# Bad Efficiency into boiler...can I just boil longer?

### Help Support Homebrew Talk:

#### Kayos

##### Well-Known Member
I just had the easiest brew day thus far...until I read my eff. into boiler was 46%. I have no idea why that would be, but for now, can I just boil longer until I get a reading closer to where it should be? Will the water boil off?

#### kenche

##### Well-Known Member
Yes, you can boil longer to hit your intened OG.

You should also be able to calculate how much you have to boil off. The amount over fermentables is constant, only the volume is variable.

V1*G1 = V2*G2

Where
V1 = preboil volume
V2 = postboil volume
G1 = preboil gravity pts (ie, 1.038 = 38 gravity pts)
G2 = postboil gravity pts (ie, 1.056 = 56 gravity pts)

So, if you have 6.5 gals of 1.040 wort pre-boil, and you are shooting for 5.5 gals post boil:

6.5*40 / 5.5 = 47.2727 -> 1.047 post boil gravity.

or

If you want to hit 1.056 OG, you need to boil it down to:
6.5 * 40 / 56 = 4.624 -> 4.624 gallons wll give you 1.056 OG wort.

The above calcuations were copied from a realbeer posting.

OP

#### Kayos

##### Well-Known Member
Very cool, thanks! Guess 4.5 gallons will have to do today.

#### ajf

##### Senior Member
Did you stir the wort well before taking the sample? If not, you will get a low gravity because all the heavy early runnings are sitting in the bottom of the kettle.

-a.

OP

#### Kayos

##### Well-Known Member
I did stir. It boiled down in about 90 minutes total. The only thing I can think is that the crush was bad. My base malt came in a big bag (online order) and I added everything else to the bag then poured it into my strike water. I never looked at the crush on it. I ended up with a little over 4.75 gallons in my primary with a OG right on. It was supposed to be a 5.5 gallon batch. I guess I will have to inspect next time.

One other thing. This was a stout and The last half gallon of runnings from my sparge was lighter than the rest. Could this have been a reason for the off eff? I was thinking it was a good sign that I got all the sugars, but maybe not.....

#### WBC

##### Well-Known Member
I keep seeing this loss of efficiency posted daily and wish brewers would do their homework before brewing. Yes I have made my mistakes too and that is how I learned but if you have brewed 4 times and still have a problem with efficiency then keep reading.

If you have crushed grain that is not opened as much as needed you can mash longer and or crush again if it is barely open. Longer mash times give the water a chance to get into the grain and modify the starches. I have gone as much 2 hours and had great results in a 10 gallon Rubbermaid cooler/mash tun.

My Barley Crusher is a Crank And Stein set at .035 inch. This really opens most of the grain and I have tried closer but it is almost a stuck sparge (with a SS false bottom) when I brew a really big batch of grain ie: 25 lbs grain to 1qt per LB of grain. This fills the 10 gallon cooler mash tun to the top and is a very thick mash so I always batch sparge 3 times if batch sparging and get 14.5 gallons for a 12 gallon batch. This gives me extra wort to add as the boil evaporates water. I end up with my full 12 gallons of post boil volume. I can get 80% to 85% efficiency using this method of extra mash time and sparging 3 times. I also throttle the last sparge at the mash tun outlet very slow on the last sparge to get all the goodness I can when I have a large grain bill like 25 LBS.

Note: I only sparge 2 times when doing 18 to 20 LBS of grain and get very good efficiency results. I know I need a bigger mash tun and also know that it would be a lot less work if I fly sparged in a round 15 or 20 gallon round insulated mash tun. Rectangular Mash tuns have a less uniform sparge and need to have a good design on the sparge drain manifold and fly sparge system to have a uniform sparge.

#### Bernie Brewer

##### Grouchy Old Fart
Um,just checking, did you account for the higher temperature of the runnings when you took your reading??? If you didn't then adjusting for temp might put you right on target.......

#### FlyGuy

##### Well-Known Member
I know it is too late now, but did you scale back your hops to compensate for the reduced gravity/volume? If you don't do this, then your beer will turn out more bitter than you expected. Often this can be trickier to do than it sounds because the bitterness extracted from the hops depends on the volume of water in the boil, the length of the boil and gravity of the wort.

As a side note, it is generally much easier to keep a bit of DME on hand in case you miss your extraction target. Take a pre-boil gravity reading to see, and if it is too low, you can add a bit of DME to get it up to the intended gravity.

OP

#### Kayos

##### Well-Known Member
WBC said:
I keep seeing this loss of efficiency posted daily and wish brewers would do their homework before brewing.

Wow...I see an EAC diploma in your future. Take it easy, brother. I am a research junkie and did do my homework. This is also not my first batch, friend. For reference, I did a mashout and also a double sparge. I compensated for temp on my hydro readings and learned my lesson on checking my crush as stated. This was from B3, and I have never had a problem with them in the past.

Thanks for the great input, FLYGUY..it is always appreciated from you. I will keep DME next to me from now on. Luckily, I was on the low side of the IBU's, so it should still be alright. I get 36 on Brewsmith after adjustments, still good for my dry stout.