after adding the ice, they will be nowhere near close to each other, then will slowly reach an equilibrium point again and then slowly come towards room temperature. There is no rule you can use to compare inside temp to outside temp such as 'X degrees difference'.

Good luck, and if you can find a spare fridge on the side of the road during the next council pick up, grab it. My first fermentation chamber was a very rusty old freezer that I snagged off the side of the road and hooked up a $20 aquarium temp controller from ebay to it. It's much easier than freezing ice every day.

 

[stewy]

I've found that with my swamp cooler setup I can keep the temp at a very steady 6c below ambient - this is the setup

23L in fermenter
Fermenter placed in an esky (the soft fabric type on wheels with a handle)
Water filled to cover approx 2/3rds of wort volume
Wet towel placed all over fermenter with both ends submerged
2 600ml Mount Franklin water bottles frozen placed in the water rotated twice daily (I.e. I place 2 frozen bottles in at 6am, change them for 2 fresh frozen bottles at 6pm)

It works exceptionally well. Obviously if you add more/bigger frozen bottles you could vary how much below ambient you get. It's also important to note that my garage is under the building tucked away a bit, a concrete dbl garage & the ambient temperature doesn't change at all during day/night, so it's much more predictable than an area that might be 15c overnight & 22c during the day.

Hope this helps

 

[Coxy]

Stewy, I think the main thing the OP is trying to work out is exactly what the fermentation temperature is inside the fermentation vessel. e.g. with your set up, how do you know it's a steady 6C below ambient if a stick thermometer doesn't work while submerged? I'm guessing you just have the stick above the waterline?

 

[calobes]

I'm keen to make a few lager styles in my apartment (will start with a schwarzbier) and the only viable method of hitting the right temperatures is via a "swamp cooler".

(FYI As background info I've just done an ale under normal conditions and the ferment temperature is a constant 19-20 degrees C in the cupboard I'll be using).

My initial thought is to sit my 30L FV inside a 60L plastic garbage bin with lid, which will leave just enough room to put a bit of water and ice to chill what's inside the FV.
I could also no-chill AND primary ferment in 2 x 10L Jerry cans if anyone reckons they might give me another, better option to hit and maintain the right temperature.

So my concerns are:

1. The stick-on thermometer won't survive being submerged water (I've trawled forums and found that out in advance).
2. So how can I accurately know what temperature I'm fermenting at? (even if the stick on thermometer survived water-logging it surely wouldn't be giving an accurate reading of what's going on inside the FV while it is submerged in water likely to be colder than what's in the FV).
3. Can I maintain a reasonably constant temp, at the correct temp for lager yeast, by adding a certain amount of ice, say, once every 24 hours? Or 12 hours? Or ... ???

And my only idea is:

Could I do a "dry" run and keep testing the temperatures of water inside the FV and surrounding the FV too see the difference between temps inside and outside the FV, so that when it comes to doing it with an actual ferment going on I'll be able to make an educated guess on ferment temp by using a glass thermometer in the water surrounding the FV? (is this making sense?)

I know people have done this successfully, but I couldn't find a mention of how people knew they had the right temperature.

Ideally I'm hoping someone who has done this will just tell me that the liquid outside the FV is aprrox. X degrees less than what's inside the FV and it's as easy as that.

Any reassurances and/or ideas appreciated.

Buy a thermometer from a kitchen shop, like a mash thermometer submerge it in the water.
thats what I do, I use this method even during winter with an aquarium heater.

 

[stewy]

I have the stick above the swamp cooler water line, but in line with top 1/3rd of wort. The question is how long until the wort is the same temp as the swamp cooler water, as laws of thermo tells us it will be eventually. You would imagine it would be plausible to get them at equilibrium during lag phase after pitching yeast, but depends what temp the wort starts at I guess. I must say, I would be more concerned fermenting a lager than an ale

 

[Coxy]

I have the stick above the swamp cooler water line, but in line with top 1/3rd of wort.

I'd say that's the best solution for sure.

 

[Black n Tan]

A swamp cooler is an American term for an evaporative cooler. The methods described above are not really relying on evaporation to cool, and hence are not 'swamp coolers'. Evaporative coolers work best in low humidity environments. If you want to use evaporation to cool rather than ice, then wrap the fermenter in a towel and place in a container with say 10-20cm of water such that the towel acts as a wick and draws the water up. Use a fan to blow on the towel to cause evaporation which will result in cooling.

 

[Funk then Funk1]

Buy a thermometer from a kitchen shop, like a mash thermometer submerge it in the water.
thats what I do, I use this method even during winter with an aquarium heater.

Same here, frozen bottles in the water swapped twice a day and a wet towel over the top with the thermometer in the water the whole time. the main problem with this is as the ambient temp warms up you do get a little bit of variation in you temps over the day.
Also choose the yeast to suit your temp, if you can't get it low enough 10-14 degrees for most lager yeasts, then you can try the swiss lager yeast, with it you can still brew a good lager at 18-19 degrees.

