Low mash temps & low FG

I have been having trouble keeping a high enough mast temp and I think it is causing my FG to be lower than I would like. I have been mashing in at around 169* and getting a mash temp of about 152* witch isn't bad but over the course of an hour it drops a couple of degrees. I keep the lid on and don't stir as much as I would like as to not lose much heat. My beers have been coming out at 1.008 down to 1.001, much lower than I am shooting for. I am tempted to mash in at a higher temp, say 175 to get my initial mash temp up to about 156* or 158* even. This would allow for more time to stir and heat loss would be less of a concern. I have read that temps over 170* will extract tannins and that is undesirable. Would mashing in above 170 be that bad? Will this help my problem with low FG or am I looking at the wrong thing? I don't mash out as there is not enough room in my MLT, would it help to mash out? I currently use a 5 gallon round cooler for my MLT. I warm it with hot water first, then drain and add my strike water at a higher temp than I want to mash in at. I let the water cool until it hits 169 then add grain. Any help would be greatly appreciated.

Temps over 170 will denture enzymes, but they will not extract tannins unless your pH is seriously out of whack. If temps over 170 were a problem, no one could ever do a decoction mash. In a seminar presented at NHC last summer, Greg Doss of Wyeast had done an experiment that identified a mash temp of 153 as producing the most fermentable wort. Your 152 is darn close to that. If you batch sparge, a mashout will not help. If you fly sparge, it might.

I have found that over a 60 minute mash my temps will drop 3 or 4 degrees. Since I know this I will boil 6 cups of water and add it halfway through the mash bringing the temp up where it needs to be. Benefit also because I stir the crap out of the mash at that point.

Doing this I can keep the mash pretty much right on the whole mash.

Varmintman said:

I have found that over a 60 minute mash my temps will drop 3 or 4 degrees. Since I know this I will boil 6 cups of water and add it halfway through the mash bringing the temp up where it needs to be. Benefit also because I stir the crap out of the mash at that point.

Doing this I can keep the mash pretty much right on the whole mash.

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Interesting. Using my old cooler, I maintain within 1-2F for up to 90 min.

Sucks I tell you. My old cooler did a much better job at keeping the heat in but was just to dang big and I was getting stuck sparges. I went to a smaller new cooler and with the deeper grain bed I do not get stuck sparges but have to add water half way through.

I would much rather fight temps than fight stuck sparges. I will never forget the look my wife gave me the first time she came in and I had the hose in my mouth blowing the wort backwards through the manifold. Priceless I tell you

Have you tried a hose braid? Much less prone to stuck runoffs. 430 batches and I've never had a problem.

Thanks for the info Denny, so are you saying that mashing in higher than 170 will be okay? I do fly sparge so I might get 10 gallon cooler so I can mash out. I have read that 153 is an ideal temp and I know I'm close so, do you think this is causing my low FG or might it be something else?

Varmitman, I have thought about doing that. Do you just add the water at boiling temp?

kylebenton said:

Thanks for the info Denny, so are you saying that mashing in higher than 170 will be okay? I do fly sparge so I might get 10 gallon cooler so I can mash out. I have read that 153 is an ideal temp and I know I'm close so, do you think this is causing my low FG or might it be something else?

Varmitman, I have thought about doing that. Do you just add the water at boiling temp?

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I think it's something else, compounded by your mash temp. Have you checked yur thermometer calibration at mash temps? It could be way off. Yes, using water hotter than 170 is fine, although you don't want the grain temp over 170 or you'll denature the enzymes you need. Try calibrating your thermometer (NOT using the freezing water/boiling water method). Once you inow it's accurate, try mashing at 158 to see what happens.

Denny: I have the braid and everything I just have not swapped them out yet. Sigh ben meaning to do that for about 6 months now

Kyle: Yup over time I have found what works for me as far as volume. Start slow and stir like crazy though or you will end up with a hot spot and get a false temp reading. When I mash in I typically go about 12 degrees over my mash temp so a 153 degree mash I would heat my water to 165. I pre heat my tun though and add the water to the grain instead of grain to the water.

