Mash tun lost 7 degrees in an hour. Awful?

Does it ruin the mash to add more water to raise the temp?

My previous post stated it held heat like a champ. I may have lied.

Thanks,

 

It will change things slightly by adding more hot water. Instead take some blankets etc. and wrap them around your mast tun to insulate. Pre-heat it also so the heat doesn't go into the walls of the mash tun.

7 degrees is a lot but not a disaster. Most of the conversion will have taken place before the temperature got too low.

 

Ya know what? I didn't preheat it. That must have been the issue. Thanks for the help!!

 

Are you referring to the temperature drop between post-mash-in and the end of the mash? If so, 7 degrees is a lot. I use an an orange Igloo cooler, and I've never had the mash drop more than 1 degree. If you're talking about temperature of water transferred to the mash tun vs. mash end temperature, 7 degrees is nothing.

IMO, the pre-heating trick only really helps if you're going in blind on new equipment and want to improve your chances of landing at a target mash temperature. If you keep some records on temperatures (of water at time of transfer, inside mash tun after 10 minutes pre-heat, 10-15 minutes into mash), mash thickness, etc. you can quickly get to a point where you will know how high to heat up the water before transferring to the MT such that all cooling effects are taken into account and you land at your target once the grains are added. I'm never more than a degree off now, which is more than close enough.

 

It was the mash in temp drop...I was just doing a test drive yesterday with hot water...no grain. I'll have to play around. I use an orange Home Depot cooler modified to a mash tun.

 

If that was the drop of your strike water after adding it to the MT it seems right on target....how did the temp hold from that point forward?

 

As a side question, would the amount of head space, I have a 15 gallon cooler but typically do 5 gallon batches. My temp drop is about 5

 

I'm a big fan of pre-heating the mash tun. It's easy to add some 150F water and let it sit for as few minutes - especially in winter. Your always starting with the mash tun at about the same temperature, as opposed to having to guess.

I think head space will definitely make a difference.

 

The hot water went into the mash tun at 169...an hour later it was down to 162.

 

I have a 10 gallon mash tun and put in about 6 gallons of water for the test.

 

If you don't preheat you're screwed. You'll lose 5 or more degrees pretty easily. It happened to me once on my second AG brew with my orange 10 gallon cooler. Now, I heat up my strike water, through it into the tun at about 180, put the lid on, and wait 15 minutes or so. I then take the lid off stir and get the temp down to strike temp and add my grains. After about 4-5 brews I nail my mash temp within 2-3 minutes of breaking up the dough balls and its steady for the entire hour.

 

Like I said, I pre-heat my mash tun.

I generally lose 2F or so over a 1 hour mash. During the winter, maybe 3F-4F. My mash tuns are usually filled to the rim.

 

This is most likely the issue. I mash in an el cheapo rectangle cooler and only drop about 1 to 1.5 degrees in an hour.

I always run the hottest tap water I can into it (about 2 gallons) to preheat. I leave that until my strike water in the kettle is about 5 degrees hotter than I really want. Then I dump the preheat water, transfer the mash water to the cooler MLT and stir until it drops to my desires strike temp. Dough in and stir vigorously for about 5-10 mins and the mash is on. I stir a couple times during the mash with another very vigorous one and settle right before vorlauf.

 

Try puttin foil over the grain bed too

 

I used to add hot water to my mash tun (converted Home Depot cooler) and then dump it out to preheat it. Then I read a good suggestion on this forum which is to add my mash water (with all the brewing minerals added per Brun Water) at a temperature about 5F higher than my strike water temperature. Let that cool down to your strike water temperature and then put in your grains. I hit my desired mash temperature pretty close and I lose about 2-3F in an hour with the cooler. Not too bad.

 

Running a test of your mash tun with just water is not a valid test. A mash is a thermally different animal than water and will hold heat much better.

A water only test is a waste of time IMO, get busy mashing grain not water lol.

 

For what it's worth, I was losing some temp over 60 min from my mash in a rectangle cooler, until I figured this out: The cooler, which is built to keep heat OUT (not in), was radiating heat right out the top through the hollow lid. I drilled some small holes in the lid, just big enough to fit the nozzle tube of spray foam insulation through, and filled the lid with that stuff. Don't lose temp no more.

 

if it's a cooler - I don't believe you should lose more than a couple of degrees over an hour unless there is something fundamentally wrong with it - which is likely soluble by using a blanket or something

I use 2.5L per 1KG of strike at 77C which drops my room temp grain down to 68C

I need to give it a really good stir not just to get the dough balls out but also to even the temp

I think pre-heating is not worth the trouble as you just need to raise the strike a bit higher to have same effect - for me anyway

also, once you have confidence in the temp drop it's best to not open it on future brews but check it at end of mash

 

This feels right since with my cooler, the sides are cool and the top is warm.

I will investigate, since I assumed the top would have been insulated as well.

 

I've never had a plastic cooler with an insulated lid.
Be careful about filling them with foam. If you use the wrong kind it'll never cure...

Cheers!

 

Are you using any brewing software? I brewed two separate 10 gal batches today and was right on the money both times. The temp of the tun and grains will give you needed strike temp (brewsmith). I have a too large rectangular mash tun and the software really helps. I also just finished building a RIMS system which was needed since I did not have any heat source. This was the fourth time on the RIMS and it really upped the game of my brew house. The RIMS is an expensive option (come close then heat) but the software should help.

 

I have a 5 gallon round cooler and use about 3 gallons when I brew...So I pre-heat and also have cut a piece of cardboard the diameter of the cooler which I cover w/Al foil. This is pushed down to the level of the water. This tends to give me a 3 gallon cooler. Got the idea HERE some years ago.