Pre-heating a mash tun..

[tre9er]

I've recently converted to the "heat way over strike temp and wait, then stir down to mash temp" method, too. Much easier than adding water because you're too low.

 

[thetragichero]

here's how i do it (and get 75+ efficiency):
heat 2-3 gallons of water until boiling or near-boiling (usually do this as soon as i get home from work so i'm doing other things while it's heating: gathering equipment from the spare bedroom that's ended up with tons of brew equipment in it, finding something good on tv to listen to, etc) it usually ends up boiling so i remove it from the burner and let it sit a bit while i wash the mash tun and make sure the valve on it isn't leaking
fill the mash tun (5g rubbermaid beverage cooler that will soon be replaced with a 10g), close the lid and throw a couple towels on top of it
bring water to strike temp, empty mash tun right before mash in

 

[goosegrease]

+1 on the 10 degree hotter strike water to pre heat mlt. I drilled holes in my rubbermaid lid and filled them with foam, let that dry, then filled the surface holes wit a dab of caulk. It seems to retain heat very well with no blankets or towels.

 

[Stauffbier]

What were your findings? I AGAIN got low efficiency on my oatbier last weekend. In the 60's. I mashed around 1.25 and did a mashout, vorlauf, drain, sparge, vorlauf, drain...but I noticed my absorption was way higher, made my volume lower. I think the deadspace in my tun affected volume, too. When I realized volume was low I should have added more sparge water and done another batch sparge. As it was, I added water to the boil which had 0 sugars in it. Thinking that's the reason.

I mashed in at 1.34 qts/lb like I mentioned and I got 79% efficiency. I can't say that it helped anything to go thin, since I've gotten 79% efficiency on batches as thick as 1.15 qts/lb before. I also lost more to grain absorption this time for some reason. Usually my predictions are right on, so I'm not sure what happened with this batch. I have a friend who likes to mash real thick (1qt/lb) on his dark beers, and he always makes exceptional beer. I might try a real thick mash next time to see what happens...

 

[tre9er]

it's interesting because other tests would suggest there is efficiency to be gained by mashing thin.

 

[Stauffbier]

it's interesting because other tests would suggest there is efficiency to be gained by mashing thin.

I agree. I've read it on many occassions, but I've also heard people say the opposite. There are just too many variables when it comes to efficiency from one brewer to the next. I like to experiment with different things to see if I can raise my efficiency, but I think more importantly it's better to achieve consistancy. I'm pretty happy with my consistant 75-79% range, so I don't feel overly compelled to improve it. That doesn't mean I won't keep experimenting, but if I never do any better I'm fine with that...

 

[Mindhop]

I am surprised that this has not been mentioned yet. I stopped preheating my mashtun. I just mash in around 168ish in a cold cooler. I leave my last gallon out until my temp reaches 152ish. If it is to high I add cold water. I will lose a degree in an hour. I usually get 80% efficiency. I'm not saying my way is better but just different.

Cheers

 

[Stauffbier]

I am surprised that this has not been mentioned yet. I stopped preheating my mashtun. I just mash in around 168ish in a cold cooler. I leave my last gallon out until my temp reaches 152ish. If it is to high I add cold water. I will lose a degree in an hour. I usually get 80% efficiency. I'm not saying my way is better but just different.

Cheers

You must be the exception to the rule then. If I did that my mash would end up in the mid to low 140's.. My cooler absorbs way too much heat to do that.

 

[ChemE]

I spent some time when I first set up my MLT playing around with my equipment settings in BeerSmith. Specifically for me I added the weight of the MLT and had to change the heat capacity from the default 0.3 cal/g°C to 0.525 cal/g°C (this based on initial observations of my first few strikes and the resulting temperature of the mash). Once I fixed these two things BeerSmith nails my mash temp within 1°F every time. To me preheating is just one extra step on brew day and really is only a band aid applied to the wound of imprecision. Another trick that I didn't see mentioned was placing aluminum foil under the lid. Not only does it stop convection as the saran wrap mentioned but it also stops virtually all the radiation losses which is VERY significant.

Regarding thick/thin mashing and efficiency a huge benefit to a thick mash is you have much more sparge water to lauter with. My finest beer is an oatmeal stout that I nailed 92% efficiency on and sparged down to 1.003 during the lauter. pH never rises because I carefully work my salt profile and mash salts so I do not fear tannin extraction.