Digiboil, Final vols and chilling

[Drubbing]

I've been brewing about 6 years, Started with kits, then hop additions and grain steeps to these. I did partial 4kg extracts in a big pot before getting the digiboil recently and I'm doing BIAB. But two brews in, the Digi is not delivering the final volumes from recipes.

My last brew went well. I nailed the mash temp on strike and held it for the 60min mash. I sparged the bag until I got the 28l pre boil, as per the recipe I'm following. Then 60min boil. It wasn't even a fierce boil, as I had the smallest element off. I got 21L post boil, not 23. But my OG was bang on, as per recipe. Any ideas?

A second question is chilling. I'm not getting a coil chiller. I got 3 kids and my water bills are already heartstoppers and it's more work. I tried an ice bath before but it was PITA, so got a hot cube from the brew store - food grade HDPE etc. First, the bung leaked and had to tighten and gaffa tape it. Then the thread stuffed up with the heat and wouldn't seal tight.

I've seen quite a few vids where Aus brewers have just clingfilm the digiboil, then clamped the lid and left overnight. I'm aware the science-based brewers won't hear of this, but I've not found any reports of infection this way. Anyone tried this?

 

[golfandbrew]

It's not the digi's fault. You have already made some good observations now just adjust your equipment profile to get you inline with the recipe.

 

[MHB]

I'm one of those science-based brewer types. Happy to tell you that there would be very little risk of infection.

Sadly that isn’t why anyone who knows anything about brewing is going to tell you it’s not a good idea.
You will make better beer if you get the wort off the hot break and other trub as soon after the boil finishes. I and lot of other brewers use no-chill and are more than happy with the process. It's unusual to have a cube fail that quickly, some are good for dozens of brews.
It might be worth getting another cube (from a different supplier) and try again. Lots of people just use recycled fresh wort kit cubes.

From what you posted above I suspect there some other problems with your equipment/process or how you are measuring stuff. Your boil off is close to 18%/hour, 10 would be ideal.
It also sounds like you left some extract in the grist. Fast sparging and poor milling are what would come to mind first.
If you are interested in posting some detail on what you put into the brew, we might be able to help improve your yield.
Mark

 

[elmoMakesBeer]

You ended up with 21 litres post-boil at your target gravity. Well done and enjoy your beer.

To respond to your first question on boil-off rate, which digiboil are you using? I use the 35 l one (2400 w) as a kettle in a 3v setup, and get 3-4 l/h boiloff. If you have the 65 l (3500 w) version, running at 3000 w with 28 l preboil I could imagine 7 l/h boiloff would be about right. Try dropping it to 2000 w or 2500 w next time once you reach boiling point. If you use the smaller version are you actually boiling over (very easy to do) and losing wort that way?

If you’re looking for better efficiency there could be plenty of possible areas to examine. Is your grind too coarse? With biab you should be able to get away with finer than those recirculating. Uneven mash temp? If you’re heating from the bottom and not stirring the top of the mash might be quite a bit cooler than the bottom, where the temp sensor is. Or just accept you’re getting poorer efficiency than the recipes you’re using indicate and add an extra 10% of grain.

I’m a fan of hot cubes. I have a chiller coil but hot cubing is easier, saves water, and means I can start the ferment another day when it suits me. I had a lid that didn’t seal properly once but I fermented it the next day when cool and it turned out fine. I’ve never tried cling wrap on the digiboil. It probably works but as Mark pointed out above it’s best to get your nice wort away from the hot break.

 

[Drubbing]

You ended up with 21 litres post-boil at your target gravity. Well done and enjoy your beer.

To respond to your first question on boil-off rate, which digiboil are you using? I use the 35 l one (2400 w)

If you’re looking for better efficiency there could be plenty of possible areas to examine. Is your grind too coarse?

Thanks for the reply.

I've got the same. My boil was only using the 1900w element. With both on, it boils hard.

