Problems hitting mash temperatures

[Smitty27]

I've been having some issue hitting the correct rest temperatures when mashing. I recently moved from BIAB to a cooler and the first attempt I missed the rest marks on each one. I figured it was because I didn't compensate for the altitude I live at. So instead of adding boiling water that was supposed to be 212F it was probably only around 204F. So this time used the infusion calculator on the website and compensated for a 204F boil and still missed each temperature.

Strike Water: 14qt. 142F and it dropped to 128F - Shooting for 130F
Infused boiling: 12qt. @ 206F - raised to 152 - Shooting for 156F
Infused boiling: 10.5qt @ 206F - raised to 158 - Shooting for 168

The calculator each time told me lower temperature and quantities each time. Is there something else I need to be adjusting for so so I can hit the proper temperatures?

The good new is that I finally have my RaspberryPi up and running with two temperature sensors. Once that monitors the internal fermentation
temperature and the other monitors the ambient temperature.

 

[Nosybear]

I'm having similar problems using the calculator in my 65° basement. Last summer when I was working outside, it was dead-on. Heat loss was much lower as well. So I'm going with the calculator as guidelines - have some boiling water ready to bring up the temps or some cool water to bring them down. No simple equation can cover all the variables of cooler insulation, heat loss, ambient temperature, etc. Explore and discover and you'll find the right temps eventually.

 

[Smitty27]

The issue is that I don't want to end up with too much water in the boil kettle afterwards. Right now when I boil for 90min I only boil off 1 gallon and I don't want to end up boiling for 3hrs. I don't really lose much i the mash tun at all. In 30min with it being 22F outside I may have lost 1 degree but I don't even think I lost that much. It seems like the thinner the mash the harder it is to raise the temperature.

I started the mash at 1qt/lb, should I drop this to .5qt/lb to compensate for the larger additions towards the end to hit 168F?

 

[Ozarks Mountain Brewery]

one thing to note, I have been messing around with different temp probes recently and found a huge difference in readings between some and the pid or arduino I use, you might want to compare and find the correct probe before moving to the mash temp being wrong, some of mine were as much as 4 degrees off

 

[Smitty27]

Sorry, I probably wasn't clear about that. The probe is only for my fermentation temperatures. When I'm mashing I compare two thermometers to see if I get any difference. There is one that sits in the mash and moves really slowly but seems to be accurate and another one that takes reading much faster. The sensor is a DS18B20 water proof and says its accurate it +-.5C, which so far seems to be about right. Have you found any sensors that are accurate?

 

[Ozarks Mountain Brewery]

the ones I settled with are rtd from auber, seem to be more true than the cheap ones off amazon
Class A. +/-0.15 °C at 0.0 °C

 

[Nosybear]

I found one from a science supply store in Houston that is supposed to be accurate to +/- 1°F. Now if I can only get them to process the order....

 

[shizzy]

Are you preheating your cooler? I use an electric tea kettle to boil 1.7L of water that I dump in the cooler 5 minutes before I add the load of mash water. If you don't preheat, you will have some loss.

Are you keeping notes? This will be very important. Referencing what you are brewing as well as outside temps. Online calculators are a wonderful tool, but each cooler will vary. After enough batches, your notes will be able to tell you if you need to increase or decrease by a few degrees.

 

[Smitty27]

Yeah, I always preheat my cooler for about 15min or so. So far my first two resting temperatures haven't been too far off. Its just that final jump to 168 that I can't seem to reach without decocting. But, yes I have been taking notes so I think this next batch will be much closer to hitting the proper resting temperatures. I think I just need to start out with a really thick mash in the beginning to compensate for the large amounts of water towards the end or just pull a decoction during the last bit.

 

[Ozarks Mountain Brewery]

one way to overcome that is have heat under your mash tun, I hear all kinds of posts about ways to keep the mash tun heated to the proper temps, and nobody seems to use a heated mash tun with a pid, not sure why buy my set up has never let me down and I have a 6000 watt element under the mash insert hanging 3 inches above the bottom but going with the norm you can even boil wart to even out the temp, its been done for centuries