Does it hurt to boil the mash down to the right gallons before I start my 60 min time

[Huntervdg]

I am doing a 6 gallon all grain beer and when I finished with my mash tun I had about 7.5 gallons. Is it ok to boil it down before starting first 60 min timer? The sg is a little low also so this should help it.

 

[ram5ey]

No problem.

 

[frazier]

Since you'll be boiling it down for another 60 minutes, your volume will be low.

 

[itsme_timd]

Since you'll be boiling it down for another 60 minutes, your volume will be low.

I assume he's saying to boil it down to the correct pre-boil volume and go from there to hit the correct volume at end of boil.

Is that right OP?

 

[Huntervdg]

How do you calculate the amount of water lost after a 60min boil?

 

[itsme_timd]

How do you calculate the amount of water lost after a 60min boil?

Have you calibrated your system where you know the per hour boil off rate?

 

[Huntervdg]

No how do I do that?

 

[jfk69]

You generally put a know quantity of water into your kettle and boil it for an hour. Cool it and measure the volume that is left. That will give you your approximate boil off per hour. If you want 6 gallons of finished wort into the fermenter, I would guess that 7.5 gallons pre boil will be very close to what you need to finish with 6 gallons. You will probably boil off 1+ gallons per hour depending on the shape of your pot and the vigor of the boil.

 

[Huntervdg]

Ok thanks. I'll have to figure all that out for next time.

 

[itsme_timd]

No how do I do that?

When you brew measure your pre-boil volume and post boil volume. If you've done a 60 minute boil then the difference there is your hourly boil-off rate. You'll want to do this with a few brews to check of consistency and get a good number. Then this can be used as a multiplier for future brews.

Most homebrewers will see rates between 1-2 gal/hr, for example my system is 1.8 gal/hr so if I want to put 5.5 gallons in the fermenter I know I need to have 7.3 gallons pre boil for a 60 minute boil. If I'm doing a 90 minute boil I'd want 8.2 gallons pre boil. (1.8 x 1.5 = 2.7 gal/hr)

 

[jceg316]

Let's say that too much wort was in the boil and you wanted to reduce it, because after 1 hour there's be too much. What effect would boiling have on it? I assume the wort would be more concentrated, meaning a higher OG (as there would be less water) but would there be any other effects?