Efficiency Problems - Converted 50L Keg Mash Tun

We have recently increased our brewing system capacity.

Our mash tun consists of the following:

• 50L Stainless Steel keg with a 2kW electric element - not insulated
• Copper pipe manifold
• Connected to a normal ball valve
• Stainless Steel lid

We mash at a ratio of 3kg/L.

Since moving to this system our mash efficiency is really poor. Probably in the order of 45-55%

As far as I can gather there are a few basic causes for efficiency problems:

• Incorrect grain milling
• Temperature issues
• Sparging issues

We buy grain already milled from one of our regional brewers, so milling is not the likely issue.

Temperature issues are possible. It is winter here at the moment. The ambient temperature when brewing is in the order of 15-20C.
Since most of you guys in the northern hemisphere have to deal with much colder weather the following questions:

• Will the outside of the mash cool that much quicker than the core and affect the efficiency?
• To counter this effect what would you recommend: Insulating the mash tun; stir the mash periodically and switching on the element; or a combination of the two?

We have not quite cracked the sparging. Previously we added sparge water manually, but now we use a pump. I suspect the rate of adding water is too high.
What flow rate would you recommend for sparging; and at what temperature is your sparge water normally?

All help will be appreciated

Schalk79 said:

Our mash tun consists of the following:

• 50L Stainless Steel keg with a 2kW electric element - not insulated
• Copper pipe manifold
• Connected to a normal ball valve
• Stainless Steel lid

We mash at a ratio of 3kg/L.

Click to expand...

Is the element "direct fire" or in a RIMS tube? I would suggest a RIMS tube build to even out the temps. Insulate that tun. Insulate the lid.
Look here for examples

Schalk79 said:

As far as I can gather there are a few basic causes for efficiency problems:

• Incorrect grain milling
• Temperature issues
• Sparging issues

Click to expand...

Schalk79 said:

We buy grain already milled from one of our regional brewers, so milling is not the likely issue.

Click to expand...

Buy a mill and get some feeler guages from a hardware store and set it to the correct gap for the grain you are milling. Yes, different grains mill better at different gap sizes.

Schalk79 said:

Temperature issues are possible. It is winter here at the moment. The ambient temperature when brewing is in the order of 15-20C.
Since most of you guys in the northern hemisphere have to deal with much colder weather the following questions:

• Will the outside of the mash cool that much quicker than the core and affect the efficiency?
• To counter this effect what would you recommend: Insulating the mash tun; stir the mash periodically and switching on the element; or a combination of the two?

Click to expand...

Yes, the outside cools quicker. Do you remember your mom telling you to eat soup from the outside of the bowl when it was too hot? Go to Here to look at systems to help control temps.

Schalk79 said:

We have not quite cracked the sparging. Previously we added sparge water manually, but now we use a pump. I suspect the rate of adding water is too high.
What flow rate would you recommend for sparging; and at what temperature is your sparge water normally?

All help will be appreciated

Click to expand...

Batch sparge with the RIMS system and you will have awesome extraction of sugars. Keeps clarity also.

Thanks for the feedback and the links...

Insulation for the mash-tun is most definitely the next thing to be done.

Our mill is in the post and should be here any day. Guess we'll have the crushed grain sorted then.

The electric element is direct fired. I'll test it with a thermostat & more stirring while we modify the mash tun to a RIMS system using our HLT as a heat source.
I think we can also make our mash a little thinner. It should also help by keeping the mash more liquid and able to move around - the heat should even out with the help of some stirring

Yesterday we brewed a Cascadian Dark Ale (Black IPA) and it seems as if we have solved our efficiency problems.

On closer inspection the milled malt we bought from a local brewery was poorly milled. More than half the grains were still intact. (Now I know why they add so much glucose syrup to their crappy beers).
Luckily our new Crankandstein mill arrived on Friday.... After a quick hopper build we were in business!! It worked like a charm and we had properly milled grain.

We insulated the mash tun sides temporarily (still waiting for proper insulation to arrive) and managed to keep the mash within a 3degree band throughout the hour of mashing.

Sparging was done in batches and we built a new sparge arm which seem to work quite well.

We hit the target gravity bang-on... Think we are back to a 70+ % efficiency !!

Awesome!!!