All in all it just takes time to learn your system and what works. What works for me might not work for you and your system. And bonus think of all the beer you get to drink fine tuning your process

FWIW, I don't preheat my tun. I experimented a bit and found that if my strike water is about 14-15 degrees hotter than my desired mash temp I can hit the temp spot on every time. Just saves a step. I put the water in the cooler and slowly pour in the grain while I stir. Just goes to show there's more than one way that works!

Denny, I am relatively certain my thermometer temps are correct. I have two lab thermometers that read the same. I have tested them in boiling water. I will test them again, what method do you recommend? I what do you think it may be if not mash temps. I am hitting all my other numbers, OG and proper volume. My efficiency has been in the 80s. I thought it may be high ferment temps but the last brew fermented at 62 for two weeks, I moved it to the secondary today and it was at 1.08. My target is 1.12, I know I'm now too far off but I plan on leaving it in the secondary for a couple of weeks and I'm sure it will drop further. Should I just bottle it now? Maybe i am leaving my beers in the fermenter too long? I and am brewing tomorrow and I will mash at 158* an see what happens.

Make sure both thermometers read the same at 150. Short of buying a certified lab thermometer, that's about the best you can do. Try a higher mash temp, like you said. And maybe try batch sparging. Remember, when you fly sparge you're prett much at mash temps all through the sparge. Maintaining those temps for a longer time means conversion is still taking place and long chain dextrins are being broken down into more fermentable sugars. When you batch sparge, you get tp a boil much more quickly and that isn't a issue.

I see, I will batch sparge tomorrow. I have never tried that, I have always fly sparged slowly. Sparging usually takes 1.5 hours. I am assuming that that is why you would mash out when fly sparging, to stop conversion? Thanks for all the help.

kylebenton said:

I see, I will batch sparge tomorrow. I have never tried that, I have always fly sparged slowly. Sparging usually takes 1.5 hours. I am assuming that that is why you would mash out when fly sparging, to stop conversion? Thanks for all the help.

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You are correct!

Denny said:

Make sure both thermometers read the same at 150. Short of buying a certified lab thermometer, that's about the best you can do. Try a higher mash temp, like you said. And maybe try batch sparging. Remember, when you fly sparge you're prett much at mash temps all through the sparge. Maintaining those temps for a longer time means conversion is still taking place and long chain dextrins are being broken down into more fermentable sugars. When you batch sparge, you get tp a boil much more quickly and that isn't a issue.

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Not sure how you know the 150 temp referenced above is 150 without measuring it with a calibrated thermometer. I have always thought that the reason one calibrated with an ice bath or boiling water was that you could assume the temperature value (after adjusting for barometric pressure). At my elevation water boils at about 210 degrees. Easy to calibrate to. I realize the advantage to calibrating at the target temperature but I don't get how I can verify such a temperature in order to calibrate my thermometers.

Cheers

beerguy52 said:

Not sure how you know the 150 temp referenced above is 150 without measuring it with a calibrated thermometer. I have always thought that the reason one calibrated with an ice bath or boiling water was that you could assume the temperature value (after adjusting for barometric pressure). At my elevation water boils at about 210 degrees. Easy to calibrate to. I realize the advantage to calibrating at the target temperature but I don't get how I can verify such a temperature in order to calibrate my thermometers.

Cheers

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You're absolutely correct. But I was saying that if both thermometers read 140 together, then that's the best assurance you can have short of a calibrated lab thermometer.

Sometimes I think that we'd be better off not relying so much on the accuracy of our instruments but making sure that they are reasonably precise. If I mash at say 154 as shown on my thermometer and the beer is good and is what I was shooting for who cares if the "true" temperature was 152 or 156 or a million. What I want is for that recipe to turn out well when my thermometer says 154. So it's very important that my instruments be precise. I am willing to tweak the recipe in my own environment as long as the experiments are reproducible. Same thing goes for all our measurements. I don't know for sure if the temperature value returned by the thermocouple inserted in the thermowell in my fermenter is at all accurate. But what I do know is that xyz wort fermented by abc yeast tastes great when that thermocouple maintains a temperature value of, say, 65. Don't know or care what the "true" temperature is.

And I do understand that an assumption of accuracy is what makes recipe/technique sharing possible. But what I want to be able to do is non-accidentally make a great beer and then be able to make it again. I want to be precise.

Cheers