Include dead space in grain to water ratio?

[Orange606]

My current e-BIAB system (recalculating) has significant dead space, a little over 4 gallons. I suppose in most systems the dead space is minimal and generally does not impact the mash, but in systems with significant dead space should I include the volume of the dead space in the grain to water ratio? Alternatively, should I separately consider the ratio of grain to total water, and grain to water within the grain holding area? I am trying to determine the impact of having a large dead space and the impact of more or less water in addition to what is needed to fill the dead space. Please let me know if you have thoughts or references that address this issue.

 

[adamc]

You gave 4 gallons of dead apace? As in, you add 5 gallons of water and, grain and only 1 gallon touches grain?

Absolutely consider it in your water addition calcs.

That is a hell of a loss. What type of MLT are you using?

 

[Orange606]

Inverted keg, water heater element, false bottom above water heater element. I don't loose the 4 gallons, from a draining standpoint I loose nothing due to the center bottom outlet. Since my system is BIAB I use the total expected water volume during the mash which includes compensation for absorption and boil-off. Generally I use 9-10 gallons for a 5 gallon batch. My brew house efficiency is around 75%.

 

[afr0byte]

Inverted keg, water heater element, false bottom above water heater element. I don't loose the 4 gallons, from a draining standpoint I loose nothing due to the center bottom outlet. Since my system is BIAB I use the total expected water volume during the mash which includes compensation for absorption and boil-off. Generally I use 9-10 gallons for a 5 gallon batch. My brew house efficiency is around 75%.

You must boil off quite a bit. I use 9-10 gallons for 6 gallon batches.

 

[chickypad]

No references for you, only what I do. In a 15 gallon SS kettle tun I have 2 gallons dead space during mash (with a diptube I don't lose it during lautering). I usually figure 1.25 qt/lb, then add my 2 gallons. That tends to put me around 1.6 qt/lb overall. Not sure what is right but because both these ratios are within normal mashing parameters I feel okay. I don't want to go thicker than that because I am recircing through a HERMS.

 

[billl]

The grain doesn't know you have "dead space". It's only concerned with the relative concentration of enzymes.