# Thermal mass of 3 gal mash tun? **URL:** \ **Category:** Systems, Gear, & DIY\ **Created:** [October 20, 2010, 5:03pm UTC](https://forum.homebrewersassociation.org/t/thermal-mass-of-3-gal-mash-tun/3581 "2010-10-20T17:03:23Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![ipaguy](https://avatars.discourse-cdn.com/v4/letter/i/977dab/32.png) [@ipaguy](https://forum.homebrewersassociation.org/u/ipaguy)\ **Post date:** [October 20, 2010, 5:03pm UTC](https://forum.homebrewersassociation.org/t/thermal-mass-of-3-gal-mash-tun/3581/1 "2010-10-20T17:03:23Z")
I just received a 3 gal. Rubbermaid mash tun kit from Midwest Supplies.  I plan on trying it out on a partial mash recipe in the next couple of weeks.  I’m using pro-mash, and am interested in using the strike temp calculator.  If anyone uses a similar setup, and has a good handle on what to plug in for thermal mass, I would appreciate the info.  If not, I guess I can always low-ball my estimate, and raise the temp by adding extra 200F water until I get it right. ---
**Author:** ![hokerer](https://sea1.discourse-cdn.com/brewersassociation/user_avatar/forum.homebrewersassociation.org/hokerer/32/266_2.png) [@hokerer](https://forum.homebrewersassociation.org/u/hokerer)\ **Post date:** [October 20, 2010, 6:27pm UTC](https://forum.homebrewersassociation.org/t/thermal-mass-of-3-gal-mash-tun/3581/2 "2010-10-20T18:27:33Z")
> [@ipaguy](#): > > I just received a 3 gal. Rubbermaid mash tun kit from Midwest Supplies.  I plan on trying it out on a partial mash recipe in the next couple of weeks.  I’m using pro-mash, and am interested in using the strike temp calculator.  If anyone uses a similar setup, and has a good handle on what to plug in for thermal mass, I would appreciate the info.  If not, I guess I can always low-ball my estimate, and raise the temp by adding extra 200F water until I get it right. Another way to do it is, say ProMash says your strike should be 165 degrees.  Go ahead and heat your strike to 170-175, dump it in the cooler, and then wait until it drops to 165, and then mash in.  No need to try and figure thermal mass or anything like that. ---
**Author:** ![ipaguy](https://avatars.discourse-cdn.com/v4/letter/i/977dab/32.png) [@ipaguy](https://forum.homebrewersassociation.org/u/ipaguy)\ **Post date:** [October 20, 2010, 9:58pm UTC](https://forum.homebrewersassociation.org/t/thermal-mass-of-3-gal-mash-tun/3581/3 "2010-10-20T21:58:53Z")
Thanks for the suggestion.  I just realized that I should be able to calibrate the thermal mass pretty well without any grain in the thing.  I figure that I can just set ‘total grain’ to 0.01 lbs., dump in a couple gallons of water at around 170F, and check the resulting temp.  Then adjust the thermal mass value to get a matching result.  Before making a batch for real though,  I’ll definitely take your suggestion and add water to the tun first and do a double check before adding grain. ---
**Author:** ![tubercle](https://sea1.discourse-cdn.com/brewersassociation/user_avatar/forum.homebrewersassociation.org/tubercle/32/6256_2.png) [@tubercle](https://forum.homebrewersassociation.org/u/tubercle)\ **Post date:** [October 20, 2010, 10:26pm UTC](https://forum.homebrewersassociation.org/t/thermal-mass-of-3-gal-mash-tun/3581/4 "2010-10-20T22:26:45Z")
> [@hokerer](#): > > > [@ipaguy](#): > > > > I just received a 3 gal. Rubbermaid mash tun kit from Midwest Supplies.  I plan on trying it out on a partial mash recipe in the next couple of weeks.  I’m using pro-mash, and am interested in using the strike temp calculator.  If anyone uses a similar setup, and has a good handle on what to plug in for thermal mass, I would appreciate the info.  If not, I guess I can always low-ball my estimate, and raise the temp by adding extra 200F water until I get it right. > > Another way to do it is, say ProMash says your strike should be 165 degrees.  