Should a Rubbermade MLT be preheated

[bigbellybrewery]

I recently converted from a 5 gallon Rubbermade to a 10 gallon used as a MLT. I always preheated my 5 gallon with 180-200 degree water and always hit my target temp. My 1st 10 gallon AG with my new 10 gallon MLT immediately warped when I preheated with 180 degree water. Cooler is still intact but I don't want to cause further damage.

Rubbermade users: Preheat or not. If not, are you hitting your target temps by using Beersmith's or equivalent calculation?

 

[Brewsmith]

Preheat, but use slightly colder water. I use 160-165 degree water so that everything settles to about mash temp. I have one small spot that warped in mine once, but that's it.

 

[nathan]

You can take a sauce pot, heat it on the burner, and toss in a quart or so when it's 160, then another quart when it hits 170, and keep going like that until your cooler gets to temp (or you run out of quarts in the saucepan). The hotter water hitting the cooler water warms it more gently.

 

[bradsul]

I just use hot tap water and the promash calculations are always dead on for me.

 

[blacklab]

I just use hot tap water and the promash calculations are always dead on for me.

+1 with BeerTools, too

 

[Brewmando]

My 1st 10 gallon AG with my new 10 gallon MLT immediately warped when I preheated with 180 degree water. Cooler is still intact but I don't want to cause further damage.

This happened to one of my brew buddies which in turn detached the false bottom from the pick-up the first time and once that was corrected the warping allowed grain to get under the false bottom plugging the pick-up. This seems to be an issue with the Rubbermade coolers. This does not seem to be the case with the Gott coolers. Spend a few more $'s on the better Gott cooler and the problem is solved!