too much preboil volume

[blanchmd]

Howdy -- I mash in a rectangular cooler, batch sparge, 1.25 quarts per gallon mash ratio, and I use this calculator and follow whatever volumes it gives http://www.brew365.com/mash_sparge_water_calculator.php

I consistently am getting about an extra gallon of preboil wort volume and it throws off my OG for sure . Thoughts?

Thanks

 

[McKnuckle]

There are only 4 factors to consider between the cooler and kettle in this instance:

- Volume of water used for the mash
- Grain absorption (about 0.11 gal/lb)
- Volume lost to dead space in the cooler, if any
- Volume of water used for the batch sparge

One gallon variance is a lot. You should just measure these amounts more carefully. And don't forget - you only lose water to grain absorption and dead space ONCE. You should be collecting every drop of the sparge water.

Pre-boil Volume = (Mash Vol + Sparge Vol) - (Dead Space + (lbs x 0.11))

 

[RM-MN]

Quit using that calculator and use this simpler one instead.
Drain your mash tun. Measure the approximate amount of wort collected. Subtract that from your desired pre boil amount. Use that amount to sparge with.

Since at the end of the mash and you drain your tun, your grains will be saturated they won't absorb any more water. Whatever amount you use to sparge with should equal what you drain back out. Use cold water to sparge and if you aren't getting quite enough wort collected you can just dump in a little more water, stir and drain to get what you want.

 

[madscientist451]

The calculator has a line for "equipment loss" that is pre-set at 1.
Are you changing that to zero?