Small Batch Mash Temp Control

[Cainmos]

TLDR: For small 1-2 gallon BIAB batches does anyone know of a food safe sous vide style temperature controller?

I personally usually brew small one gallon BIAB batches on the stove because I like to experiment with recipes and the equipment required isn't anything beyond what I already have in the kitchen. Otherwise I do 5 gallon BIAB on a burner.

I have have found that I am unhappy with the accuracy of temp control during mashing on the stove. Not all stoves are created equal so sometimes this isn't a problem. However, with such a small thermal mass on the 1gal batches and a crappy stove I find it difficult to really dial in within a few °F for the entire mash while acting as a human PID. While I know for what I'm doing this doesn't make an insane amount of difference in terms of homebrew level quality, I want to be able to transfer good repeatability to larger batches and mash temp is a huge factor.

I recently purchased an Anova sous vide cooker and feel like using this will eliminate the headache with small batch temp control. In reading threads dug up from the past it seems to work rather well but there are concerns of food safety and wort burning to the element. Personally I am not super concerned with this but was wondering if anyone knows of an existing sous vide style cooker that is more geared toward brewing. So far I can't find anything other than RIMS type systems that aren't really conducive to the small batch size and minimal equipment​.

 

[wilserbrewer]

Have you tried placing your mash kettle in a warm oven to keep temps stable. Very positive reports by many....

Don't strive for perfection imo, a narrow range is all you need.

 

[jurgenph]

not really a direct answer to your question, but i mash my small batches in a 2 gallon cooler, and it holds temperature very well.


J.

 

[Weezy]

Use the sous vide in larger water bath (maybe a rectangular cooler, etc), with your mash pot inside the bath.

When I did stove top, i just baby sat it with a thermometer jammed in the mash. Getting cool? Turn on burner to low and stir like mad for a couple minutes. If you biab with a very fine crush, id get 75-78% efficiency with a 20 minutes mash.

 

[Cainmos]

Have you tried placing your mash kettle in a warm oven to keep temps stable. Very positive reports by many....

Don't strive for perfection imo, a narrow range is all you need.

I have thought about that. Not sure why I haven't actually tried it though. Ill have to check how low "warm" is for temp.

not really a direct answer to your question, but i mash my small batches in a 2 gallon cooler, and it holds temperature very well.


J.

I haven't used the cooler method but this may be something to try as well. Do you mash directly in the cooler and then transfer to a pot for boil?


Thank you both for some different input. I know I don't need perfection but I would like better control at this point. I think the original idea was that I liked the idea of being able to visually see the temp stay constant.

 

[jurgenph]

I haven't used the cooler method but this may be something to try as well. Do you mash directly in the cooler and then transfer to a pot for boil?

this is my workflow

- heat mash water to around 170F or so
- put bag in empty cooler
- pour the heated water in cooler.
- close the cooler lid, and let it warm up for about 10 minutes or so.
- when you reach your desired strike water temperature (~160F for me), pour your milled malts into the bag in the cooler, and mix/stir, check temperature to make sure the mash temp is not too low/high. if it's too high, stir a little longer too low, add a little hot water.
- cover, and wait until your mash time is over. or stir once in a while if that's your thing, keeping in mind openingthe cooler and stirring will result in some heat loss.
- drain cooler into boil kettle

- i will now add more hot water to the cooler to do a batch sparge, this is optional, but you'll get better efficiency.
- after 10 minutes, drain again into boil kettle

- if you don't sparge, add more water to the boil kettle to get to your full boil volume.

- light the fire under the boil kettle, and put the bag of wet malts into a colander, dripping into the cooler.
- when the kettle reaches aboil, pour the rest of the cooler drippings into the kettle.
- when it reaches a boil again, start your timer


J.

 

[meatcleaver]

I biab (cheap electric stove) & have been having the same issues.
I'm leaning towards mashing in a cooler since I already have one but have heard of folks using their Crock-Pot/slow cooker with a temperature controller with good results.

