Changed MLTs and missed my numbers?

nicadrick · 12-21-2009, 02:01 PM

Hey all,

I have been very successful using my 5 round igloo cooler MLT with SS braid. I have hit my start gravity each batch.

I decided to brew a scaled version of one of my past recipes to make a 10 gal batch. I converted a coleman extreme rectangular cooler per the wiki and equipped it with a manifold per the wiki?

I followed the same batch sparge steps as I do with my 5 gal round MLT.

This go round, I missed my start gravity by almost 10 points?

Any ideas?

**Bobby_M** · 12-21-2009, 02:09 PM

It sounds like you have more dead space in this one which makes sense. Deadspace is the volume of liquid (wort in this case) that remains in the tun after draining. That's sugar left behind. You can do a test with no grain in. Just fill it with about 3 gallons of water, drain it as you would a mash runoff, and measure how much liquid remains behind. Does your manifold sit directly on the bottom? How deep did you make the slots?

wildwest450 · 12-21-2009, 02:22 PM

My extreme cooler has zero dead space because the spigot is recessed in the bottom. I believe you will have 10 different results with 10 different coolers, plus the braid to manifold difference, although I get 83% with a cpvc manifold.

nicadrick · 12-21-2009, 02:43 PM

Quote:

Originally Posted by Bobby_M

It sounds like you have more dead space in this one which makes sense. Deadspace is the volume of liquid (wort in this case) that remains in the tun after draining. That's sugar left behind. You can do a test with no grain in. Just fill it with about 3 gallons of water, drain it as you would a mash runoff, and measure how much liquid remains behind. Does your manifold sit directly on the bottom? How deep did you make the slots?

Bobby, thanks for the instant response. I'll do the test and let you know. The manifold is flat on the bottom. Slot depth is random since I eyeballed it with a cutoff wheel. What should the depth be? Mine are generally 1/4 to 1/2 the pipe's (1/2") diameter. I suppose the only missing volume is where outlet pipe angles down into the drain. In the extreme cooler the drain is slightly below the grade of the main cooler bottom. I guess I can slot that section as well.

I am also questioning by own methods at this point. With my rounder, I have been recirculating the vorlauf until clear manually ala a pitcher, then once clear a complete runoff no additional water. Then I would close the valve, add water, stir, settle, recirculate til clear, drain again. Repeating until I get to preboil volume.

I did all the same with the rectangular, only this time I have a pump, no ladder, no pitcher.

wildwest450 · 12-21-2009, 02:48 PM

Quote:

Originally Posted by nicadrick

I am also questioning by own methods at this point. With my rounder, I have been recirculating the vorlauf until clear manually ala a pitcher, then once clear a complete runoff no additional water. Then I would close the valve, add water, stir, settle, recirculate til clear, drain again. Repeating until I get to preboil volume.

I did all the same with the rectangular, only this time I have a pump, no ladder, no pitcher.

Nothing wrong with a split batch sparge, that should maximize your gravity.

**Bobby_M** · 12-21-2009, 03:09 PM

Another question is if you had a length of tubing on the bulkhead/valve while draining. That helps suck the last of the wort out towards the end due to siphon effect.

**Cpt_Kirks** · 12-21-2009, 03:39 PM

A trick I have found is to slightly elevate the front of the MLT on the last sparge. That enables the syphon to operate a little longer. I went from nearly a half gallon being left behind to a little over a cup.

nicadrick · 12-21-2009, 03:55 PM

Quote:

Originally Posted by Bobby_M

Another question is if you had a length of tubing on the bulkhead/valve while draining. That helps suck the last of the wort out towards the end due to siphon effect.

MLT is at waist height with about 5 feet of hose going to the pump inlet. Pump is located at least a foot below the MLT and kettles. Does that answer your question?

nicadrick · 12-22-2009, 02:14 AM

Quote:

Originally Posted by Bobby_M

It sounds like you have more dead space in this one which makes sense. Deadspace is the volume of liquid (wort in this case) that remains in the tun after draining. That's sugar left behind. You can do a test with no grain in. Just fill it with about 3 gallons of water, drain it as you would a mash runoff, and measure how much liquid remains behind. Does your manifold sit directly on the bottom? How deep did you make the slots?

Bobby, I did the test you suggested. I found that a good 1/4" of liquid was left in the bottom of the tun. I took a look at my "manifold to drain" connection and added some slots at the lowest drain section. I put it back together, opened the drain and now there is only a few tablespoons of liquid left behind.

Here are some pictures of the revised manifold. I guess I better schedule another brew day to test it for sure,

Full view of the manifold

View of the added slots.

Thanks for all you do!

Cheers!

**Wade E** · 12-22-2009, 02:33 AM

Ah, good to the last drop. Thats about what i end up with in mine. It took 3 times of playing around before soldering so that I could end up with those same results.