where does the thermometer GO?

made a great find on Ebay -a mash tun (Stainless 7 gal pot, with SS valve (welded) AND SS false bottom -for about a hundred bucks, new in box. )
I'm ordering up a brewmometer, but I'm not sure where to put the thing -should I put it below the false bottom, or above it (in the grain bed) ?
My eventual goal is to have this thing be a recirculating heat exchange infusion system, so my assumption would be that having the probe under the false bottom would be fine, since the liquid would be in continuos circulation, the temp reading should be correct for the grainbed. Initially, however (due to expenses) this probably won't be a recirculating tun. Any advice?
if this weren't going to be a recirculating tun, where should the probe go?

In everything I've seen, the thermometer and any thermowells for probes are above the false bottom. That allows you to read the temperature of the grain bed. It also lets you stir the mash to make sure that everything is well mixed and uniform in temperature.

I got my kettle from MoreBeer. They install the thermometers and thermowell holes at the same level.

http://morebeer.com/images/thumb/phpThumb.php?src=/product_images/morebeer.com/1/7056.jpg

where does the thermometer GO?

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That depends... is it a rectal or oral?

ChshreCat said:

That depends... is it a rectal or oral?

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I've been eyeballing this thread waiting for this one....:rockin:

funny you should mention the oral vs rectal.... my professional career (ie the money maker) is as a registered nurse. I used to ask my patients (while taking their temps) if they knew the difference between the rectal vs oral thermometer probes. (for those who don't know, one is red, the other blue)
When a patient would say "what is the difference?" I'd answer "the taste!" :>

Ok, I can see the point of monitoring with the probe in the actual grain bed -do you still stir the bed if its a recirculating infusion system? I had been leaning toward putting it below the false bottom mainly to keep it out of the way of the screen when I lift the screen to clean the system. OTOH I have noticed that the mash tuns that come with bulkheads pre-installed, they seem to have the thermometer bulkhead about a third of the way up the side (well above where any false-bottom would be).

Since I want to make this a HERMS, I was just wonderingif my reading would be more accurate by just reading the temp of the liquid under the bottom (as its always ciculating through the grain bed).

ChshreCat said:

That depends... is it a rectal or oral?

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Instant Rimshot

I don't stir constantly during the mash. I only really stir for a few minutes after adding the grain to the strike water to make sure the grain is fully integrated and that there are no dry spots or clumps of grain.

In my opinion, you'll still want to have the thermometer above the false bottom to measure the temperature of the grain bed. The wort being recirculated and the grain bed itself can have different temperatures at different parts of the process. You are more concerned with the temperature of the grain bed, not the liquid that is allowing you to increase, decrease or maintain the grain bed's temperature. When I mash out, the liquid going in to the mash is close to 175 degrees, but the grain bed is not.

It seems like measuring only the liquid could be inaccurate. With one or two degrees in the mash temperature making a noticeable difference in my finished beer, I want to be as exact as I can. Others may disagree however.

twst1up said:

Instant Rimshot

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I am not sure it is politically correct to put "rimshot" and rectal in the same post, but who am I to say.....

But regardless, I would put it 4 or 5" off the bottom so you get a more accurate reading, especially if it will be direct-heated at some point.

Important reminder for those of you that direct fire the MLT. Turn the heat off and leave it off before voraluf. The temp can rise to the point of disturbing the grain bed(without it rising on the thermometer) and allow the flour to come through. This is most important for flyspargers who only voraluf once.

thanks to all of you who wrote in on this. I'll put the bugger above the false bottom -you're absolutely right -I want to know the temp of my grains, not the wort under it. I just thought that with a continually circulating system the wort temp would equate that of the grainbed -if this isn't necessarily the case, however, then I could certainly be off in my temps and not realize it. Don't want that.
I'm putting a sight tube on the side of the MLT as well -figure it will be dead useful during sparging.
Ording the rest of the things I believe I need, and expect (not this weekend, but next) to spend the weekend drinking homebrew and building my rig, testing it with some old grains I've got laying around (or if I REALLY feel up to it, I'll swing by the HBS and pick up enough to do an inaugural brew) -depends on the time left and how I feel after putting all the things in their respective places.
I've read everything I can get my hands on about all-grain, and even though I'd really like to see it done once first, I think I'll just go ahead and do it.
Feels kinda giddy. Like the first time I brewed up an extract and partial grain batch (grin).
Hell, I'm just excited to be able to take it to the next level. Eventually I'll make a better stand for the pots and burners -but initially it doesn't have to be pretty, just very sturdy and safe.

Steve Martin, sitting in the bathtub singing to Bernadette Peters in "The Jerk"

Oh, I'm picking out a thermos for you
not an ordinary thermos for you
but the extra best thermos you can buy
with vinyl and stripes and a cup built right in

I'm pickING out a thermos for you
and maybe a barometer too
and what elsle can I buy so on me you'll rely
A REAR END THERMOMETER TOO

When you get to the point that you are going to recirculate through an external heat exchanger, you will want to measure the temp after the the Heat exchanger. More than likely though, you will leave the thermometer you have now in your mash tun and when you add the heat exchanger you will have a LOVE or RANCO probe measuring the temp after the heat exchanger.

Linc