 

[billsea]

I did many 2.5 gal batches on the stove top. Wrapped the pot with reflectix, checked the temp every 20 min. and added boiling water to raise. But, I am now using the oven. I did several dummy batches with water to test how to keep the temp stable. I put a digital reading corded probe thermometer into the oven to get a more accurate reading of the oven temp.

In my oven (yours may differ) I preheat to 170F (my lowest setting) while I am heating the mash water. I mash in on the stove top at the desired temp then put the pot (covered) in the oven. Then I turn the oven to 350F and wait till the oven temp reaches about 190F, takes about 30 seconds. Then turn off the oven. I know, this sounds way too hot, but testing will prove what your oven will do. After 10 minutes I check the temp of the mash (usually spot on), and turn on the oven again until it reaches about 190 on the digital thermometer. Check again after another 30 minutes and reheat. Testing will show what your process should be for a 1gal batch. You can run tests and test the temp of the mash at different times until you get your confidence in the process. Then it will be easy. I am achieving much better temp control of the mash than I did on the stove top.

Put a cookie sheet on the bottom rack and the pot on the second rack so that heat is more evenly distributed.

 

[Cainmos]

Billsea, now that is an interesting method of blast heating the mash haha. It actually kind of makes sense that a higher temp like that is needed (admittedly I wouldn't have thought as high as 190).

I think we have some great responses in here to different methods of overcoming small batch mash control.

I am thinking my next batch I will try the oven and maybe also the cooler with the sous vide cooker in a water bath. See which hold better for my setup.

Cheers for all the responses!

 

[NSMikeD]

I used the oven (gas) as well. It's lowest temp setting in 170° and it's ridiculously inaccurate - up to 25° off at times, more in spots when pre-heating. It also loses heat quickly once turned off.

This week I decided to employ my Maverick ET -733 dual pro thermometer using one probe in the mash and the other clipped to the grate. I was seeking a 90 minute mash @ 150° for a 2.5 gallon Krolsch. For some reason the mash began at 153°, no big deal. The remote thermometer enabled me to monitor the mash and oven while I relaxed in the TV room. I preheated the oven to 170°and then turned it off when the mash began. The oven temp dropped about 25° with that initial opening the oven door.

It took about 30 minutes for the mash to drop the desired 3°. At that point i chose to reheat the oven to 170° three times. The final mash temp was 149° so that was a 1° drop over 60 minutes.

Knowing the ambient and mash temp in real time was very useful and resulted in my tightest mash to date. No need to open the oven door, no surprise mash temp drops and no over shooting from adding additional heat.

+1 on putting a tray or stone on the bottom rack. The temp on the bottom grate was 300+ when the oven was firing up even though the oven was set for 170°

Using the dual probe thermometer is a game changer for me and I will be using it going forward.

 

[brew_darrymore]

Your process is exactly the same as my process - bag in a cooler. I use a round Igloo cooler and temperature drops only one degree F in 60 minutes. I stir once at 15' when I draw a small wort sample to measure mash pH.

this is my workflow

- heat mash water to around 170F or so
- put bag in empty cooler
- pour the heated water in cooler.
- close the cooler lid, and let it warm up for about 10 minutes or so.
- when you reach your desired strike water temperature (~160F for me), pour your milled malts into the bag in the cooler, and mix/stir, check temperature to make sure the mash temp is not too low/high. if it's too high, stir a little longer too low, add a little hot water.
- cover, and wait until your mash time is over. or stir once in a while if that's your thing, keeping in mind openingthe cooler and stirring will result in some heat loss.
- drain cooler into boil kettle

- i will now add more hot water to the cooler to do a batch sparge, this is optional, but you'll get better efficiency.
- after 10 minutes, drain again into boil kettle

- if you don't sparge, add more water to the boil kettle to get to your full boil volume.

- light the fire under the boil kettle, and put the bag of wet malts into a colander, dripping into the cooler.
- when the kettle reaches aboil, pour the rest of the cooler drippings into the kettle.
- when it reaches a boil again, start your timer


J.