 

[kaiserben]

I've seen mentioned that even the 'wet t-shirt' method ruins a stick-on thermometer.

I'm hoping to avoid running a fan for days on end - or another fridge for that matter (would running a modified bar fridge at only lager temps be fairly cheap to run? I'd need to convince SWMBO that getting another fridge/freezer isn't going to change our electricity bill all that dramatically).

Perhaps this Swiss Lager yeast will have to do until I can test out what temps I can maintain using my water/ice in garbage bin method.

 

[kaiserben]

Looks like my LHBS doesn't stock S-189 so, from what I can tell, Mangrove Jack's 'Workhorse' M10 might do a similar job.

 

[superstock]

Get an old fridge or chest freezer (preferred) = insulated fermentation chamber, even if not running and use frozen water bottles in that.

 

[Funk then Funk1]

Looks like my LHBS doesn't stock S-189 so, from what I can tell, Mangrove Jack's 'Workhorse' M10 might do a similar job.

Craftbrewer has it, not too sure how much postage would be to Sydney though.

 

[kaiserben]

I ended up getting WL810 San Francisco Lager Yeast.

Pitched it at 9pm last night at 22 degrees C into a 10L cube/fermenter as per instructions on the vial.

This morning at 9am (so 12 hours after pitching) I put the FV into a plastic garbage bin with water (and some no-rinse san) filled up to cover about halfway up the FV. I then added an ice cube tray amount of ice and also a 1L glass jar of ice. Hopefully this won't shock the yeast too much??

I'll put some new frozen bottles in tonight and keep replacing every 12 hours for about 5 days I suppose (or till I get sick of doing it). I'll keep track of what temps I'm getting. There could be some wild fluctuations, so I dunno how well this is all going to work.

After 5-ish days I'll allow the temp to rise to 20-ish for 2 days (as a diacetyl rest), then think about how I'll bring the temp right down - maybe bottle at this point and then leave bottles in the house fridge for a day (to lower the temp a fair bit, but not straight down to 0C), then put a few into the house freezer for a proper lagering?? (the beer won't freeze unless it reaches -2C from what I've read)

Any tips/suggestions more than welcome here. (I think this process has just proven to me that I'm eventually going to have to get a bar fridge and a temp controller)

 

[kaiserben]

So when I got home from work today the ice had obviously melted. The temp on the FV said 18C (measured with a stick-on thermometer)

I added a fresh ice bottle and a couple of hours later temp seemed to be sitting at about 11C (although the bottom limit of a stick-on thermometer is 10C, so I guess maybe it's below, because both the 10C and 12C boxes have blue colour in them - see attached photo) . I replaced the ice bottle at this stage and repeated every couple of hours- and the temp seems to be holding steady at that 10-12C area of the thermometer.

Overnight the temp will probably end up at about 18C again, as I'll be asleep and not changing the ice bottles over.

In the morning I'll put a fresh ice bottle in and head for work. Then repeat this pattern each day (with ferment temp fluctuating between 10 - 18C).

On the weekend I'll test gravity and see how it's all progressing.

 

[maxim0200]

In summer I sccuessfully use a STC with a damp/wet towle and a fan connected to the STC pointing at the fermenter.
I have kept it at 18DegC for pale ales but I never tried to go cooler.

You could easily just use the STC as a temp gauge with nothing plugged/wired in.
I have used both a thermowell and I have stuck it straight into the beer to no I'll effect.

 

[pat86]

Mate I'm not sure if the fluctuations between 10-18C will be good for your beer. Much better to maintain a steady 18 for ales or a steady 16C etc than have it swing so much. Lagers I wouldn't do without temp control but you could easily do good clean ales at their lowest term temps - eg. 14-16C depending on the yeast strain

 

[kaiserben]

The only constant temp I can rely on is about 20-22 degrees C.

I was hoping I wouldn't get such wild fluctuations keeping it cool this way.

So what should I do with this batch? I've likely put the yeast to sleep (according to the online research I've done). Should I keep doing what I'm doing and maybe roll the FV (but not aerate it) each day to get the yeast in suspension a bit more? Shall I give up on cooling and let the temp head towards 20, maybe roll the yeast off the bottom a bit and leave it to hopefully finish?


EDIT:
I just checked and I detect tell-tale signs of fermentation actually happening. A bit of a sulfur smell. What looks like a very thin layer of krausen on the top. A bit of crud a centimeter or so above that. It's now 48 hours since I pitched the yeast.

 

[oznewbie]

How warm are you guys in sydney at the minute?
I was getting 22c in brisbane, in my bar room. It is well insulated, I was hoping to get a decent steady temp of 16-18 with the fermentor in an esky full of water and a towel up and over it.

 

[kaiserben]

Last 2 days have been warm - over 30 C outside.

I think my (stick on) thermometer may have carked it due to condensation, because it's been reading constantly ~16-18 C using the same frozen bottles in water bath method that was getting me 10-18 C for 2 days prior.