Sparging to OG problem hitting number for consitince?

[thebrewersgrimm44]

I was recently told that if want to be consistan and hit my numbers everytime, I should sparge to my og, mark my boil kettle so after boiling I fill to the mark line with water to get exactly my og and proper volume. This confusses me. Does anyone have any ideas on how to do this?

 

[thebrewersgrimm44]

I was recently told that if want to be consistan and hit my numbers everytime, I should sparge to my og, mark my boil kettle so after boiling I fill to the mark line with water to get exactly my og and proper volume. This confusses me. Does anyone have any ideas on how to do this?

I beleive I have answered my own question just after I wrote this.:cross:

 

[LKABrewer]

You need to know how many points you need. Think of points as a measure of the sugar content in your wort.

Gravity x Volume = Points

For example, if you add 1# DME (40 points) to 1 gallon of water, you will get an SG=1.040. If you then add 1 additional gallon of water, your SG=1.020. Boil down to .5 gallons, and SG=1.080. The sugar content is not changing, but the points/volume, expressed as SG, will change as the volume of sugar changes.

To calculate the points in your batch, multiply the flame-out volume in your kettle by the expected SG. If you plan on having 5.5g @ 1.055 in your kettle at flameout: 5.5 x 55 = 302.5 points expected.

Knowing that SG1 x V1 = SG2 x V2, you can calculate what SG is needed at different volumes. If your first runnings are 1.062, you will only need 4.9 gallons of wort (302.5 / 62 = 4.88). If you have 4.5 gallons in your kettle @ 1.067sg (4.5 x 67 = 301.5), you have enough points for your beer. Once you have your total points in the kettle, you are better served by topping off with water than continuing sparging.