As someone who has also been suffering from high yield loss lately, this thread is a great reminder of just how important it is to take notes and measurements every step of the way...something I don't do very often but will from now on.
If I may inject a few questions of my own here...
Originally Posted by heckels
Seems like there's a few issues here.
First, what is your target preboil volume? That should be your target post-boil volume + your boil off volume + volume accounted for trub and transfer loss.
Once you have that figured out then you can determine what your preboil gravity (SG) should be and where your efficiency is actually falling.
Until you know these things changing your equipment won't really help you. Also, trying out some software such as BrewTarget (free) will really help you figure out your system, target volumes, gravities, etc.
Preboil Volume - Slightly confused how this number should derived and at what stages you should be taking these readings. Could you provide some additional details here? I've generally done a reading after the boil and chilling of the wort to get an OG reading to compare against the FG before bottling. Should I be taking readings after mashing/sparging as well? Are there ball park figures for boil off volume and trub/transfer loss? What about hop/grain absorption? Thanks so much for any additional details you can provide here!
Also, is it bad to cover the initial grain mashing or are we just talking about the boil itself?