I just did my 4th brew, my OG was lower than expected, and I'm looking for help with process improvements. I'm doing an all grain process. I have an 8gal kettle, a 2gal kettle, and a 0.5gal kettle. For the mash tun I have a 10gal home depot converted cooler with ball valve control spigot.
My process is as such:
Day before - fill the kettles with water, let them sit 24 hours with a Campden tablet shared between the pots.
Heat 6.5gal of water in the 8-gal kettle to 160F. Warm the mash tun, check the water is still 160F.
- Dump the grain into the mash tun,
- Tip the 6.5gal of 160F water into the mash tun. Actually this starts out by moving it 1 quart at a time as I'm unable to safely dump the entire 6.5 gal of hot water in one shot anyway, and I heard it was better to add it slowly to the dry grain.
- Stir with my giant 24" spoon to check no air pockets (just at the start)
- Then leave for an hour. (temp remains constant for the hour within 150-155F - typically around 152F)
- Recirculate until the flow of wort is relatively clear
Drain until empty back into the 8 gallon kettle - this typically yields about 4.2 gal.
Meanwhile I've heated the 2 gal kettle and 1/2 gal kettle to 170F
- Dump 2.5gal of 170F water into the mash tun to sparge
- Stir briefly
- Wait 15 minutes
- Recirculate until flow of wort is relatively clear
Add this to the kettle until the kettle is back up to the 6.5gal mark
Boil for an hour adding hops and Irish moss as prescribed
- 45 minutes into the boil add the wort chiller to sanitize it (no water flow connected).
- Transfer to the sink, connect the water flow to the chiller, also add blocks of ice into the sink
- Stir the wort with the chiller and drop the temperature down to 70-75F
- Siphon to 6.5 gal better bottle
- Test OG - this is usually done with the final, rather trubby, bit of the wort.
- Pitch yeast
- Wait until airlock starts to bubble, then chill to prescribed fermentation temp in a temp controlled modified-freezer.
My recipe involved 11 lbs of grain for a pilsner, with an expected OG of 1.049 mine measured 1.044, so a little lower than expected. My previous brew called for an expected OG of 1.062 but my process only yielded 1.051 so lower still.
I'm wondering - are my OG's lower because I'm using a higher volume (6.5gal for the boil) than a typical recipe expects?
Specifically, with a 5gal recipe - what exactly is supposed to be 5gal? The pre boil volume, the post boil including trub volume, the volume initially put into the fermenter without the trub, or the bottled volume? I've been trying to target 5gals into the bottles, my last round yielded 4.66gal. But perhaps this is my misunderstanding and might completely explain my OG delta?
MANY thanks for reading this long one!