Mash temperatures

[buzzrtbi]

Made another AG brew at the weekend and found something interesting (probably not to many of you folks).

After doughing in the grain I took a temperature reading from the middle of the tun (thrust the probe deep in) - happy the temp was 66 degrees.

a while later I checked with the probe all around the mash and got dfferent temperatures from the edges, middle, top & bottom. Is this normal - I suppose it must be thinking logically. After all you get different temperatures in ovens and fridges etc.

What was concerning from this was the middle of the mash was now higher than 66 degrees whils the edges were maintaining it?

I did not have an element on or anything like that?

I gave the mash a stir to equalise the temperature out.

I guess it must have been doing this all along, I dont usually take spot temperatures from all around the tun, usually just leave the probe dangling in the centre with an alarm set to go off if it drops below 65?

any thoughts - spontaneous combustion perhaps

[buzzrtbi]

When you dough in, you should thoroughly mix the grain to ensure there are no temperature differences in there but by preheating your mash tun thoroughly you will reduce the chance of temperature differences in the mash. Generally the grains on outer edges of the mash willl get colder if the mash tun hasn't been heated properly (ie it is colder than the desired mash temperature). You can preheat it with a couple of kettles of boiling water but I prefer to fill it with the mash volume at 80 deg and allow the temperature to stabalise, usually at around 72 deg by the time i've prepared everything else. Small adjustments can be made using boiling water or cold water just draw off what you add.

Hi Daab, thanks for the reply. Funny thing is - I did all that you suggested above. I heated the mash tun up, I doughed in like a man posessed (I always do to ensure I dont get a stuck mash). I tried the temperature all over and this is what I found!

Granted, I do have a fancy new digital thermometer & probe so was fiddling with it - stabbing about testing when I found this?

I am happy with this tun - it is a heavily insulated burco with bottom tap - insulated all round including the lid.

cant understand why the temperature rose in the middle - when I gave it a stir it was fine - no lumps.

Not too worried about it - it mashed well and has a good yeast head on it now. SG was spot on etc. just wondered if anyone else had found the same?

[maxashton]

I have a fancy digital thermometer, and it has a rather interesting idea of temperature at times. On one occasion, it was telling me water was boiling at 92 degrees C. I'm not high enough above sea level for that to be the case!

[buzzrtbi]

exothermic reaction - thats the word I was thinking of !!

thanks for the replies

[Jim]

I have to say that I generally get different readings from different parts of the mash. No more that a degree or 2, though.

[Gurgeh]

HERMS!!!!!

sorry DaaB!

[Jim]

HERMS!!!!!

sorry DaaB!

[Stonechat]

HERMS!!!!!

sorry DaaB!

INSULATION!!!!

no worries Gurgeh

Have enjoyed the good-natured banter, but is it possible to have the pros and cons put forward from each side, please?
Also, is the HERMS system used by commercial breweries?

[Aleman]

Is the HERMS system used by commercial breweries?

No, they are too relaxed and chilled out to be worried about a little bit of variation in the mash tun . . . . plus the thermal mass of the mash in a commercial tun is incredible. Using a Steeles masher (Archimedes screw type thingy) to mix the liquor with the grist from the 'heated' grist case does a pretty good job of getting an even temperature, and a degree or two either way isn't that important.

[Stonechat]

Is the HERMS system used by commercial breweries?

No, they are too relaxed and chilled out to be worried about a little bit of variation in the mash tun . . . . plus the thermal mass of the mash in a commercial tun is incredible. Using a Steeles masher (Archimedes screw type thingy) to mix the liquor with the grist from the 'heated' grist case does a pretty good job of getting an even temperature, and a degree or two either way isn't that important.

Thanks for the reply Aleman. Why do some of us amateurs want to use HERMS then, especially if efficient insulation can keep the mash temp. to within 1 or 2 degrees over the 60 or 90 minute mash?

[Aleman]

Why do some of us amateurs want to use HERMS then

Boys toys , once scaled down to homebrew sized volumes heat stability of the mash is significantly reduced (as demonstrated in the first post). There are very simple measures you can make/take to improve this such as insulation and preheating . . . but its great fun to over complicate a simple solution.

We Choose to do these things, in this decade, not because they are easy, but because they are hard!

[Stonechat]

Why do some of us amateurs want to use HERMS then

Boys toys , once scaled down to homebrew sized volumes heat stability of the mash is significantly reduced (as demonstrated in the first post). There are very simple measures you can make/take to improve this such as insulation and preheating . . . but its great fun to over complicate a simple solution.

We Choose to do these things, in this decade, not because they are easy, but because they are hard!

Again thanks for that. I must admit to being intrigued by the process and terrified of the technical aptitude to make it work. I think I'll stick with my thermobox, which I'm delighted with

[Gurgeh]

my reason for wanting to go down the herms route is largely due to wort clarity.

in terms of difficulty in manufacturing the herms, my solution is a very simple reconfiguration of kit that I already have.

I already have a pump, a spare IC and a temp controlled HLT.

I need to make a return manifold like Seveneers:


this will take 20 minutes to create...

the plan is merely to slowly pump the wort out of the bottom of the mash, through the IC in the HLT and back into the tun. There will have to be a little recirc loop across the inlet & outlet of the pump so I can control the flow rate, but very easy to do.

can't see any harm in it

[Oggy' Bar]

I need to make a return manifold like Seveneers:

Is that seveneers return manifold? if so, I presume it is buried just below the mash and the returned wort is gently fed through the upright 15mm tubes, is this correct?

How is the manifold prevented from sinking into the mash? is it held suspended?

How is the manifold maintained level to ensure the wort issues from each orifice to maintain a stable temperature and flow throughout the mash?

[Gurgeh]

Is that seveneers return manifold? if so, I presume it is buried just below the mash and the returned wort is gently fed through the upright 15mm tubes, is this correct?

How is the manifold prevented from sinking into the mash? is it held suspended?

How is the manifold maintained level to ensure the wort issues from each orifice to maintain a stable temperature and flow throughout the mash?

yes
I believe it's a 'H' shape and the returning wort is coming down the central hose, which also suspends it.

last question - i suspect it 'just does'...