Very low OG

[supaphly42]

First all-grain batch. Details in this thread. Things seemed to go alright, until the boil. Not sure if it was because it was breezy, or because my kettle is too big and sits up about an extra 1-1.5" from the flame on my turkey fryer, or if that is underpowered, or something else (40qt aluminum kettle). I will probably try making a foil insulation blanket for it next time, and will look into getting the flame closer to the bottom.

Anyway, it took a long time to get to a boil, and never got a vigorous boil going, even wide open the whole time. Presumably, because of this I ended up with 6 gallons post-boil, instead of 5-5.5. I assume this is why my OG was measured at 1.046 after cooling, instead of the estimated 1.062.

So, my questions are first, what effect will this have? I pitched the yeast and prayed, haha. Anything I can do to help it along? And second, was it probably caused by the low boil and not enough boil-off, leaving too much water content? Should I just boil longer in the future if I have that issue, or something else?

 

[MoreHops]

I took a peek at your other thread but didn't see these bits:
What was your actual mash temp? And pH? Pre-boil gravity?
Your less-than-vigorous boil will have an effect on OG due to volume differences but to a limited extent (only a few grav points -- not 16 points worth). It sounds to me like you had problems with the mashing...
That, in conjunction with your boil, gave you a low efficiency...

 

[sidepart]

Well to answer your concerns first. You're not going to have as strong of a beer as before. Looks like you were going for an Irish Red. I'd say 1.046-1.055 is a good range for an Irish Red. If you pitched enough yeast for a 1.062 batch, you should have quite a healthy fermentation. Other than not hitting your post-boil OG, your concoction will quite literally will turn into beer. I don't sense any real negative effects other than a lighter color and reduced ABV %.

Now to the mechanics of it all. What kind of calculations did you come up with out of curiosity? What were you expecting pre-boil OG to be, and after the boil, what did you expect your volume to be? Also how are you mashing? 152F for 60 minutes, then batch sparging? What kind of efficiency were you using in your calculations?

If you got 6 gallons from your mash instead of 5-5.5 (assuming you're batch sparging) you may have just sparged too much wort out of your mash. Depending upon how much sugar you got out of a first and second running, the third may not have had much to offer. Any reason you didn't just stop draining your mash tun after reaching 5.5 gallons? As was said above though, 16 points seems a little high for this scenario alone.

If you measure your pre-boil gravity, you could mathematically calculate how much wort you'd have to boil off to hit your target post-boil OG. You'd have to consider a couple of things though. First being, you don't want to boil ALL of the extra wort off before your 60 minute hop addition because then you will end up boiling too much off. Second, your calculations may show that'd you'd have to burn off a significant amount of your wort which just isn't economical...so you'd have to compromise or just live with it.

Anyway...all that aside, I think you're on the right track. I'm going to guess that you collected too much wort and that's probably one of the factors. The second factor is that you may be getting low efficiency in your mash. So even if you collected your target amount of wort (for the boil) you may still have come in low on your pre and post-boil gravity. Not sure we can fully determine that until you try again though. The worst possibility related to efficiency is that your mash just didn't convert enough starches into sugar and you drained too early.

 

[supaphly42]

I didn't think to measure pre-boil gravity, will have to do that next time. It calls for an estimated pre-boil of 1.055. I mashed at 155 for 60 mins. Batch sparged. Took my liquid amount from beersmith. It called for boiling 7 gallons down to 6.5 (it says est. post-boil volume 6.5 galo, final volume into fermenter of 5.5 gal). I may have collected too much wort, I need to figure out where in my kettle it should come to (first time using new kettle, 40 qt compared to my old 10, haha).

 

[sidepart]

Based on what you mentioned, I'm betting our problem could be more efficiency related than anything else at this point. You collected less wort that the software told you to.

What efficiency did you use in the software? 73%?

Here are some mash things we can look at. Are you following a guide on batch sparging? Bobby M's all grain primer is pretty popular.

When you dump the grains into your cooler, how vigorously are you stirring the mash before closing the lid? Are you sure you're not getting any giant clumps of grain? How thick is your mash? 1.25qt/lb of grain? How about your batch sparges? Are you following beersmith's recommendations, or are you just dividing your sparge water in half and doing 2 equal sparges? I recommend doing the latter, I've had better luck with it. Again during the sparge process, are you vigorously stirring the water in before draining? What temperature is your sparge water before dumping it in the cooler? 180F is a good rule of thumb so that it brings your grain temperature up to the upper 160's to 170 before sparging.

 

[jCOSbrew]

After a few batches with the new kettle you will be able to determine the boil off rate (how many gallons you lose to evaporation in 60 minutes) and the desired pre boil volume to get 5 gallons into the fermentor. Mark your brewing spoon in 1/2 gal increments to quickly measure volume in the brew kettle.

If you had 1.046 OG at 6 gallons, you would have had 1.055 at 5 gallons, so you are probably <70% efficiency of less. To measure brewhouse efficiency, punch your grain bill, preboil volume, and SG into one of the online calculators. I use the one on brewersfriend.com