Can mash get hotter after turning off the heat source?

[Brownyard]

Anything is possible. I stirred it for a good 5 minutes at least, but that may not be enough for some. It was only 3.5 gallons of water. I'll be doing another test soon. The thermometer always worked great on my standard electric stove top. Maybe once I killed the power on the induction top, the thermometer resorted to proper temp reading, if interference was a factor. I'll try to determine this.

 

[Deadalus]

Anything is possible. I stirred it for a good 5 minutes at least, but that may not be enough for some. It was only 3.5 gallons of water. I'll be doing another test soon. The thermometer always worked great on my standard electric stove top. Maybe once I killed the power on the induction top, the thermometer resorted to proper temp reading, if interference was a factor. I'll try to determine this.

How much grain, about 5 lbs? I'm not really familiar with BIAB brewing specifics but I plugged in a basic BIAB medium body recipe at 3 gallons into Beersmith. The mash calculation came out about the same temperature as your strike temp so I see now where that is closer in temperature to my usual calculations (More water as compared to the grain weight). Something is wildly untrustworthy in the actual measurements, I don't think an answer lies in a potential software input such as not accounting for your equipment or an error in an input field. And that's if you used a software program or brewing calculator. To arrive at 180F, assuming the induction burner was off off, the water would have to have been upwards of 183F to start with. Also, a five gallon pot doesn't weigh much 5 pounds maybe(?) as opposed to 3.5 gallons of water plus about 5 lbs of grain, that's over 30 pounds. It's not boiling but did you notice anything indicating the strike water was that hot (183F)? Getting a little steamy or the pot making creaky noises? What was the specific gravity at the end? I think you would have cooked the **** out of the mash at that temperature.

Is your dial thermometer mounted on the pot? If not, you could try different size pots and see if you get unusual readings based on thermometer distance from the induction burner. Definitely use a small pot as at least one test.

 

[Brownyard]

Well, after doing another test today, I determined that it had to be my error. I tested 4 different thermometers, the 12" dial thermometer I originally used, two new temp probes attached to my ThermoPro TP-08s digital, and a folding instant read digital. All were within 2º of each other throughout the test. Water boils at 211.5º at my elevation, and the two ThermoPro probes registered 211º and 212º, so I reckon that's a .5 degree error. I can live with that, and will use these in the future. I was glad to find there was no detectable interference with any of the thermometers while the induction top was turned on or off. Also, I didn't remove the pot from the cook top at any time. Upon cutting the power at 156º, one of the probes registered a 1º increase in temp, before dropping back. Temp then fell from 156º to 149º over an hour, while cook top was turned off. The pot and lid were covered in 1 layer of Reflectix, with a towel draped over the top.

Possible causes for the original perceived jump from 152º to 180º:

- I found the clip that holds the 12" dial thermometer was moved when the lid was put on, which could have raised the tip out of the wort during one of the readings. It could have been measuring air temp above the wort, or even the side of the pot...

- Most likely though - When I added the grain to the 155º strike water, I stirred it in (really good), resulting in a temp of about 149º. I then turned the cook top up to bring it up to 152º, then I turned it off. There is a real possibility that I failed to stir the wort again after turning the cook top off. If that's the case, I guess the water at the bottom of the pot heated up quite a bit, and when I stirred the wort again at 20 minutes, it brought the temp up to 180º.

Regardless, I'm glad to know I can make the induction burner work. I just need to really pay attention when I add the grains, and stir every time I add heat.

 

[Brownyard]

I think you would have cooked the **** out of the mash at that temperature.

I was afraid of that, but the wort did taste good, and sweet, and OG was 1.059, .003 above target. I only had Windsor yeast, which is apparently a notoriously low attenuator, but after 4 days, gravity had dropped to 1.025. Hopefully it will continue downward over the next couple of weeks. Tastes good though!

 

[IslandLizard]

I guess I need to stir outside of the bag as well?

The mash bag should fill the whole kettle space, wall to wall, or at least very close to filling it. It's counterproductive for mash efficiency having water/wort on the outside of the bag, between the bag and wall, similar to having (too much) deadspace underneath the bag/mash. I can recommend buying a custom made-to-size BIAB bag from @wilserbrewer.

Wrapping a double layer of Reflectix and/or a couple thick, folded-over towels around the kettle during heating, mashing and boiling reduces heat loss. You can't (and shouldn't!) do that on a regular coil or flat top stove, as flammables should be kept well away from the hot glowing coils/elements.
That way your 1800W induction plate will be working much more efficiently.

When mashing place a couple thick, folded-over towels on top of the lid too, for the same purpose.

 

[MajorJC]

- Most likely though - When I added the grain to the 155º strike water, I stirred it in (really good), resulting in a temp of about 149º. I then turned the cook top up to bring it up to 152º, then I turned it off. There is a real possibility that I failed to stir the wort again after turning the cook top off. If that's the case, I guess the water at the bottom of the pot heated up quite a bit, and when I stirred the wort again at 20 minutes, it brought the temp up to 180º.

Yes, this! We were all stumped by the source of the additional heat. The original post did not mention the fact that the burner was turned back on after mashing in. This is definitely where that extra heat came from.