Curious about my mash temps....

[J-Pizzel]

My mash temps have always varied wildly. Too high, too low, all over the damn place. It's been a couple months since I've brewed and its gotten me thinking- my thermometer is a probe at the end of a stainless steel wire. I've read recently that if water goes above the probe, it can come down inside the probe, screwing up its readings. I suspect this is what's causing my consistently low OGs. Therefore, I should set it so only the probe is submerged. Any input on this train of thought?

 

[J-Pizzel]

I currently use a 10 gallon Rubbermaid cooler with a stainless steel mesh tube. Have experimented with both mash and sparge, never hitting my numbers.

 

[choosybeggar]

Do you pre-warm the mash tun? Do you have an analog thermometer to compare? How much variance in temps are you getting (like 165 when you aim for 150 or just a couple degrees off)? Always high? Always low? How do you calculate strike water temps/volumes? How do you measure strike water volumes? Can you post your numbers from a recent brew (amount grain, amount strike water, temp strike water, planned mash temp, and measured mash temp)?

That ought to get the ball rolling.

 

[billl]

If you are taking notes with your volumes and temps and still are all over the place, I'd suspect your thermometer isn't working right. It should only take a batch or 2 to determine how many degrees you lose to your setup.

If you aren't taking notes and being consistent, then I would suspect "user error."

 

[Cap'n Jewbeard]

I had never heard that issue about the temp probe, but if it's true it's fascinating. I use the same probe, and I also have weird temperature issues in mashing.

(Also, I use it while boiling, and one thing that happens is that it will routinely show the wort at over 220 degrees F before any actual boiling happens).

J-Pzzel, I have the same mash setup as you (10-gal cooler w/ mesh tube). Pre-warming the tun is a huge help in limiting your initial heat loss. (Just put a couple gallons of pretty hot tap water, even, and put the lid on, then slosh it around a little and let it sit for 5-10 mins). When I did this I found my heat loss at dough-in was exactly what the recipe predicted (about 7 degrees), rather than losing much more to the walls of the tun.

To add a question to this: Can I just use a straightforward formula/ratio to when calculating how much water and at what heat to add, when aiming for a particular temperature?

For example, using numbers from yesterday's brew: I had about 11 quarts of 122 F mash in the tun, and I added back about 4 quarts of boiling (212F) decoction. I was aiming for 152.
According to the weighted average, this would raise the average temp of the mash to 146 (still too low), and in practice it went only to 140. So really, I should have added at least 5.5 quarts of boiling mash, and to be safe maybe 6 quarts.

 

[EyePeeA]

See the third and fourth posts in the following link for a better handle on hitting your mash temp: https://www.homebrewtalk.com/f36/do-not-fear-all-grain-brewing-primer-247631/

 

[Cap'n Jewbeard]

See the third and fourth posts in the following link for a better handle on hitting your mash temp: https://www.homebrewtalk.com/f36/do-not-fear-all-grain-brewing-primer-247631/

Holy cow. That is some good stuff. I know what I'm reading the next few days...

(I tried to like your post but I think the Like button doesn't work for me).

 

[cabron99]

Had the same problem with digital probes. Got an analog floating dairy thermometer ($5). End of problem.

 

[Cap'n Jewbeard]

Do you find that the temp at the top (where the thermometer floats) is a good representation of the rest of it? Maybe you just have to stir well to take care of it?