Pre boil kettle volume ?

Due to ending up with slightly less than 4 gallons in the fermenter (after my 1st and 2nd all grain attempt) I ask this question. After batch sparging until my kettle had about 6 gallons (it took 60 mins.) the water coming out of the mash tun was totally clear, telling me I have effectively cleansed the grain of all they've got. So, should I just stop sparging and add 1 gallon of tap water to the kettle to bring up my pre boil volume to 7 or maybe even 8 gallons or should I just run the HLT water through the grain until I reach 7 or 8 gallons.

Is it unheard of to start the boil with 8 gallons of wort for a 5 gallon batch? I heat my kettle with a 4500 watt heating element and I lose quite a bit due to evaporation. The heating element also prevents me from using a muslin bag unless I try suspending it which will be tough because it takes 3 gallons just to cover the element. Needless to say, the hop pellet trub slows down my wort flow through my 3/8 c-f chiller, and next time I will try whole hops.

As always, thanks for any help.

What is your sparging temps? How much is your grain bill and how vigerous is your boil? I get 8 gallons of wort to boil down to 5 gallons with an Average OG of 1042 from 9 Lbs of grain on my turkey frier setup. Can you adjust your boil so you don't lose as much? What SG are you stopping your sparge at? Oversparging will extract more tannins than you want in your brew.
Cheers

With batch sparging you generally don't worry about the SG of the runnings. You're running off the batch so fast (compared to fly sparging) that it's not as much of an issue for a standard two-batch run off. Since it's batch vs. continuous you can estimate the runnings for each discrete batch to stay roughly the same SG.

6g would be at least 1g shy of the target pre-boil volume I need to achieve 5g in my fermenter. I always shoot for 7g, and if my kettle would hold more I'd probably go for 7.5-8g. My evaporation rate is consistently 20-25% during boiling.

What you want to do is figure out how much pre-boil volume you want (say 7g), and then calculate your two batches so that they each result in roughly equal runoffs of 3.5g into your kettle. This will require 4.5-5g (estimate) for the mash due to grain absorption, and then a straight 3.5g for sparging in this example. You don't want to add extra water in the sparge batch and then just stop the runoff because you will then be leaving sugar in your tun. You want to runoff the entire batch, so calculating the volume required is important with batch sparging.

Also, as long as you hit your efficiency and target pre-boil volume, it's not problem to top up with water in the primary if you wind up boiling off more than anticipated.

Just because the runoff is clear, does not mean there isn't any fermentables in it. I've found doing two sparges (after the initial runoff) gives me better results. I start the boil around 7-7.5 gallons for a normal batch. I've also started using pH 5.2 in the sparge water to eliminate the tannin problem. I boil the sparge water while the mash is cooking to clear out any Cl, etc. and put it in a cooler. It tends to be around 185F when I sparge.

If you're going from 8 gallons down to 5, your boil is way too vigorous!

Sounds like you need to find a controller for your element so you can back offf the heat.

boo boo said:

Oversparging will extract more tannins than you want in your brew.
Cheers

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I don't think that this is necessarily true. The factors that affect tannin extraction are the sparge temperature and the PH of the sparge water.
I acidify my sparge water to a PH of about 5.7, and by the time the water hits the mash, it is 165 - 170 degrees. I always sparge until I hit the required volume (usually with about 6 1/2 to 7g of sparge water). With the PH adjustment, I don't get excess tannin extraction, but my efficiency does increase.

-a.

Thanks a lot guys! I still have a question about taking a gravity reading of the run off. When would you take it. Obviously the first 2 gallons of the run off are thicker and more dense than the last few drops. Do you take a sample early and later and then mix? Take 2 or 3 readings and average?

For this last batch I used a grain bill of 10 pounds and sparged with 182 water which caused the top 2 inches of the mast to be around 170. Is this ok. I have the intake and exhaust of the water set so slow that it takes about 1 hour to obtain 6-7 gallon in the kettle.

barside laundry said:

Thanks a lot guys! I still have a question about taking a gravity reading of the run off. When would you take it. Obviously the first 2 gallons of the run off are thicker and more dense than the last few drops. Do you take a sample early and later and then mix? Take 2 or 3 readings and average?

For this last batch I used a grain bill of 10 pounds and sparged with 182 water which caused the top 2 inches of the mast to be around 170. Is this ok. I have the intake and exhaust of the water set so slow that it takes about 1 hour to obtain 6-7 gallon in the kettle.

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Are you sure you're batch sparging as you indicate in your first post? Sounds like you are fly sparging. A batch sparge should take no more than 5-10 minutes per batch.

You need to take frequent readings of your run off as you near the end of the sparge.

As soon as you reach 1.010 or so, (some say 1.000) it's time to stop. That's the point where you may be leaching very evil tannins.