I buy pre milled grain bills from my brew shop. However, bills for my 2 brews came from different suppliers and both came up short after boil. With the first one, the OG/FG numbers were also way off, but the ABV came out as per recipe. It's a good American Cascade pale. So I know decent beer can be made without hitting recipe numbers.

My second a Scottish ale, was a textbook brew. Mash temps perfect and held for 60min. The OG spot on as per recipe, just 2L less yield. I'm aware of the temp variance because of the sensor location. I added a jacket for this brew and manually recirculate every 15 min. Adding 10% grain may be worth a go.

I like the idea of hot cubing for water saving and convenience, my experience was not good though.

I'm one of those science-based brewer types. Happy to tell you that there would be very little risk of infection.

From what you posted above I suspect there some other problems with your equipment/process or how you are measuring stuff. Your boil off is close to 18%/hour, 10 would be ideal.
It also sounds like you left some extract in the grist. Fast sparging and poor milling are what would come to mind first.

Thanks Mark

I'm not measuring anything myself, I'm buying milled grain bills, and following recipes. 19l strike water, mash, then sparge to 28l. I boil 60m as per the recipes I've chosen, and ignore the digi markings on the wall, as rolling boils are not reliable for measuring.

I have no boiling sparge water, it's just a hot water sparge through the bag and i squeeze it regularly. But this means I'm waiting half hour or more to get the digi boiling up with a full load. Perhaps this is a factor.

 

[Coalminer]

I would suggest getting cubes that are "Dangerous goods" quality
The bung hole is blank and is not punched out so no thread issues
I have cubed 260 brews so far without a leak or infection using these cubes

 

[Half-baked]

Agree it’s important to get a bung-less cube.

Have you tried a full volume mash (or close to full vol)? If you don’t have the means to do a proper sparge (it’s hard to when using a bag) this will help your efficiency a lot.

That’s what I usually do when using my digiboil, that way sparging is less important.

This is how I approach a full-ish vol mash in the digiboil…

20l cubes take around 22.5l (cool, so 23.5 hot), so I aim for 25l final vol. As said above, boil-off should be around 4l/hr, so that’s a boil vol of 29l.

With a 5kg grain bill it has displacement of around 4l and absorption of 5l. So the grains take 9l.

That’s 34l of water and 38l of total volume in a 35l system.

Fill the digi with 33l of tap water (factoring in expansion), bag already in, heat to strike, draw off 5l (I use a 5l cooler jug) then mash in. Should be full but not overflowing.

Mash however long you need to, if you can recirculate then that will help a lot. Mash out, again recirculating if possible.

Pull out the bag, into a food safe bucket then pour over the sparge water. Remove the bag and squeeze if you want, then put the remaining liquid into the kettle.

Sparging at this point shouldn’t make a huge difference to overall efficiency as you should have already extracted most of the sugars. But it all helps.

A mash with 29l will give you much better efficiency than with 19l. And it won’t hurt the flavour (I’ve won categories in competitions using a very similar method)

 

[Drubbing]

Have you tried a full volume mash (or close to full vol)? If you don’t have the means to do a proper sparge (it’s hard to when using a bag) this will help your efficiency a lot.

Thanks for this. I thought a full vol mash was as per the recipes I've been using so far - usually 19l, then sparged to 28l before boil.

If a 29l mash is more efficient and avoids a big sparge, I'll give it a go. Bag sparging is a pain and messy. I'll probably get the malt pipe upgrade at some point.

 

[Drubbing]

A mash with 29l will give you much better efficiency than with 19l. And it won’t hurt the flavour (I’ve won categories in competitions using a very similar method)

Gave this a go with an ESB recipe. Thought 29l might be a bit large, so went 27. Everything went well, had to fiddle with the temp to get it settled, as I found the strike temp needs to be closer to mash temp with the extra water in there. I found it easier to hold the temp with the extra water though.

Ended up with 22l plus hop matter, so pretty good. OG spot on as per recipe.