Undershooting/overshooting Og

[Doc]

The trials and tribulations of hitting the target OG.

Until the last couple of brews I've generally been withing a point each way of my target OG.
This weekend it has been all over the shop.
I've implemented some new kit into the brewery, but nothing that should overly affect the gravity of my beers (new burner and a counterflow chiller).

Yesterday I brewed a Saison and missed my target gravity in the kettle and hence at the end of the boil. I was out by 10 points which is the most I've ever been out since my first AG. I can put yesterdays brew down to the mesh bag I have over my manifold in my MLT, a slight back tilt on the MLT when sparging and too fast a sparge.
Today I brewed an Hourglass IPA. I overshot the gravity into the kettle, and hence my final OG. I overshot by 14 points (instead of 1.064 in the fermenter I got 1.078). The difference today was I fixed the mesh on my manifold, made the MLT flat, and slowed down my sparge.

I haven't run the numbers yet to get the efficiency of both brews, but my god what a variation.

Anyone else had similar situations recently ?

Beers,
Doc

 

[chiller]

Hi Doc,

The place to look is probably the burner [NASA?] they are exceptional burners but can be a touchy thing to control until you master the small differences between woahh!! and oh crap .

I think I did similar on my first couple of brews but it settled down quickly.

Now all you need is a heated mash tun and multi rest mashes and your efficiency will alter again.

Steve.

 

[Doc]

I know what you mean with the NASA burners.
I haven't had a boilover in ages and I had four this weekend :lol:
And all the neigbhours were looking to the skies for hot air ballons

Doc

 

[big d]

my ogs vary by the weather.as an outdoor brewer when it gets a bit windy the boil drops off so i crank up the gas and then it boils hard so back down we go.then the boil is like a mirror finish.so etc etc.
on good calm days i hit the og spot on.ohh the joys of ag brewing.all fun though.

cheers
big d

 

[GSRman]

doc: last week i undershot by 10 pts on a 1040 beer.. and im an extract brewer...

 

[Doc]

Bugger, GSR. Will end up a lawnmower beer that will only last one mow of the lawns :lol:

Maybe I should add a non-sensical poll. Would you rather undershoot of overshoot OG ?

Doc

 

[sosman]

Well I have just added a sight glass to my kettle to take the guesswork out of how the boil off rate is going.


brewiki brew pot page

 

[GSRman]

doc: it might be nice to have something a bit lighter on tap anyway expecially during summer, and the other tap dispensing 5% stout..

 

[mje1980]

Yeah, i have been having the same problems too. I have been overshooting by about 10 points on my last few batches. I believe its my boil, as i boil the fuggin arse out of my beer, and i boil for 90 mins. I usually batch sparge to 27 litres, and by the time its boiled and cooled, im lucky to scrape in 19 litres. But i like the rough boil as i get the most out of my hops, so next batch, depending on my preboil gravity reading, i will add 2 litres of water at the start of the boil and see what happens. I would rather overshoot simply for the fact that you can water it down and get more good beer, rather than boiling it right down and having less beer. But, when i do my next wheat, i will be only boiling for 45, to keep the colour as light as possible.