New Mash Tun Temp Control

Just did my first brew with the new MT...10 gallon MegaPot with a bazooka tube. I had major problems keeping the mash temp stable with this new tun.

Heated strike water to 163 to mash in and hopefully seal the tun at 151. Once I added the strike water and stirred, the Brewometer read about 146-148. Decided to add heat from the burner. Stirred and finally sealed at 151. 15 minutes later the Brewometer read 180!!! Kept the lid off and stirred for a while. Temp only got down to about 158.

Sparge was the same type of disaster. Heated water to about 180 but when all was over, temp read about 142. I verified with another thermometer. When I used to use a cooler for mashing things were always spot on. Need major help with how to mash and stabilize temp with this new tun. Thanks in advance!!!!

Are you using no sort of automation system whatsoever?

Basically you need to apply very careful and precise amounts of heat based upon the temperature inside the tun. That's why people use temperature controllers, thermowells and solenoid valves... otherwise you have no idea what is going on. Otherwise how do you know how much heat is actually going in there? You can't.

In my experience strike water calculations are extremely accurate. Sometimes the temp dips below what you want and then a minute or two later catches back up as the mixture finds its balance. It would be helpful to get some sort of insulation on the kettle to limit how much you have to apply heat. And remember it can take time for a temp probe to catch up to the actual temp so by the time you turn off the heat because the probe reads the desired temp it is already going to be shooting up well beyond what you intended.

The one variable I have found that kills the strike temp is the temp of the grain prior to adding to water. Otherwise its pretty dead on.

badmajon said:

Are you using no sort of automation system whatsoever?

Basically you need to apply very careful and precise amounts of heat based upon the temperature inside the tun. That's why people use temperature controllers, thermowells and solenoid valves... otherwise you have no idea what is going on. Otherwise how do you know how much heat is actually going in there? You can't.

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Thanks for the info. I never had to do any of these things when mashing in the cooler. Things were always very accurate without automation, pumps, etc.
Just trying to figure out how I need to go about my mash with this new my. Thanks.

Bensiff said:

In my experience strike water calculations are extremely accurate. Sometimes the temp dips below what you want and then a minute or two later catches back up as the mixture finds its balance. It would be helpful to get some sort of insulation on the kettle to limit how much you have to apply heat. And remember it can take time for a temp probe to catch up to the actual temp so by the time you turn off the heat because the probe reads the desired temp it is already going to be shooting up well beyond what you intended.

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Excellent advice! Insulation jacket is a great idea. Do you think it was an issue that my temp probe was only about an inch under the top of the grain bed? I was thinking that if the probe was in the middle of the bed it could have been more stable.

The difference is now he's not using using a cooler and using strike water calculations, but he's using some kind of direct fired mash tun... I can't imagine doing it w/o the automation equipment b/c there is no way to control the heat or know what is going on in there.

I say build a HERMS system.

I use a cooler, but would really like to be able to direct fire like your system. I would recommend adding heat, as Bensiff advises, a little shot at a time. 1 minute of heat then stir for a few minutes until the heat has dispersed. If it takes a few minutes to get up to temp, it will do no harm. It's easier to add heat than take it away.

As for insulation, build a hexagonal box with 2" rigid foam. Hold the pieces together with duct tape. You can hinge one edge with tape and use velcro on the other side. Then make a lid. That would be more well insulated than a Igloo cooler by far, because of the lid.

Thanks Northcalais40. Regarding the lid, do you mean putting an insulated lid over TOP of the MegaPot lid that is part of the fabricated hexagonal box? Assuming so, just making sure I'm clear.

Excellent advice from everyone. Thanks.

I'll try to respond to multiple issues. First, you are direct firing into mash with nothing separating the grain from the bottom of the pot, this is a recipe for scorched grains and ruined beer. The best solution here is a false bottom so only the wort touches the heated surface. Next, you need a way to keep the heat dispersed. You can be as simple as constantly stirring, you can get a low rpm gear drive and build a mash stirrer, or go somewhere in the middle and hook it up to a pump and constantly circulate the wort through the mash (added benefit is it is already vorlaufed when you are ready to sparge). If you don't do something like that then it doesn't matter where the temp probe is as you will always have hot and cold spots so you will have no consistency. If you use a pump to recirculate one of the best places to locate the probe would be on the outlet spigot (attach a "T" to the spigot with a barb or quick disconnect on the downspout for the hose and on the remaining opening of the "T" add a 1/2" x 1/4" plug to screw the thermowell into.).

As badmajon said, some level of automation will really make life easier. As a solenoid valve will automatically shut off the propane the second the temp controller activates. You would also say in the name of conserving energy and keeping your mash temp more stable that insulating the pot as much as possible to include a lid is highly recommended...in the meantime do use the lid.