Hitting OG before boil

[liammiller]

I am fairly new to brewing and have not managed to dial in my efficiency, boil off volume, grain absorbtion etc. and therefore there is a level of uncertainty when it comes to my post-boil volume and OG. This is the plan that will allow me to avoid measuring the volume of my wort after boiling:

1. Test gravity of wort before boil add either water (if gravity is high) or DME (if gravity is low) to hit target OG before boiling.

2. Note volume of wort in kettle before boil.

3. After boil, top up with water to return wort to pre-boil volume and OG.

This might be a terrible idea for reasons that I have not thought of but I think I might have a solution to my problem and wondered if anyone might have anything to say about it or any problems that this might cause.

 

[suffolkbeer]

All sounds rather complicated.

1) build recipe on brewers friend or similar (it will give you exp pre boil SG and exp OG and exp FG)
2) boil wort then measure OG
3) ferment
4) measure FG

 

[liammiller]

My concern is that I will measure gravity post boil and it isn't where I want it. I suppose my question really was if I replace the water lost during the boil will I be left with the same gravity as before the boil and are there any problems that might come up from doing this?

 

[Ghillie]

You're right @liammiller - it is a terrible idea...

I've read through your post about half a dozen times now and I still don't understand what you're saying or asking.

-If you don't know your efficiency; it doesn't matter. There's only one way to find out - brew a beer (by whatever means you're going to use)! You can work out your mash efficiency from calculators available free online.

-Forget about grain absorption altogether; it's completely negligible with small scale home brewing. Simply mash and sparge until you reach your OG and/or pre-boil volume (whichever you prefer). If you want a specific ABV% then sparge until you hit your OG; if you want a specific amount of bottles, then sparge until you reach a desired volume. Once you've done this a few times and worked out your mash efficiency; then you can then meet both OG and pre-boil volume.

Boil off volume is the easiest to work out. Brew a beer and work out the difference. You'll usually loose somewhere between 3-5L per hour.

Don't get tied up with numbers if you're just starting out. Remember you're making beer and the important thing is that it tastes nice. I bet there are plenty folk out there who get so hung up on numbers that their beer ends up tasting like ***** :)

 

[IainM]

While there is nothing technically wrong with what you want to do, why not have a stab at your boil off rate and adjust your post-boil gravity if it is wildly off the mark? At least that way your total pre-boil wort is larger given your target final gravity and volume, so your efficiency will be higher. After all, what you are trying to dial in is a process without need for adjustments. If you aren't far off, who cares? Enjoy the beer as it is and adjust your numbers for next time.

 

[Fil]

to aid measuring your boil volume easily, employ a dipstick, currently as my boil kettle is a 50cm diameter pot i get away with a SS ruler 0.5cm = 1l but in my old 5 gallon system i used a ss racking cane with a cabletie tightly atached at the level of 5 gallons in my kettle.

this gives you a ready reckoner you can use on the fly to gauge how your boil is progressing towards your boil target.
And if using the usual diy 2 x kettle element bucket boiler you have rough power control by switching on and off the second element so if your not boiling off enough you can perhaps boost the boil for 20 minutes??

But Dont worry too much if you boil off too much as your learning your system as you can simply liquor back (water down) the wort with some left over sparge liquor at the end of the boil.

But you needent really worry too much. Big deal if you brew short or long and your targets are a bit off, as long as you end up with more than 3.2% abv the beer will have shelf live And you will relish every drop regardless of strength..

More importantly you will have crucial data about your setup, the boil off rate you can expect.. with this you can refine your liquor requierments and home in closer to hitting targets next brew..

PS dont rely on volume markings on buckets etc, they are for illustration purposes and can be wide, eventually you will need to sit down and weigh 1kg of water in a jug and measure out litre by litre the volumes of your brew vessels

have fun.. and dont worry even though it may appear a bit daunting atm, you are so close to it all just falling into place..

And regardless of what calamities or errors occur on a brewday, carry on, the beer gods smile down on determined brewers and new brewers too and can be surprisingly forgiving ....

 

[Zephyr259]

What type of system are you using? Personally, I'd brew something simple (but tasty) assume a boil-off rate, like Iain suggests, then see what you lose to evaporation. If you are brewing a full 5 gal batch then the difference between 3 and 5 litres will be negligible. My first AG brew was a 1 gal batch and I just boiled and was happy with what I ended up with, which turned out to be a 6.4% bitter due to higher boil-off than expected.

The bit I find important in brewing is taking (and keeping) good notes with gravity readings and volumes at all stages, so pre-boil sg and volume (which lets you calc mash efficiency) then post boil sg and vol, finally fermenter volume which should have the same sg as post boil, gives you your brewhouse efficiency and lets you see what your kettle dead volume is.

When calculating expected pre-boil sg from the target OG you need to compare pre-boil and post-boil volumes rather than final fermenter volume. Sounds a bit tricky but it's not so bad and to be honest I still don't make adjustments, I record my pre-boil data to compare but I'm generally either close enough or slightly under gravity and don't keep enough malt extract to hand to adjust and would rather hit my volume at a slightly lower abv than boil longer to hit the target.

Hope this helps.

 

[Oneiroi]

I’ve topped off the odd litre or so post boil if I ended up a bit short but not sure I’d want to be adding 25% of my volume back in. From my limited understanding, issues around hop utilisation and diluting the flavour compounds from hopping would be the biggest issue, so you may need to up the hops to balance it out.

I would just do what others have suggested though, go with it, make some beer and experiment and then adjust your process as you learn more about your set-up


Sent from my iPhone using Tapatalk

 

[Martybhoy]

Brew a beer and use your own data for working out future beers. It might take several brews to get to solid figures but you'll still be making good beer.

For a rough idea, my grain absorption is almost always 1lt of water per kilo of grain. My boil off rate just under 4ltrs per hour. And my gravity will rise 8-9 points per hour of boiling.

 

[Cwrw666]

Brew the beer. If your volume is below target add some water. Check OG. If it's a bit low add some sugar / DME to get it right. If it's a bit high, enjoy.