 

[billsea]

I should add that the reason I check the temp twice during the mash is because I stir the mash at that time. I think that stirring the mash increases my efficiency. When I open the oven and stir, this reduces the oven temp, so I turn the oven back on to account for that. If you don't want to stir you could probably go for the full hour without doing anything.

 

[RM-MN]

I have thought about that. Not sure why I haven't actually tried it though. Ill have to check how low "warm" is for temp.





I haven't used the cooler method but this may be something to try as well. Do you mash directly in the cooler and then transfer to a pot for boil?


Thank you both for some different input. I know I don't need perfection but I would like better control at this point. I think the original idea was that I liked the idea of being able to visually see the temp stay constant.

The answer to that is, "it doesn't matter". Suppose your oven has a lowest setting of 200F. Your mash will be about 155+/- The oven will cool some during the mash, the temperature difference is ~50 at the start which is a bit different than the (155-72) ~80 of room temp which doesn't change much during the mash.

Now suppose you mill your grain fine. Conversion will be over in less than 20 minutes (depends on how fine is "fine") and your mash temp won't have changed more than a degree.

If you merely put the mash tun in the unheated oven you would get similar results because the mash will heat up that confined space quite a bit in a short time anyway. It can't heat up an entire room.

 

[ericbw]

If no one else said this: remember that even though the air in the oven changes temp fast, the wort is liquid so the change is slower. Getting to the right mash temp at first is your best bet.

And others have said: bag in a cooler. Try a 2 gallon for small batches. I use a 5 gallon, and I often don't even check the temp during the mash.

 

[Sadu]

I ended up with a recirculating mash system for my 1G batches (somewhat overkill) and love it. Prior to that I would put the pot in the oven and temperatures were pretty much stable so long as you dough-in at the correct temperature.

I also tried mashing in a cooler (total disaster) and temperature controlled crock-pot (good, but not quite big enough).

 

[Oginme]

Billsea, now that is an interesting method of blast heating the mash haha. It actually kind of makes sense that a higher temp like that is needed (admittedly I wouldn't have thought as high as 190).

I think we have some great responses in here to different methods of overcoming small batch mash control.

I am thinking my next batch I will try the oven and maybe also the cooler with the sous vide cooker in a water bath. See which hold better for my setup.

Cheers for all the responses!

I use my oven for 10 liter batches most of the time. The minimum temperature it will heat to is 170F and I turn it on while my strike water is heating up. After mashing in , I cover the pot and place it into the oven. I close the door and give the oven 2 to 3 minutes to reheat back to temperature. I then turn the oven off and let it rest for the remainder of the mash time. The object is to get the inside of the oven (walls, rack, etc.) heated up to temperature to act as a buffer to heat loss. As others have pointed out, the air temperature will change fast, but the inside of the oven and the mash pot will change much slower without a large temperature differential and once closed, the air inside the oven will help buffer the change.

Over an hours mash time, my temperature drop at the high end (158F) is around 3F and at the low end (150F) it maintains a stable temperature.

 

[pocketmon]

I ended up with a recirculating mash system for my 1G batches (somewhat overkill) and love it. Prior to that I would put the pot in the oven and temperatures were pretty much stable so long as you dough-in at the correct temperature.

I also tried mashing in a cooler (total disaster) and temperature controlled crock-pot (good, but not quite big enough).

How do you recirculate the wort?

I am thinking about use my spare components to make a complete spare controller as backup, and a 1Gal experimental system seems to be a good idea to make the backup controller useful. Kettles that have valves installed are bigger than I want. I am not sure if I can install a ball valve to a small kettle.

 

[Revvy]

Oh, here we go..... First skim through our various Ghetto Sous-vide controller setups in this thread, and imagine there being grain/water in them....

The order an STC- 1000 aquarium temp controller and build yourself one using my diagram...

My simplified explanation can be found here....

My parts list for the controller box is here.....

