My first two BIAB brews have both produced lower than expected OG. Both had around 70% efficiency on the preboil reading so I would say it isn't a mash issue.
For my first brew I assumed that it was boil issues, on todays brew I left the therm on all through the boil and it displayed 100C for the full 90 mins.
Taking an hydrometer reading at the end gave 1056 (against a predicted 1060) which isn't too bad but I also only transferred 17.5l rather than the planned 20l. Here I assume that my volume calcs are off, to compensate I could up the water volume but this would lead to a much lower OG (as in brew 1) unless I also up the grain bill. Help?
Is there a way to use the OG and preboil reading to calculate volume loss due to evaporation?
There is a blog of my brewday at http://www.aleandstuff.blogspot.co.uk/
Evaporation and trub losses?
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jaberry
Re: Evaporation and trub losses?
Join http://www.biabrewer.info as well as Jim's they have a specialist BIAB spreadsheet which will give you an evaporation figure. The spreadsheet 'biabacus' is in beta form BUT is basically complete and very good
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BigAde
Re: Evaporation and trub losses?
I've had a look at the biabacus spreadsheet, the only way I can get to make the figures fit my actual measured values is by lowering the value of evapouration.
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Cpt.Frederickson
- Hollow Legs
- Posts: 454
- Joined: Wed Jul 04, 2012 7:54 pm
- Location: BIAB in the Shed, Maidstone, Kent
Re: Evaporation and trub losses?
Try using their 'old' standard calculator. I've used it since I began and found it very helpful. Some other things to consider is the type (brand) of grain you are using, how fine is the grind, how old etc.
Since using Crisp Pale malt my efficiency has gone up. Got 83% post boil yesterday (was 85% pre boil). Your mash efficiency should always be a little higher than your EOB efficiency, so if it is low you're going to run into problems.
Since using Crisp Pale malt my efficiency has gone up. Got 83% post boil yesterday (was 85% pre boil). Your mash efficiency should always be a little higher than your EOB efficiency, so if it is low you're going to run into problems.
The Hand of Doom Brewery and Meadery
Fermenting -
Conditioning - Meads - Raspberry Melomel yeast test, Vanilla Cinnamon Metheglyn, Orange Melomel.
Drinking - Youngs AAA Kit; Leatherwood Traditional Mead, Cyser, Ginger Metheglyn.
Planning - Some kits until I can get back to AG, then a hoppy porter, Jim's ESB, some American Red.
Fermenting -
Conditioning - Meads - Raspberry Melomel yeast test, Vanilla Cinnamon Metheglyn, Orange Melomel.
Drinking - Youngs AAA Kit; Leatherwood Traditional Mead, Cyser, Ginger Metheglyn.
Planning - Some kits until I can get back to AG, then a hoppy porter, Jim's ESB, some American Red.
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Twistedfinger
- Hollow Legs
- Posts: 366
- Joined: Wed Nov 10, 2010 10:35 pm
- Location: From Darlo living in Bolton and feeling damp !
Re: Evaporation and trub losses?
Have you checked your hydrometer is accurate ? Try it out in plain water. I've got one that is 2 points out ( its now a spare).Taking an hydrometer reading at the end gave 1056 (against a predicted 1060)
Plus: at
Was this a sample taken at flame out or after chilling ? The reason I ask is because if you took a hot sample from the kettle at flame out and the wort had settled there is a chance that the wort at the top could have been at a lower gravity than the bottom.the end gave 1056