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Measuring mash temperature

Post #1 made 9 years ago
by onkeltuka
I've done four brews now, and it's coming clearer with each one that taking temps is a very complicated issue.

So, you have a large kettle with a bag full of grains in it, the whole mass is heated from the bottom up, but in between there's that large layer of grain. So when you want to mash at 66, where do you measure that from?

In all my brews the temps have gone down a few degrees more after adding the grains, than what the BIABicus calculates. After that I turn the flame on again to bring the temp back up. I've started taking liquid out from the tap, which drains from under the grains, and adding that back to the top. Still, I feel that the temps at the bottom may be well over 70 at this point, and on top they may still be 64 or so.

After it settles out finally to a nice agreeable temperature, then it's usually been smooth sailing for the rest of the mash. Should I just go a couple of degrees higher before adding the grains? Off course ambient temperature (at which the grains are usually as well) affects this.

Last weekend I also encountered a new problem when brewing the 1.113 OG barleywine: after mash I turned the flame on again to raise the temps to mash-out. The mash was so thick that the temperature inside the bag didn't rise at all, but suddenly the sweet liquor outside the bag started boiling! At that point I just lifted the bag, and proceeded without a mash-out.
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Post #2 made 9 years ago
by joshua
OnKeltuka, A strong spoon, or Potato Masher, or a Concrete mixer tool can be used to Stir the Mash, depend on size.

Stir the Mash a few times to mix the grains and water..The temperature will be even thru the Mash.

Stirring will also help break up, "Hot-pockets", as well as the Enzymes to break down the Starch.

Stir, and Stir Often. is a thing to remember.
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Measuring mash temperature

Post #3 made 9 years ago
by Contrarian
In a big pot it is the thermal mass I the water that will keep your temperature even over the mash. If the temperature has consistently dropped more than anticipated over a few brews then I would aim to compensate for that prior to mashing in rather than after. I also like to give the water a good stir before testing the strike temperature to make sure it is relatively even.

After that I mash in I take a temperature that is normally within 1 or 2 degrees of my target and I leave it at that until mash out. Over 90 minutes I have never lost more than 3C. I then give it a big stir while ramping to mash out.

I have a good mate who has a 3V system and he has found temperature variations of over 5C in his mash tun and he makes fantastic beer.

There will always be temperature variation during a mash but this is more stable in full volume mashing due to the high specific heat capacity of water. The important thing is that small variations won't make a noticeable difference to your finished product.

Stirring often might help a bit but I'm a lazy brewer who is often using that time to play with the kids or do something in the garden so I've never found out!

Post #4 made 9 years ago
by mally
See this here Onkel.

A masher is the way to go.
Up & down, not round & round!
Last edited by mally on 08 Oct 2014, 19:33, edited 1 time in total.
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Post #5 made 9 years ago
by PistolPatch
Short on time but this might help as well.
onkeltuka wrote:So, you have a large kettle with a bag full of grains in it, the whole mass is heated from the bottom up, but in between there's that large layer of grain. So when you want to mash at 66, where do you measure that from?
RULE: You must always agitate/stir the mash before taking its temperature otherwise you are just measuring a pocket (as Contrarian mentioned.)
onkeltuka wrote:In all my brews the temps have gone down a few degrees more after adding the grains, than what the BIABicus calculates...
Read some of the posts here until you find info on heavy equipment and radiation. Use Section . Use the Strike Water Temperature Adjustment Factor in Section X to adjust for your equipment which I suspect is electric and/or light. I.e. Increase the adjustment factor.
onkeltuka wrote:Last weekend I also encountered a new problem when brewing the 1.113 OG barleywine: after mash I turned the flame on again to raise the temps to mash-out. The mash was so thick that the temperature inside the bag didn't rise at all, but suddenly the sweet liquor outside the bag started boiling!.
RULE: You must never apply heat to your mash unless you simultaneously agitate the wort so that no one part can get hot/boil*. The potato masher /paint stirrer (brought to homebrewing back in 2006 by me - how boastful :lol:) is perfect for this.

:peace:
PP

* For longer heat applications such as mash-out or temperature steps,if you have a pulley, you can raise the bag so that it is well above the bottom of the wort or even out of it. Occasionally lower the bag back into the wort (or deeper into the wort) and agitate the grist using your paint stirrer in the BIAB bag.

A false bottom does not solve the problem though it will stop your bag from burning. For similar reasons, raising the bag a little in narrow kettles will not solve the problem whilst in wide ones it will. Not sire if I've explained that enough but I am out of time now.
Last edited by PistolPatch on 08 Oct 2014, 20:28, edited 1 time in total.
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