Now you need to decide what type of "vessel" you want to use.... One trick is to walk through the aisle of a salvation army's kitchenware aisle and look at things like big crock pots, Electric turkey roasters, or, and this is my suggestion The largest coffee urn you can find. for small batch brewing a 2-3 gallon one would be perfect... Just makes sure that whatever you decide on is ANALOG, not digital Since the stc-100 controller/wiring setup basically relies on turning the sockets the thing is plugged into "on/off" we found that digital appliances won't turn back on or lose their settings when this happens.

You can usually find these and most second hand stores for dirt cheap, sometimes massive 5-10 gallon ones can be found for 20-30 bucks ( But they go by fast, I know from experience as a minister starting churches, anyone starting a church on a budgets grabs these the minute they see them.) But the 2-3 gallon ones can be found for 5-10 bucks.

With a 2 gallon coffee urn using a NORMAL water to grain ratio of 1.25 quarts/ pound of grain, you can mash 5 pounds of grain , you can squeeze more in with a thicker mash ratio. With a 3 gallon urn at 1.25 you can get 7# in it, and at 1 quart per pound you can get 9# in it... I used the calculator "Can I Mash it" on the greenbay rackers calculator site.

Then you build some sort of thremowell to protect the temp probe from your stc 1,000 and suspend it into the pot... this is a quick snap in my messy kitchen of my sous-vide setup.... The easiest thermowell to make is to take the metal "core" of the coffee urn that usually moves the water up into the basket where the coffee sits in theses things, close the bottom end (crimping and sealing with some foodgrade silicone, or just crimping and rolling it) and find some way to put it into the urn... I used a simple piece of wood with a hole in mine.... (ignore the second hole and blue hose, that's just an aquarium pump airstone that I use for sous-vide cooking to keep moving the water around to keep the temp even.)

So basically you have the perfect 1-2 gallon sous-vide controlled mash tun.... all you need now is to line it to keep the grain from going out the spigot... you can do that like I showed in a thread on how for 1-2 gallon batches you can use an unconverted 2 gallon cooler as a mash tun, by using a mesh bag (just like BIAB-ers do.)

Just hang a mesh bag in it and secure it around the outside of the urn... Kinda like this bad picutre..

And basically bob's your uncle... the urn already has a spigot.... if you were creative you could hook a hose and pump to it and recirculate you mash even.. but I don't think you need to get that fancy smancy, just get a half gallon plastic pitcher and "vourloff" it by hand, -drain, pour, drain pour.... easy peasy.

You can do this for probably 50 bucks if you hunt around, and don't even buy fancy hardware stores stuff for the controller....

And these things are reliable- like i said, this is no different than cooking sous-vide this way, I've run mine for 3-4 days slow cooking pork belly this way... so you could setup easily for an over night mash if you wanted.



And yes there are thread all around the web, and on here, of folks making all electric coffee machine breweries... Big in Egland- the hard part is just finding used large coffee urns, cheaply.... Buying from a closed resaurant is a good bet.

 

[Cainmos]

Well damn. Thank you for that post Revvy!

 

[Weezy]

Always lived the simplicity of this build. I ran the same sous vide controller and a thermal wire for a long time, until it ultimately died.

https://www.homebrewtalk.com/showpost.php?p=5041282&postcount=11

 

[Vedexent]

What I tried is an Inkbird controller, and a simple one burner "hotplate" ( not an induction burner - I haven't seen a reasonably priced one that can't be controlled externally yet ) for my 2.5 gallon, full volume mash/boil, BIAB process, with a inverted colander as a false bottom to keep the direct heat from scorching the mash.

I think that this setup worked very well to hold the temperature, but it was very slow raising the temperature above ~140F - although I have not insulated the kettle at all (yet).

I was still able to do a multi-rest mash process with it, but I ended up lifting it back on the stove to boost the temperature, then return it to the hotplate to "dial in" the last degree or two, and to hold it at that temperature rest.

There were also some problems with keeping the probe placed correctly in the kettle ( I just had it "trapped" between the side of the kettle and the mesh bag ) - but I may devise some sort of holder to clip on the side of the kettle to at least keep it in a consistent position in the wort.

 

[SanPancho]

I recently purchased an Anova sous vide cooker and feel like using this will eliminate the headache with small batch temp control​.

