Mash tun dead space

[RNBEERGUY]

hey guys about to start all grain brewing bought a new mash tun BeerSmith and water volume apps are asking for my dead space on mash tun what is that and how do I figure it out I read palmars book just having a hard time understanding

 

[beermanpete]

Dead space is the volume of liquid that does not drain out from the mash tun. To measure the dead space put a gallon or two of water in the tun and drain it out through the spigot without tipping the tun. Next, collect and measure all the water remaining in the tun. This is your dead space volume.

 

[RPh_Guy]

@beermanpete offers a good suggestion but it might overestimate the dead space because grain might take up some of that volume depending on your setup (e.g. whether you have a false bottom). ... And I tip mine so I don't lose as much.

A simple volume measurement pre-boil will help determine the absorption and mash tun dead space.
My first guesses were pretty far off but after adjusting loss predictions based on these measurements my second brew was dead-on.

I think the calculators are overly complicated. Your main losses are 1. grain absorption, 2. mash tun dead space, and 3. boil-off.
All other losses should be zero unless you specifically know you're losing volume somewhere else. Everything from my kettle goes into my fermenter.

Cheers & welcome to AG, it's a lot of fun!

 

[kh54s10]

@beermanpete offers a good suggestion but it might overestimate the dead space because grain might take up some of that volume depending on your setup (e.g. whether you have a false bottom). ... And I tip mine so I don't lose as much.

A simple volume measurement pre-boil will help determine the absorption and mash tun dead space.
My first guesses were pretty far off but after adjusting loss predictions based on these measurements my second brew was dead-on.

I think the calculators are overly complicated. Your main losses are 1. grain absorption, 2. mash tun dead space, and 3. boil-off.
All other losses should be zero unless you specifically know you're losing volume somewhere else. Everything from my kettle goes into my fermenter.

Cheers & welcome to AG, it's a lot of fun!

Beersmith treats mash tun deadspace, and grain absorption as different measurements. You don't want to try to compensate for them. My cooler mash tun has a braid and I tip it, so my mLauterash tun deadspace is set at .1 gallon. Just because it is usually still trickling when I stop draining.

 

[RPh_Guy]

Beersmith treats mash tun deadspace, and grain absorption as different measurements.

Yes you are right, but the sum of dead space plus absorption can be easily measured by checking pre-boil volume.
I simply spilt the loss estimate between the two, estimating 0.125 gal (= 0.5qt = 2 cups) as dead space in my cooler with screen. I think the method suggested by beermanpete is a reasonably good starting point for dead space.

A precise measurement of dead space could be obtained by either dumping out the mash tun or turning it upside down to find how much liquid drains out (or alternately measuring the weight of grain after the liquid is drained to precisely determine absorption). I'm satisfied enough with my estimates to not need this higher level of precision.
Ask 10 brewers how to do something and you'll get 11 opinions!

@RNBEERGUY
Don't worry about it too much. If your pre-boil volume is too high you can just boil it longer and if it's too low you can top-up with water pre- or post-boil.
If making adjustments on hot water, keep in mind mash-temp water will shrink by about 2% and boiling water will shrink by about 4% when cooled to pitching temperature.
My first batch I overestimated losses & had to boil longer to hit my target volume and O.G.
Even if your volume is off-target and you don't adjust, your O.G. will just be off-target; not a huge deal.

Hope this helps!

 

[kh54s10]

I set the amounts in BS but when I sparge, I measure the drainings from the mash, fill the tun with about half what I need to get my pre-boil volume, measure again and sparge with enough to get my pre-boil volume. By having the right numbers in BS I get the right OG (usually).

 

[mongoose33]

@RNBEERGUY
Don't worry about it too much. If your pre-boil volume is too high you can just boil it longer and if it's too low you can top-up with water pre- or post-boil.
If making adjustments on hot water, keep in mind mash-temp water will shrink by about 2% and boiling water will shrink by about 4% when cooled to pitching temperature.
My first batch I overestimated losses & had to boil longer to hit my target volume and O.G.
Even if your volume is off-target and you don't adjust, your O.G. will just be off-target; not a huge deal.

Hope this helps!

You beat me to this....in the end, it will be beer, and probably decent beer. After the first time, you can figure out exactly what you have for dead space.

I've recently started using a pump and a conical; there are dead-space losses all through the system (deadspace in mash tun, in the pump and hoses, in the remainder left in the kettle, and in the beer I can't rack out of the conical. I've increased my water volume from 7.25 to 8 gallons, and increased my grain bill by about 10 percent to account for this.

I'm not suggesting OP do that--instead, brew one, see what you get, and then you can adjust.

 

[beermanpete]

I simply spilt the loss estimate between the two, estimating 0.125 gal (= 0.5qt = 2 cups) as dead space in my cooler with screen.

This will result in errors on batches that have a different size grain bill. The dead space does not vary batch to batch but grain absorption will (unless you always make the same recipe).

 

[RPh_Guy]

This will result in errors on batches that have a different size grain bill. The dead space does not vary batch to batch but grain absorption will (unless you always make the same recipe).

I didn't explain well enough. My first batch I lost 6qt during the mash/sparge with 13lb grain. I simply estimated 0.5qt as dead space and the remainder 5.5qt as absorption (0.42qt/lb).

The margin of error depends on how far off my estimate is from the true dead space volume... my second attempt using these numbers (and 14lb grain) was highly accurate so I'm not too worried about it. My next brew is a Berliner with 6.8lb grain, so I'll see how well my numbers hold up to variation, and adjust if necessary.

EDIT: Your method would probably have helped me with my first batch. It provides a reasonable estimate. My point was that it is JUST an (over-)estimate for a system like mine where the dead space has grain in it.