I just mashed a recipe that had a target OG of 1.045-1.050. After boil my OG was 1.0362. Struck at 164.5 deg, sparged out roughly the same temp water. 3.5 gallons of water to mash and 6 gallons to sparge. Had 4.75 gallons after boil into the fermenter and decided to leave it at that. During mash noted temp initially at 160, that settled and held at 150-152 for the 1hour I mashed. My sparge method was to transfer wort back into the sparge until I had 0.5-0.75" of relatively clear wort over the grain. I then opened the valve and let that trickle into my boil container while simultaneously trickling sparge water in at the same rate until all the sparge water was in and then drained the mash tun. I had 6.75 gallons going into the boil and 4.75 after. I'm reasonably new at all grain and haven't quite figured out why my OG's have always come out lower than expected. Suggestions?
"I'm reasonably new at all grain and haven't quite figured out why my OG's have always come out lower than expected. Suggestions?" Low efficiency, most likely caused by bad crush, too thick of mash, not enough stirring if batch sparging, mash tun design, incorrect assumptions on brewing software, channeling when fly sparging, incorrect volumes, bad thermometers/hydrometer readings, etc. I'm not really sure how you are sparging...batch/fly...something in between?
Post the full recipe so we can see what your expected and actual efficiencies were. My first guess as to why your efficiency is coming up low would be either a poor crush, channeling while sparging or a combination of the two.
2 gallons lost to evaporation seems like a lot. How long did you boil for? Also, if your OG after 2 gallons of evap was still that low it must have really low preboil. Can you post a picture of your mash tun set up including a picture of the inside? Was the 160 temp your strike water or after dough-in (mixing with the grains)? Is it possible to "shock" the enzymes to where they are not converting the starch to sugar? As itsjustzach mentioned, posting the recipe would help. 160 to 152 seems like a big heat loss if your cooler was near 70-75 degrees.
Mash Tun is a rubbermaid cooler. I took a stainless steel mesh from a water heater line as my screen so there is no false bottom. The line coils around twice in the bottom. Every thing flows really nicely. The 165 deg water is my strike water. The grain was at 70 degrees. I don't know what the cooler temp was...I'll record that next time. As far as losing 2 gallons of water. I boil on a large diameter kettle that has alot of surface area which tends to evaporate much faster than my smaller stove top kettle. I boiled exactly 1 hour and am surprised as well that there was this much boil off. The recipe can be found here. http://www.tastybrew.com/newrcp/detail/596
If I understand your method correctly, it sounds like you are basically fly sparging, so perhaps the most likely explanation would be channeling, especially if you were doing it 'by hand.' Try batch sparging next time and see if that doesn't fix it. Also, it's always a good idea to have some DME on hand when you're all grain brewing, I think, so you can add to the boil if necessary to make up for fluctuations in efficiency
You would be better off with having a circle .707 of the radius of the cooler, that makes the inside and outside areas equal. Put in a center take out, so that the thing looks like the Greek letter Theta, and the take out at the middle of the crossbar. I would make the crossbar out of copper pipe, and the plumbing to the valve out of copper. Hope you can follow, a picture would be better, but I don't have that set up.
Hey thought I would follow up this post. My adjusted OG was 1.036 , but my adjusted FG was a fantastic 1.0056 ending up with a respectable 4.04%. By adjusted I mean for temperature (78.0 for the OG and 72.1 for the FG. The beer smells great and even tastes good flat with no bottle seasoning. Looks like it will be really good in two weeks or so. Brewing the same recipe next week and will try both the theta idea to prevent tunneling and batch sparging.
