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Residual heat and strike temperature.

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  • Residual heat and strike temperature.

    Since outside of Denny's advertising, not much seems to be going on here as of late, I thought I might pass on a little tip to those who haven't already discovered this emperically, or find it intuitively obvious.

    Most home brewer's discover a personal schedule where a certain volume of malt mixed with a chosen volume of water and strike temperature, gives them a predictable mash temperature. You might have to adjust for e.g. seasonal variation in the temperature where you store your grains, or you might want to change the dilution of your grist, but sooner or later the seasoned brewer susses such things out.

    One thing that might happen if you don't have a temperature control on the strike liquor when heating (as I do not), or if you tend to do several things at the same time and, "forget" things, and if you are heating your strike water in your mash tun to add your grains to, is... well you might overshoot your temperature.

    One might think that is an easy thing to fix. Just let out a little water, and add some cold. Right?

    What I am saying here may be obvious if you think about it, but if you haven't.... here goes!

    A strike temperature of say 76C on the way up, is NOT the same as 76C on the way down!


    There is a lot of residual heat in your mash tun itself. Depending on the material, the wall thickness, the geometry, and how well it is insulated.... it can be quite a bit.

    So, say you have overshot your strike temperature. You let out water, and add cold. Now the thermometer in the water may say that you are at the correct temperature, but if you mash in straight away, you will overshoot your mash temperature, as the residual heat of the tun itself warms it up. In my case it would be a matter of about 4C plus (depending on just how sloppily I ignored my temperatures, or how engrossed I became in something else while brewing), and I have to "overshoot" my cooling to compensate for that before I chuck in the grains.

    As I said, this is of course obvious once you've figured it out, but if you haven't yet, perhaps this little tip will keep you from getting surprised.

    On the other hand, a dextrin-rich, low alcohol beer can be kind of fun too, and commercially a so called "jump mash" is doing just that. Hopping up to 70C to create low alcohol beer with full beer flavour.

    I like making some of those in the summer, when the consumption rate increase logarithmically.

    As a brewer friend put it: "Sometimes we like to get drunk. It can be fun. Sometimes we don't. But we ALWAYS want to drink beer."

  • #2
    You have an unusual definition of advertising.


    • #3
      Originally posted by denny View Post
      You have an unusual definition of advertising.
      No, Denny. I have the usual definition of advertising. As a noun? "The activity or profession of producing advertisements for commercial products or services" As a verb? "describe or draw attention to (a product, service or event) in a public medium in order to promote sales or attendance-

      You have a blog. This is just a modern term for a "radio show" if only audio, and a television show if video is included.

      You have sponsors. They give you goods or services or cash. And in return for that economic remuneration, you promise to spend a certain amount of time on your show, saying nice things about them. That is nothing new, and has followed on all commercial radio and TV sendings.

      So you have a commercial site supported by advertising. That satisfies perfectly the definition of the noun You then come on here and advertise your blog. Naturally if your listenership goes up, so does the value of the spot time on your show.... you attract more sponsors and can charge more per unit time from the existing ones. That's how commerce works. Now we have satisfied the verb.

      Now there never seems to be more that about 15 people who ever even look at your stuff. I'm assuming it's mostly the same individuals. Why not just make them subscribers and be done with it? Because you are ADVERTISING for more listeners.

      If you look at the number of people who have followed, say, the "cooling" thread it is over 1,500. That means there one hundred times as many people interested in reading that, than there are folks who like looking up your blog.

      And yet you consistently cover, from your one percent interest rate, 60% of all postings! You have single handedly rendered this service "unarchivable". If I read something of interest, and think about it awhile, it may be a few weeks before I have consolidated my thoughts on it.... maybe looked up a few references, and when I turn back here to respond.... it's gone! It's been bumped to page 2 or 3, because the whole thing is filled with clones of some guy in an aloha shirt abusing a ukulele.

      I shall put word "advertising" in a grammatically, and factually correct sentence. As a noun: "Denny likes taking about making beer, and really likes advertising", As a verb (I think this would be the "present active participle form of the verb "to advertise"): "Here comes Denny, advertising again."

      So you see, I have quite the "usual" definition of advertising. Perhaps YOU have an unusual definition of the word....

      or perhaps you just have an unusual manner of interpreting your own behaviour.


      • #4
        Interesting point Dr. Pivo. Never gave it much thought as I rarely overshoot my strike temps, and when I do it’s by a few degrees and some swift stirring gets it to where I need it. Luckily I have a direct fired system so I’m usually cautious and undershot as I can add heat easier. Never really thought about allowing time to stabilize if adding water. Good tip!


        • #5
          Loopie. Most of the interesting stuff I've learned about brewing, is by making mistakes.

          I just figure that everybody else doesn't have to make the same ones. Once (or several times), by me should be enough.


          • #6
            Loop! Just some additional thoughts on the topic. I assume you are firing with propane? In that case this is even more important to consider if I am figuring this right. Follow my logic and see if this seems right.

