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Temperature Control

Temperature Control

This month (May, 2022), Serge Savin gave us an overview of the many options available to home brewers to control the temperature of fermentation.

London Amateur Brewers

May 23, 2022
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Transcript

  1. Temperature Control
    S E R G E S A V I N / L A B / M A Y ‘ 2 2

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  2. Why?
    There is a temperature
    window for optimal
    fermentation, to produce the
    desired set of fermentation
    characteristics
    Fermentations occur
    exothermically, most often
    you would want to be cooling
    your fermentation
    Often, a particular
    combination of aromas and
    flavours is achieved in a very
    narrow temperature window
    (e.g. a hefeweizen
    fermentation is notoriously
    tricky)
    Off-putting aromas and
    flavours can be produced
    above particular
    temperatures, together with
    fusel alcohols
    Many yeasts stop working
    below a certain temperature
    and flocculate, leading to a
    stalled fermentation (that
    might need additional yeast,
    not only heat, to be restarted)
    During the growth phase,
    yeast can get stressed if the
    temperature is allowed to ‘run
    away’, often producing
    undesired esters
    High gravity beers already
    exert a lot of osmotic pressure
    on the yeast, making it work
    harder – akin to fermenting a
    couple of degrees higher
    More importantly –
    consistency and repeatability
    of that fantastic batch you
    made!

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  3. Heating – Very
    Simple!
    • Put the fermenter somewhere warm
    • Insulate – bubble wrap, thermal foil, sleeping
    bag, duvet, etc
    • Get a heating belt and a temperature
    controller (e.g., Inkbird - comes in handy with
    cooling too)

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  4. Cooling – Not
    So Simple!
    A multitude of
    methods
    From cheap and
    cheerful, to expensive
    and involved
    But – there is middle
    ground too

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  5. Level 1 – Become
    Friends with Nature
    • Brew seasonally – Belgian/saison in the summer,
    variety of ales during autumn and spring, lagers
    during winter, eisbock behind the polar circle..
    • Utilise spaces under the stairs, in the cellar, shady
    garden shed, anywhere the temperature is stable
    and on the cooler side
    • For years I used a wardrobe because no matter the
    temperature fluctuations in the room, it always
    stayed roughly the same
    • My mixed-ferm is still at whatever the room temp is
    • You are at the mercy of a weather shaman

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  6. Level 2 – Bucket in
    a Bucket
    • Keeps things cool
    • Needs manual temp monitoring
    • Fill up with cold ground water and/or (ideally) ice
    • Temp fluctuates up and down
    • Lacks precision

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  7. Level 2.5 – Dressed
    Bucket in a Bucket
    • Keeps things slightly cooler, benefitting from
    evaporation off the cloth
    • Needs manual temp monitoring and top up from
    time to time
    • Fill up with cold ground water and/or (ideally) ice
    • Temp fluctuates up and down
    • Lacks precision

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  8. Level 3 – Dressed
    Bucket in a Bucket
    with a Fan
    • Keeps things even cooler, benefitting from
    evaporation driven by a draft
    • Needs manual temp monitoring and top up from
    time to time
    • Fill up with cold ground water and/or (ideally) ice
    • Temp fluctuates up and down
    • Lacks precision

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  9. Level 4 – Insulate
    with Frozen Saline
    Solution
    • The largest cooling contribution comes from the transition between
    states of matter, pure water freezes at 0C, saline solution below that
    • Heat capacity depends on the state of matter, need to consider:
    • Heat required to bring up to melting point
    • Heat required to transition from solid to liquid
    • Heat required to bring up to beer temperature
    • Modelling the total heat capacity offered by saline solutions of various
    strength by weight, 15% was the sweet spot, freezes around -11C
    • 6x2L bottles – 4 in use, 2 in the freezer, swapping 2-3 times a day
    • Surprisingly effective, rarely had temps running away
    • Needs constant attention and still lacks precision

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  10. Level 5 – Spend Some
    Money: Submerged
    Cooling Coil
    • Many off-the-shelf kits (most notably SS Brewtech) with a stainless-steel
    coil that is submerged into the beer, with coolant pumped through
    • Some include heating pads as well as a controller
    • Allows to precisely set temperature
    • Can save money and go DIY, that Inkbird coming handy again
    • Requires a thermowell to measure temp
    • Still have the task of chilling the coolant, but can submerge the pump in
    a picnic cooler with water/ice or those bottles filled with saline solution
    • Still need to swap out frozen bottles 2-3 times a day
    • A lot of faff with multiple components and cleaning, not worth it in my
    view

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  11. Level 6 – Copy the Pros:
    Get a Jacketed
    Fermenter
    • Some come with an inbuilt controller and heating
    pad, e.g., Grainfather Conical that let’s you
    program temp schedule
    • All the advantages of the submerged coil and
    none of the faff with cleaning
    • The same problem of chilling the coolant
    • Expensive

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  12. Level 7 – Spend Some
    Money: You Need an
    Extra Fridge!
    • For little money you can pick up a second-hand fridge (try to get an
    energy efficient one)
    • Multiple ways to control – PID, BrewPi, BrewPiLess, etc. but the simplest
    and cheapest is Inkbird
    • The fridge turns on when the temp needs to be cooled and turns off
    once the target is reached (or you can connect a heating belt/pad)
    • Note that fermentation temperature in the middle of the FV will be
    higher than the ambient in the fridge by ~1-2C
    • Can cold crash and lager
    • All fermentations at the same temp or need multiple fridges
    • Needs a bit of space but works a treat!

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  13. Level 8 – Raid the
    Aquarium Store
    • Same setup as a submerged coil/jacketed FV
    • Replace the picnic chiller with an aquarium pump
    in a closed loop, with a vessel for the pump
    • Picked mine up (Hailea HC100A) used on eBay for
    ~£120, just need to look out for deals
    • All the advantages, plus set and forget
    • Allows to precisely set temperature, saves space
    • Can chill down to 8-9C on my setup, even during
    fermentation, 2C higher in the summer
    • Loud – wouldn’t be able to sleep in the same room

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  14. Level 9 – Go Big or
    Go Home: Glycol
    • All control you could possibly want
    • Most glycol chillers can sustain several fermenters
    at different temperatures
    • Many options on the market, size/power/cost
    • Take less space than multiple fridges
    • Super expensive or you just need to win Lager
    Than Life after brewing an awesome beer using
    one of the other methods!

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