At batch sizes under 2-3 gals it cant be beat. Above that, its underpowered. If you dont like the plastic in your mash just take the bottom cap off.

I dont do step mashing or anything fancy, but it still provides perfect temp control. Just keep your bag clear of the impeller and all good.

Wort scorching is not an issue in the mash. If you use it to maintain high whirlpool temps (185) you will get a bit of wort/hop burn onto element, but its pretty minor. But at typical mash temps, its not an issue ive ever had.

 

[wilserbrewer]

This thread is a prime example of how some homebrewers are compelled to complicate the process. What is so important about holding a precise mash temp to a degree? The enzymes are pretty smart and seem to easily figure the job out in my brewery? Let your strike temp dictate, and let the mash either fall or rise and mash within a temperature range.

Say one mashes in at 148-150, places the kettle in a preheated oven at 170 and just leaves the oven on and the mash warms 10 degrees over an hour.

I don't really see a problem with such a mash schedule? Most of the conversion is over in 10-20 minutes and the mash will only warm several degrees in that time. Lower mash temps start at say148, higher mash temps start at 153 -154 whatever...the mash is not going to go beyond 160 that quickly so plenty of time for conversion.

Adjust strike temp on future batches to tailor attenuation as needed, and keep your mash temp fluctuation fairly constant batch to batch.

KISS folks, just my $0.02

 

[Weezy]

This thread is a prime example of how some homebrewers are compelled to complicate the process. What is so important about holding a precise mash temp to a degree? The enzymes are pretty smart and seem to easily figure the job out in my brewery? Let your strike temp dictate, and let the mash either fall or rise and mash within a temperature range.

Say one mashes in at 148-150, places the kettle in a preheated oven at 170 and just leaves the oven on and the mash warms 10 degrees over an hour.

I don't really see a problem with such a mash schedule?

Adjust strike temp on future batches to tailor attenuation as needed, and keep your mash temp fluctuation fairly constant batch to batch.

Temp drift is a serious problem for us small batch brewers.

It makes hitting precise strike temps (and hoping mash temp is right) moot. 3-4 degrees is noticeable, especially if you're using low attenuating yeast.
And you can step mash.

 

[wilserbrewer]

I hear you Weezy, and while I agree, I'm an advocate for working a predictable small temp drift into your mash schedule. Much easier than eliminating it....

 

[Weezy]

I hear you Weezy, and while I agree, I'm an advocate for working a predictable small temp drift into your mash schedule. Much easier than eliminating it....

I can see that, but there is a purpose here. It's not useless. And everyone has their own process that works for them and that they enjoy. There are tons of variations of the brewing process, usually based around equipment.

How do you feel about the full automation guys?

 

[Sadu]

This thread is a prime example of how some homebrewers are compelled to complicate the process. What is so important about holding a precise mash temp to a degree? The enzymes are pretty smart and seem to easily figure the job out in my brewery? Let your strike temp dictate, and let the mash either fall or rise and mash within a temperature range.

I hear what you are saying, but that approach didn't work for me in practice. Temp drift was ending me up with FG finishing all over the place and beers would come out either too boozy or too sweet. I'm a firm believer that the best beer is made when the yeast finish in the target FG zone for the style. It keeps the recipe in balance.

I now use a PID controlled recirculating mash for my 1 gallon system and while it's the polar opposite of simple I really couldn't be happier. Simply put, my beers are coming out as I designed them. Also with 1 gallon batches, repeatability is an issue. If I brew a good one I'm gonna want to scale up to 5 gallons on my bigger system, so my recirculating mash helps maintain consistency between my 2 systems.

 

[Cainmos]

I can see that, but there is a purpose here. It's not useless. And everyone has their own process that works for them and that they enjoy. There are tons of variations of the brewing process, usually based around equipment.

How do you feel about the full automation guys?

Haha yeah who needs to actually make beer themselves!

I agree that we make do with what we have and can reasonably afford which molds everyone's process a little differently. For me it's about finding what works effectively and efficiently.