Go ahead and heat your strike to 170-175, dump it in the cooler, and then wait until it drops to 165, and then mash in.  No need to try and figure thermal mass or anything like that. Do what hokerer said. Its the easy way. Don’t pay attention to the water/grain first argument because it doesn’t matter. You will eventually learn what temp to dump in the grain. For my set up and when mashing my 7% lawnmower beer for example, I just pour in 170f water, stir until I get 14f above my strike temp and give it the grain. I’m within 2f every time. YMMV ---
**Author:** ![guitarbrew](https://sea1.discourse-cdn.com/brewersassociation/user_avatar/forum.homebrewersassociation.org/guitarbrew/32/11268_2.png) [@guitarbrew](https://forum.homebrewersassociation.org/u/guitarbrew)\ **Post date:** [October 21, 2010, 4:07pm UTC](https://forum.homebrewersassociation.org/t/thermal-mass-of-3-gal-mash-tun/3581/5 "2010-10-21T16:07:31Z")
You could do what I do.  Heat the water past what you expect to need.  Keep a gallon or so of cool water on hand to quickly stir in to reach mash temp.  I do worry that this method destroys the betaamalyse (sorry if this is wrong) enzymes that are able to chomp longer chains making a thinner bodied beer.  However, I have produced some very good beers with this method.  One, a saisson, had an OG of 1.080+ and a FG of 1.008.  All other beers have attenuated as expected based on my target mash temp, that I always hit. I do it this way because it is much easier than being too cold and having to try raising the temperature. ---
**Author:** ![kit\_b](https://sea1.discourse-cdn.com/brewersassociation/user_avatar/forum.homebrewersassociation.org/kit_b/32/13535_2.png) [@kit\_b](https://forum.homebrewersassociation.org/u/kit_b)\ **Post date:** [October 21, 2010, 7:24pm UTC](https://forum.homebrewersassociation.org/t/thermal-mass-of-3-gal-mash-tun/3581/6 "2010-10-21T19:24:38Z")
In the future, when you find the need for a larger tun, skip those water cooler styles & go to a tun like Denny’s. (Big, blue rectangular cooler) I have a pair of 10 gallon water cooler tuns & wish I had gone with rectangular ones, instead. ---
**Author:** ![ipaguy](https://avatars.discourse-cdn.com/v4/letter/i/977dab/32.png) [@ipaguy](https://forum.homebrewersassociation.org/u/ipaguy)\ **Post date:** [October 22, 2010, 2:46pm UTC](https://forum.homebrewersassociation.org/t/thermal-mass-of-3-gal-mash-tun/3581/7 "2010-10-22T14:46:09Z")
> [@](#): > > In the future, when you find the need for a larger tun, skip those water cooler styles & go to a tun like Denny’s. > (Big, blue rectangular cooler) > I have a pair of 10 gallon water cooler tuns & wish I had gone with rectangular ones, instead. Thanks for the good advice.  I may get a tun capable of handling all-grain in the future.  I figured that it was still not a waste of money to have a 3 gal tun for the occasional partial mash recipe.  My understanding is that you don’t want too large an area, or too thin a grain bed, to get good filtration of the wort. I know that I’m a little OCD about the ‘thermal mass’ issue.  Probably because I’m a programmer and figure that software that I actually paid for should be configured and used properly. ---
**Author:** ![ipaguy](https://avatars.discourse-cdn.com/v4/letter/i/977dab/32.png) [@ipaguy](https://forum.homebrewersassociation.org/u/ipaguy)\ **Post date:** [October 29, 2010, 3:36pm UTC](https://forum.homebrewersassociation.org/t/thermal-mass-of-3-gal-mash-tun/3581/8 "2010-10-29T15:36:19Z")
Did my calibration on the 3gal tun and got a value of 0.225 for ProMash thermal mass.  Should be brewing in the next couple days.  Will probably upgrade to a larger tun eventually.  Cool looking toy I have my eyes on is a Blichmann AutoSparge.