New Mash Tun Efficiency Dropped

Hello All,

I have been all-grain brewing for 8 months now and decided to upgrade my mash tun from a 5 gallon water cooler to a 10 gallon water cooler and I am having a couple of problems.

1.  With the new cooler, I am getting brewhouse efficiency around 50%, with the 5 gallon tun I was closer to 68%.  I have not changed the grind of my grains.

2.  Using beersmith, I created a new equipment profile for the new tun, but I am finding that I was undershooting the mash temperature by ~4 degrees F.  With the old tun I was hitting mash temperature perfectly.

I have brewed with this new setup 3 times now.  After the first time, I started heating up my strike water a few degrees warmer so that I would hit the proper mash temperature.  I am now overshooting by 4 degrees (btw target 150F for the mash).

I think I can dial in the mash temperature, but the efficiency has be concerned.  A small drop in efficiency would seem reasonable (a few percent) but 18% seems like I need to fix something.

Any suggestions?

Thanks

Some questions for you...

Are you losing more heat during the mash with the new mash tun vs. the old mash tun?
Is your grain bed deeper now than it was before?  Shallower?  The same?

Thanks for the response.  As far as heat loss.  I am noticing a little heat loss compared to the old tun, but only about 1.5 degrees over 1 hour of mashing.

The grain bed is shallower due to the larger diameter tun.  The old tun was ~12in in diameter, the new tun is ~18in in diameter.

-Steve

What is your false bottom/drainage braid/piping look like?  If it is a single braid running through the center of the mash tun, that combined with a shallower mash could be the issue with the efficiency drop.  I tested mine using spent grain and food dye and ended up with a circular braid to give me the best drainage configuration (round beverage type cooler).

Oginme asks some really pertinent questions. I use a 50 litre (approx 12 gallon) rectangular esky with a home-made copper manifold (as per the design in one of the appendices in John Palmer's book). So for standard 6 gallon batches, I had problems with the grain bed being too shallow, and for 12 gallon batches or higher gravity beers, stuck sparges. Once I almost doubled the number of saw cuts in the manifold, most of the problems went away.

However, for quite high gravity brews (say, 1.070 or above), I discovered malt conditioning is the solution (there's a link to this topic on Braukaiser.com -- many people don't like the idea, but if I keep the amount of water below 200 mls per 10 kg grain, it has been an absolute saviour for me and my brewing).

Great insightful questioning, Oginme. I suspect you've nailed the problem.

Cheers all.

Thanks, Anitphile. 

I mostly do 10 liter BIAB brewing, but a couple of years ago I decided to move some recipes to a 20 liter traditional mash tun set up.  I also wanted to use the system for 10 liter batches outside (I normally do the 10 liter batches inside) for when the weather gets too warm for inside brewing.  So after investing in a 5-gal beverage cooler and connecting a single braid running down the middle, I decided to estimate what kind of efficiency loss I would get (it's the process control engineering background poking its ugly head up).

So I took the spent grains from an average batch and poured it into a large bowl (I squeeze the bag well, so there was not much free water), mixed in blue food coloring and put it back into the bag to see how well the blue drained out.  Tested it first in my 20 liter pot I use for BIAB and digging through the bag afterwards, noted that most of the dye had leached out with maybe a slightly bit more color in the middle of the grain bag.

I repeated the test in my new mash tun after adding more dye.  This time after digging down, I noted a deep blue in the corners away from center braid. 

I changed braids for a new one, replaced the barb with a tee and put a barb on both sides.  This gave me a singular round braid sitting about 3/4" from the inner wall of the mash tun.  Repeated the test on the next weekend and noted just a slight bit more blue in the very center than everywhere else in the mash tun. 

It is a pretty simple test, but gave me a lot of insight into the drainage from the mash tun vs biab. 

All,

Thanks for the feedback.  I had transferred my circular braid from the 5Gal tun to the  10Gal tun but it looks quite small in comparison to when it was in the 5Gal (the furthest part of the loop hits just past the center of the tun).  I think a trip to Home Depot is in order to get a longer braid so that the loop can say 3/4" all the way around the larger tun. I'll see if that gives my efficiency a little boost.

-Steven