Help with Problem - Efficiency Issue

I am back to AG again and had a real problem this weekend.

Set up is SS braid in a 70+ quarter Coleman Extreme - no problems with the drain off. This is first time using the braid and the cooler.

Mashed 7 lbs at 151 degrees and left for 2 hours - when I came back it was in the 140 range. I think this is the problem - the Coleman did not hold the heat despite being pre-heated since there is so much space. I wonder if I really got good conversion? Did not use Iodine test

After 2 hour when I came back, I tried a decoction to get it up but only got to about 155 degrees.

Added sparge water at 180 degrees, let it sit for a couple of minutes and let it flow wide open per Denny Brew batch sparging comments

I added the other half of the sparge water and did the same

Made sure to collect 5 gallons.

Checked thermometer and hydrometer - they are calibrated.

Got about 18 points per gallon and hoped to get 26 points per gallon.

Comments and suggestions are really appreciated. Discouraging day

I have the same cooler. My first time using it, I noticed that even after pouring in ~4 gallons of 140 degree water to pre-heat, it still wasn't warm enough. When I poured in my mash water, the temp was lower than I anticipated, so I had to head up another ~3g to try again. So ensure you're properly pre-heating the cooler; I use about 160 degree water now.

I also found that I could see steam coming from the little indentation for the handle on the lid (to lift it up, opposite of the hinges). So I now throw a large towel over the entire top to ensure a seal.

Finally, are you sure a 2 hour mash is necessary? I'm not sure what exactly you benefit from that, but the norm I have heard is 60-90 minutes. Hopefully someone with a bit more experience can chime in on that.

Good luck!

What temp did you pre-heat with? I did this by accident my first time but I found it worked well. What I did was preheat with my strike water to a temp about 15 degrees higher than my mash temp. Then once the temperature in the cooler came down to about 5 degrees higher than my mash temp, I added the grain. I still lost about 5 degrees over an hour but most of the conversion should have been completed by the time the temperature dropped. I only got about 65% brewhouse efficiency but that's what I planned on. Plus, I think I can up that a bit with more sparge water. I shorted myself a bit.

A few things jump out at me.

1) Why the two hour mash?

2) 7# of grain in a 70qt extreme is not much at all. Not saying it isn't possible but with such a shallow grain bed you might consider putting a piece of insulation on top of the mash to retain heat.

3) Use 180 degree water to preheat your MLT. It makes a difference.

Too much head space, all your heat escapes to the air gap in your cooler, 7 #'s of grain is too small for such a large cooler to be efficiant. Sorry to be the bearer of bad news, but you need to do 12 #'s or more in that set up. Your current cooler is not out of the picture all together, use it for your HLT!

I have used this cooler with 10 lb batches and had no issues with retaining heat. I have maybe lost 1 degree/hr. I really believe that throwing a heavy towel over the lid to drape down and cover the seam between the lid and the cooler walls makes all the difference in retaining heat. Otherwise, you can literally see the steam rising from the handle area.

Did you stir the sparge water after adding it? That can make a very big difference.

-a.

The reason for the 2 hour mash is that I am playing around with an idea whereby I start the mash, do dinner with family, put kids to bed, and then finish my brew day. It can't hurt, but efficiency was really bad

On the cooler, I purchased a smaller one today. The surface space was likely too big. Someone mentioned insulating the mash. What about putting aluminum foil over the top of the mash to help retain heat? Any issues with this - I would guess the foil has an inert reaction, but I was an economic major, not a science guy

thanks for thoughts.

Don't pass on the important question regarding stirring the mash after each sparge infusion. Phlyanpan has it right. Get the strike water up to like 175F, close the cooler for 5 minutes and then wait for it to hit about 168 before you dough in.

The other thing is that you said you collected 5 gallons. Was this for a 4 gallon finished batch?