Wilserbrewer, I hear ya on KISS for that very reason. I do agree to an extent the enzymes are going to do their thing as long as you are in the correct temp range and not being within 1F the whole mash is not a problem. However, it does make a noticable difference if you can't maintain it consistently​. So that's what I'm aiming for and working for: a calculated or expected temp change over the mash process to be able to consistently produce.

I like all the ideas that have come up in this. They speak to the resourcefulness and problem solving ability within this community that I love.

 

[Cainmos]

At batch sizes under 2-3 gals it cant be beat. Above that, its underpowered. If you dont like the plastic in your mash just take the bottom cap off.

I dont do step mashing or anything fancy, but it still provides perfect temp control. Just keep your bag clear of the impeller and all good.

Wort scorching is not an issue in the mash. If you use it to maintain high whirlpool temps (185) you will get a bit of wort/hop burn onto element, but its pretty minor. But at typical mash temps, its not an issue ive ever had.

Thanks for the input! I definitely can't wait to try it out. I wasn't sure if part of the "food safe" thing was the type of motor seal used too. Will probably take the thing half apart when I get it anyway haha

 

[Cainmos]

Also with 1 gallon batches, repeatability is an issue. If I brew a good one I'm gonna want to scale up to 5 gallons on my bigger system, so my recirculating mash helps maintain consistency between my 2 systems.

This was my problem for a while until I became proficient as a human PID. But it isn't the best for what I want. repeatability is necessary to be able to scale up since I really will only make large batches if I can get them right on the smaller ones.

 

[Sadu]

This was my problem for a while until I became proficient as a human PID. But it isn't the best for what I want. repeatability is necessary to be able to scale up since I really will only make large batches if I can get them right on the smaller ones.

Yeah I'm bored with being the human PID. I like to do other stuff while the mash is going, otherwise the family gets snarky.

With my 1 gallon batches I can mill the grains, measure water, add salts the night before.
At afternoon tea break I set the HERMS to strike temperature and forget about it. After work it's at perfect strike temps, ready whenever I am, I dough in and begin recirculating. Then go make dinner and hang out with the family. After dinner if it looks like I have a 20 min window to sparge, all good. If not I set the HERMS to mashout temperature and leave it there until I get a chance to do the sparge, might be a couple of hours after the kids are in bed. Then sparge and boil, maybe play some computer games with the boil going next to me.

Everyone is different but for me the recirculating mash has taken out a lot of the babysitting work. 10 mins saved not having to get the strike temperature correct, don't need to check the mash temperature so often, don't need to stir, sparge water is ready to go anytime (since I recirculate through the sparge water), mashing out is easy if I need to do that, step mashes are back on the table again (I brew mostly lagers so this is useful). The electric HLT also doubles as a boil kettle which gets the brewing out of the kitchen, this means waaaaaaay less grief from the family. It was a fun project to build and total cost about USD$120 so not too bad really.

 

[Weezy]

Temp control really is the most critical part of mashing. It really does dictate how your beer ends up. Even John Palmer said in his book, in the water section, about how you only need to get within the 5.2-5.8 range for pH; is not critical, but temp is critical.

 

[Dcmpres]

For simplicity, when I do my 2.5 gallon biab batches. I preheat my oven with my pizza stone on the bottom of the rack. I usually set the temp 5-10 degree above my grain temp. When the pizza stone hits my temp, I place the kettle on the pizza stone, then turn off the oven. My temp has never dropped more than 1-2 degrees at the end of 60 minutes.

 

[C-Rider]

I do 2 gallon batches and mash in a 5 gallon cooler. I preheat and cover w/a few flannel shirts while I grind my grain and measure out my hops. A trick I picked up here is to cut a piece of cardboard the diameter of your cooler and cover it w/al foil. Place this on top of the water and it helps hold the head down where the water is. I BIAB and after placing the bag in the water I slowly add the grain mixing all the time. I then replace the cardboard on top of the wort and close everything up. Again covering the cooler w/flannel shirts. Today air temp on my deck was about 83* and the wort starting at 153 was 150 after 1 hour.