mashtun deadspace

[darkstar79]

Tomorrow I will be brewing my 2nd all grain. I just kegged the first one I did today, an Irish red and I am pretty happy with the results! The first brew session I did not account for the deadspace in the mashtun. I am using a 8 gallon megapot with a false bottom. What I did tonight is measured the amount of water underneath the false bottom which is 1.75 galllons. I figured this to be my deadspace, is that correct?

 

[Yuri_Rage]

No. Dead space is equal to the amount of wort leftover after lautering (i.e., the amount that you cannot collect). Figure it by calculating the volume below the drain in the MLT + the volume of the tubing/plumbing that will not be empty at the end of wort collection.

 

[jmo88]

The dead space is the water that doesn't come out during the runnings.

To figure the dead space just fill with a couple gallons of water and let it drain just like you would when you brew. Whatever doesn't come out is your dead space.

1.75 gallons seems like a lot.

 

[darkstar79]

ok, last time there seemed to be some runnings left under the false bottom. I must have not drained it all the way. Is it ok to tip the kettle a little to let it all drain?

 

[darkstar79]

one question I have that I dont understand either is if about 1.75 of gallons of water are underneath the false bottom, it seems to me like I am missing that much water to mash the grains. the reason behing my though is that amount of water wont mix with the grains to make the mash becaue its under the false bottom and the grain is resting on top. Does it not matter since the runnings drip through there or an I overthinking this?

 

[jmo88]

one question I have that I dont understand either is if about 1.75 of gallons of water are underneath the false bottom, it seems to me like I am missing that much water to mash the grains. the reason behing my though is that amount of water wont mix with the grains to make the mash becaue its under the false bottom and the grain is resting on top. Does it not matter since the runnings drip through there or an I overthinking this?

If you are batch sparging and can get extra wort out of the mash tun by tilting it, then tilt it. The less dead space the better.

If you are recirculating after the mash then the unmixed water under the false bottom will get homogenized before the sparge.

 

[shortyjacobs]

ok, last time there seemed to be some runnings left under the false bottom. I must have not drained it all the way. Is it ok to tip the kettle a little to let it all drain?

Yes.

one question I have that I dont understand either is if about 1.75 of gallons of water are underneath the false bottom, it seems to me like I am missing that much water to mash the grains. the reason behing my though is that amount of water wont mix with the grains to make the mash becaue its under the false bottom and the grain is resting on top. Does it not matter since the runnings drip through there or an I overthinking this?

Are you recirculating? If yes, then that extra space doesn't matter, (as noted by others). If no, then you should add an EXTRA 1.75 gallons of water to your tun to account for this and still hit your mash thickness target. I am not sure how beersmith, or other software, accounts for this.

 

[steakandale]

I just made my Rubbermade cooler MLT. I looked at the level of the braid and where the spigot-hole is and wonder if we cant put something in the very bottom to form a layer and take up that dead space? Something food-safe and easy to clean and sanitize. Has anyone come up with a good solution for that?

 

[shortyjacobs]

I just made my Rubbermade cooler MLT. I looked at the level of the braid and where the spigot-hole is and wonder if we cant put something in the very bottom to form a layer and take up that dead space? Something food-safe and easy to clean and sanitize. Has anyone come up with a good solution for that?

Some type of high temp foam maybe? Food-safe is the key...sanitization is moot, as it's preboil...

 

[jmo88]

I just made my Rubbermade cooler MLT. I looked at the level of the braid and where the spigot-hole is and wonder if we cant put something in the very bottom to form a layer and take up that dead space? Something food-safe and easy to clean and sanitize. Has anyone come up with a good solution for that?

Yes. Ditch the braid and make a cpvc manifold with slits on the bottom. Safe at mash temps and virtualy no dead space due to the manifold sitting flush on the bottom. The runoff tubing connected to the spigot creates a vacuum to get out all the wort.

 

[steakandale]

Hmm that might not hold up and god knows what patroleum products are in it. I was thinking along the line of glass tiles, or glass beads like they fill vases with? or how about plastic cutting board cut into haves or thirds the shape of the tun bottom?

 

[jmo88]

Hmm that might not hold up and god knows what patroleum products are in it. I was thinking along the line of glass tiles, or glass beads like they fill vases with? or how about plastic cutting board cut into haves or thirds the shape of the tun bottom?

??? I'm not brainstorming. This is proven a safe and effective method for many brewers. Chlorinated PVC is quite safe at mash temps.

 

[jmo88]

Check out post number 7. https://www.homebrewtalk.com/f51/cooler-mash-tun-128216/

sorry for the highjack.

 

[darkstar79]

Yes.



Are you recirculating? If yes, then that extra space doesn't matter, (as noted by others). If no, then you should add an EXTRA 1.75 gallons of water to your tun to account for this and still hit your mash thickness target. I am not sure how beersmith, or other software, accounts for this.

I vorlauf to make sure the grain is settled, so yes I am recirculating. Thanks for the help!

 

[steakandale]

I wasn't clear who I was replying to, I don't think the foam is a very robust solution. I didnt see your post until I went back to see what happened. I'll search and read up on that, thanks!
That will take some redoing of my bulkhead so I'm curious how that was solved. That braid was a pain, and may get replaced.

 

[shortyjacobs]

I vorlauf to make sure the grain is settled, so yes I am recirculating. Thanks for the help!

I was talking about continuous recirculation, which would mean the wort is continually circulated through the grain. Vorlaufing is only done at the end of the mash, so your grain doesn't see that bottom water during the mash, meaning it doesn't "count" towards your qt/lb calculations for strike water. You need to add extra water to account for that false bottom.

 

[darkstar79]

I was talking about continuous recirculation, which would mean the wort is continually circulated through the grain. Vorlaufing is only done at the end of the mash, so your grain doesn't see that bottom water during the mash, meaning it doesn't "count" towards your qt/lb calculations for strike water. You need to add extra water to account for that false bottom.

Ok, Im 30 minutes into the mash now without accounting for the 1.75 gallons of water that sits under the false bottom that the grain does not come in contact with. Should I just add 1.75 gallons more of sparge water?
In the future when I account for the extra water under the false bottom should I subtract that amount from what I put into the kettle, or subtract that amount from the sparge water?

 

[shortyjacobs]

Ok, Im 30 minutes into the mash now without accounting for the 1.75 gallons of water that sits under the false bottom that the grain does not come in contact with. Should I just add 1.75 gallons more of sparge water?
In the future when I account for the extra water under the false bottom should I subtract that amount from what I put into the kettle, or subtract that amount from the sparge water?

Say you need 3.5 gallons strike water and a total of 5 gallons sparge water, giving you about 7 gallons into the kettle.

You need to add (3.5+1.75) gallons to strike. Then, subtract that 1.75 gallons from the sparge, (5-1.75 = 3.25 gallons sparge water). This will still give you 7 gallons into the kettle.

Or just live with thicker mashes, since this doesn't leave much water for sparging. For this mash, I'd just RDWHAHB.

 

[darkstar79]

Ok cool thanks! I will just leave it this time

 

[peter78]

Ok cool thanks! I will just leave it this time

So, did you find a solution. I know it's been some time. I'm having the same problem right now with 2 gal space under the FB. I was thinking adding river rocks under it.

http://www.ebay.com/itm/30-lbs-Blac...444?pt=LH_DefaultDomain_0&hash=item53ebfdffe4