            You are heating the bottom of the tun. which in turn heats the liquor (water). That heat goes from the liquor to the walls of your tun. The outside material in your tun walls will by necessity be cooler than the liquor itself (it's heat conduction which lags behind the material it is getting heat from). So when you mash in, the walls of the tun will be "robbing" heat from the mash until stable.
            Now that makes absolutely not a wit of difference when you by experience know where it will end up.
            On the other hand, if you've overshot, and add some cold water, then the tun walls are actually warmer than the liquor, and they will "add" heat.
            The quicker your heating system, the larger the differential between liquor temperature and tun walls will be, and the more the tun itself will rob temperatures.
            Conversely, if you "overshoot" the differential will be greater there, so it won't add as much heat.
            Where you would get into problems here, would be if you grossly overshot your temperature (done that many -a-time) or if you changed your work habits, and instead of striking when you hit your temperature, you decided to let it sit at that temperature for quite a while (I gone and done that many-a-time too....duh.)
            Then you would need to bring your strike temperature to lower than you're accustomed.
            I'm sure some engineering whiz in thermodynamics could tell you exactly how much according to time and temp.
            That's too big a problem for me to even contemplate solving it.
            As I said, I tend to do several things at once. I start heating the strike water, and then I go crush my grains. If I meet a neighbour at the crush, or I find out I need a 3-phase extension cord, and return for that, or my dog decides that she just has to start digging up sorks in the field, and has her head stuck underground sniffing them out, so she doesn't come to go when I call her..... well the temperature just sort of ends up being whatever it is when my wandering attention span puts me back in the game.
            By screwing it up enough times, I've learned pragmatically just how much I have to then cool under my usual strike temperature in order to get the same mash temperature.
            And once aware of this fact, I'm sure you could too.


            • #7
              er, sorry. Language fart. "sork" is a "meadow vole" in English, and my dog just loves diggin' 'em up.


              • #8
                First thing I tell new brewers is to figure out THEIR system. Each system has its quirks which once figured out allows repeatable results. With my system, if I’m doing a step mash, I stop adding heat a few degrees before reaching my desired temp as I recognize that the mash will continue to heat.
                One nice thing about a direct fired mash tun is that the pot heats as you heat the water which takes out a lot of the variables. I dint suffer from adding hot water to a mash tun and have to figure that loss in addition to grain temp losses. On average I lose 5°f when adding grain.


                • #9
                  The Loop wrote:"First thing I tell new brewers is to figure out THEIR system. Each system has its quirks which once figured out allows repeatable results."

                  True that, bro'.

                  It IS important to be able to make ONE good beer, before jumping into sixty-eleven different recipes. Getting the mashing, sparging and boiling part down doesn't take so long. And then comes the fermentation...... well, on that one, I'm still in the baby stages.... and I've been doing it for over 40 years.


                  • #10
                    Haha! I agree with the mash and sparring process. Doesn’t matter if you do it “right” or “wrong” as long as you do it the same way every time! In all seriousness I think efficiency is over rated in the homebrewing scene. If your process is working but your seeing only 75% efficiency vs. 80% a little extra base malt goes further than spending a lot of money on re-working your system. And again, getting 75% consistently is better than getting 75% then 80%, then 60%...

                    I often tell new brewers to brew the same beer a few times in a row to get your process down. Once you do that you can experiment a little more as it will be easier to tell if there was a processing error or an ingredient error.

                    In regards to fermentation, temp control is the most important, as you know. I equate it to buying the best ingredients for a pie and then popping it into an oven at 500°. Doesn’t matter your process or ingredients, it’s not going to turn out well.


                    • #11
                      Wise words Loop. I think the "brewhouse efficiency" can be a matter of false pride when you first start out. Consistency is more important. Once you "know" what the results will be, you can start fiddling with stuff. When I'm in "that" mood, the only thing I measure is the strike temperature. I know what the OG and FG are going to end up as, so why bother measuring it for the 500th time.

                      I am VERY big on temperature control during fermentation. When and how much you introduce oxygen is another sensitive parameter, and then there is whole carload of other issues. I am still messing around a LOT with that. I already have several primary fermenters to deal with the same brew. Why not split my procedures up and try different stuff?

                      In short, if cost efficiency and long shelf life are your goals in brewing you will drift more and more towards commercial practices. The disappointment in tasting those, as opposed to the products of small, traditional, and actually quite primitive breweries, that have a predictable turnover and don't NEED long shelf lives, has been the main driving force behind my development as a brewer.

                      Other folks might want something else from this (for me, quite obsessive) hobby, and they are welcome to that.


                      • #12
                        Unfortunately I don’t have much time to dabble in experimental brewing anymore. With brewing test batches I need to focus on ingredients, consistency, and stability.
                        I totally agree in taking the hobby where you want it to go. Sadly I think many in the hobby are obsessive like you and I. I think people who aren’t only brew a couple times and discover they don’t want to put in the work. After all, it’s easier and cheaper to buy beer.


                        • #13
                          I admire your tenacity, Loop. I have met many micro-brewery brewers who still have a fun time, enjoy what they are doing, and retain their enthusiasm for it. I really enjoy helping them when they have system problems, but I'm afraid if I got myself seriously in the game, and had a required production schedule, and a need for repeatable results, I might well lose my child-like enthusiasm for the hobby. I swing from periods of extreme,
                          pedantic exactness (usually when I'm trying to figure something out) to times when I don't even weight the hops... a sort of: "That looks about right" attitude".
                          Even in my sloppy times, that is usually not a problem.... but during the world cup in soccer in Brazil (2014?), I cracked a new beer.... lovely as it almost always is, and after three pints I was falling off the couch!

                          I thought "Holy crapoly! Wonder what the OG on THAT one was, and how I managed that?"

                          Ended up buying crates of 2.1 ABW beer as a "mixer" so I didn't kill myself. The world cup lasts about 2 weeks, and I wanted to at least remember who won!

                          And it would be downright sinful to watch the entire world cup without steadily having access to a well brewed pint