Temperature Drop After Strike Water Is Added

[bleachcola]

Up until now I've been bring my mini mashes up to temperature in my boil pot and then transferring the pot to the oven to maintain 150 to 152 degrees for the mash. I've built a proper mash/lauter tun and will be using it this weekend for an all grain mash. I know every brewhouse is different but I would like some input on how much of a temperature drop you guys experience when adding your strike water. If I want to hit a specific temperature (or close enough to where I can easily adjust with hot/cold water additions) then how much hotter does the strike water need to be? Yes, I can only find out by experimentation, but I'd to find a good starting point for my trials so that I can minimize screw ups before I hit the sweet spot for my unique conditions. If it matters, ambient air temperature will be about 72 degrees and my mash/lauter tun is a converted five gallon round beverage cooler.

[andy77]

I like to use an online calculator.

http://www.tastybrew.com/calculators/infusion.html gets me pretty close. I usually shoot for a degree or two over my mash temp, then quickly stir the heat out. That way I'm not presented with the problem of having too low a mash temp and then not having a easy way to raise it.

[Bugeater]

As you noted the temperature differential will depend on both your setup and your process. In my case, I use a rectangular extra heavily insulated Igloo cooler. I always mash indoors so my mash tun and ambient temperature is pretty close to the same year round. The grain is also stored indoors so the temp is the same as ambient. I add the water to my mash tun using a measuring pitcher and stir the mash really well before putting the lid on. I also preheat the mashtun with 180° water for 15 minutes or so before I dough in.

With this setup, for average size grain bills, I start with 170° water and end up with a mash temperature of 150°. This is with a water/grain ratio of 1.25:1 . If I go for a thinner mash, the differential is a little less. If I go with a larger grain bill, the differential increases.

My pitcher measuring method increases the temperature drop over what you would get if you simply drained (or pumped) water directly from you hot liquor tank to your mash tun. The more you stir, the more the temperature drops.

With my mash tun, once I get the mash temp stabilized, I lose only 1-2° during a 60 minute mash.

As you can see, there are a lot of variables. I would figure on a 15° drop for the first time around. Have a pot of boiling water on the stove and a pitcher of cold water handy to make temperature adjustments if needed. Record the temperature of the mash water and the resulting stabilized mash temperature before making adjustments with the hot or cold water. You have a good 5-10 minutes to make the temp adjustments so you don't need to get in a big hurry. Once you know the temperature drop it is easy to adjust the mash water temperature for the next time you brew. If you were 5° low you simply raise the mash water temperature by that much. Also once you know the differential you can easily adjust the mash water temp for different desired mash temps the same way.

This should either confuse you completely or clear things up. Either way, relax, have a beer, and go ahead and brew. Just take good notes.

Wayne

[bleachcola]

As always, excellent advice within minutes. Appreciate the help fellas.

[DannyW]

Interesting, Bug. I have the same sort of mash tun, never preheat, and strike about 20F above desired mash temp (i.e. 172F for 152F mash). Hits it every time. I don't even keep ice or boiling water around any more. Maybe the well insulated plastic walls of the cooler absorb so little heat that preheating doesn't matter?

[Brandt]

I had a strange session this week. My mash proceedure is exactly like Bugeater's. It has been consistent for years. But this time, I did everything by rote, but my water in the tun was off by 12 degrees. Luckily I caught it before I added the grain, and I have a couple of heatsticks. I was able to heat the water directly in my cooler before I added the grain. On the second batch, I decided not to wash out the mash tun after the first, because I had managed to dump out almost all the spent grain. I figured the tun would hold the heat well, and I could skip the preheat. Again, I added the hot liquor and the temp dropped about 10 degrees below what I calculated. Additionally, I lost 6 degrees over an hour or so which is an anomaly in my setup.

Still scratching my head over this, but I set the thermal mass value of the mash tun in Promash to .4 and the numbers look about right. Next time I'm going to heat the liquor more to compensate, but I hate that I had the process dialed in for so long and now it's gone wonky.

[brew_chica]

We use a gatorade cooler for our mash that sits out in our garage all the time so its always pretty cool when we go to mash but never the same temp - what we've taken to doing to compensate is to calculate our strike water temp and then add 5-6 degrees. We pour it in the cooler - shake it around and then re-measure the water to see if it dropped to strike temp and then add cool water as necessary before adding our grain. It's worked pretty well for hitting our mash temp pretty consistently. Since its your first batch I'd add 10 degrees and then adjust from there - we've learned the hard way its a lot harder to adjust the temp after the grain is in.

Brew on!

~brew_chica~

[Quin]

If you are math inclined, Palmer's book has the equations for calculating the temps

http://www.howtobrew.com/section3/chapter16-3.html