I'm still doing something wrong..

[bigdave]

Brewed AG4 today and I'm still struggling with my setup but I don't know where the problem is.

Over recent brews my mash efficiency has been around 68% but having allowed for that, today it was 75%

I've had major issues with hop stoppers blocking, but today my new SS braid worked pretty well although I was left with 3(ish) litres in the boiler once it had stopped draining

I'm down to 1/4 tsp protofloc.

My water's harder than Gary Glitter at Disney Land.

Thing is, working on a 75% mash efficiency I've hit the nail smack on the head today.... but only collected 15ltrs!?

I'm all but done in by trying to work out what the fnuk's going wrong!!

[guypettigrew]

How do you mean "working on a 75% mash efficiency I've hit the nail smack on the head today.... but only collected 15ltrs!?"

Can you give us your grain bill, your mash and sparge liquor volumes, your pre and post boil volumes, please?

Thanks.

Guy

[Martin G]

Here are some questions that come to my mind, not sure if they help or if you have already thought of them.

Is it 3l as well as the hop absorption?
Is the problem with draining from the boiler preventing you from syphoning out the last bit?
Assuming you have pipe on the outlet tap of the boiler, does it drop about 50cms before it pours out into the fermenter and is it narrow enough, at least at the end to keep the syphon going?
I guess even with 3l you'd still be at 18l and presume you are after something like 23l, when you say you hit the nail on the head is that the OG? It would seem odd that the efficiency is higher than expected but you hit the target OG and had a smaller volume. Something doesn't seem to add up, if efficiency is higher than expected and volume less than expected then you'd think the OG would be higher than expected.

[ivanmalley]

Recording pre boil and post boil volumes and gravities will help you keep track of where the problem lies.

For example if your pre boil volume and gravity are correct but you end up with less than expected but at higher gravity you are boiling off too much liquid.

[bigdave]

Apologies, I'd posted from my phone whilst attempting to convince my 4year old to go to sleep!! lol

My previous recipes have been based on a 75% mash efficiency but after some investigation I'd realised that my efficiency was actually 68% (causing a significant drop in pre boil gravity).... So.... today I set out on another SMaSH (5kg MO, 100g Rakau) having calculated everything based around my 68% efficiency.

According to BeerAlchemy I required 25ltr pre-boil to hit my 20 ltr post boil target (allowing 2.25ltr for trub, hops etc) so mashed accordingly (mash in 12.5ltr, mash out 5ltr, collect 12.5ltr, batch sparge 12.5ltr, collect 12.5 ltr)..... I've just checked BA and I'm not sure that figure includes evaporation?...

But anyway..

working to a 68% mash efficiency I was expecting 20ltr post boil:
Pre Boil @ 20º 1.042
Post boil @ 20º 1.047

I achieved 75% mash efficiency but only collected 15 ltr post boil:
Pre boil @ 20º 1.048
Post Boil @ 20º1.052.

[bigdave]

*EDIT*

Maybe I'm relying too much on computers and not enough on the maths?!?..

[Martin G]

*EDIT*

Maybe I'm relying too much on computers and not enough on the maths?!?..

I know what you mean, whatever the maths, you just need to add a few more litres of water somewhere and it will fall about right!

[jmc]

Pre-boil volume seems low for target 20L in FV

If 25L pre boil & 10% evaporation per hour & 90 min boil
vol post-boil = 25 x 85% = 21.25

Assume you cool before pouring off
Shrink @ 4%
21.25 x 96% = 20.4

If you had target hop/trub loss of 2.25L then
expected vol in FV = 20.4 - 2.25 =18.15L

Maybe your evaporation rate was higher and trub loss greater to give you the 15L?

Did you record your post-boil volume?

[bigdave]

On my last brew I recorded the evaporation rate at 12% so just used this as the figure to work from. (60 min boil).

When I poured the trub, hops etc away, I'd say there was maybe 3-4ltr still in the boiler. Something that has been running through my mind is that I never used to use protafloc on my old set up, just plain old irish moss and never had a problem with the amount of wort I collected, so maybe I should ditch the protafloc and do the maths the old fashioned way for the next brew to see how I get on?

[jmc]

Recalculation using your new info.

If 25L pre boil & 12% evaporation per hour & 60 min boil then hot
vol post-boil = 25 x 88% = 22L

Assume you cool before pouring off
Shrink @ 4%
22x 96% = 21.1

If you had target hop/trub loss of 4L then
expected vol in FV = 21.1-4 = 17.1L

Still doesnt explain 15L in FV?

[bigdave]

I think hop loss would be on top of that so 16l collected is probably not too far off.

[Kev888]

working to a 68% mash efficiency I was expecting 20ltr post boil:
Pre Boil @ 20º 1.042
Post boil @ 20º 1.047

I achieved 75% mash efficiency but only collected 15 ltr post boil:
Pre boil @ 20º 1.048
Post Boil @ 20º1.052.

The 'expectations' seem correct to me, Dave, but not sure about the calculation for the efficiency in the 'actually achieved' figures - 5kg of pale malt resulting in 1.052 @ 15L (or guessing the pre-boil volume) 1.048 at 17L perhaps sounds more like the low-to-mid 50s rather than 75%?

If so then it looks like your issues are at the mash/sparge stage, and so perhaps you may be over-complicating things by bringing in later factors as well. The evaporation does not (noticably) affect efficiency - its mostly just water you're losing; you've still got more or less the same amount of extracted sugars in there pre and post boil. The later losses to hops and deadspace also aren't attributable to mash efficiency either, though of course they do reduce brewhouse or overall efficiency. So these could be clouding the calculations?

Cheers
Kev

[bigdave]

Mash efficiency was calculated based purely on the pre boil gravity using an online app (no idea which one).

Id be quite happy with an efficiency of 10% if I know that's what I'm going to get and can collect 20ltrs post boil because its a point to work from. At the moment there seem to be so many possible [censored] ups the whole thing's getting irritating.

For example, I estimate a 2ltr dead space in the boiler & I use 100g hops so that's 3ltrs lost. I know my kit evaporates at a rate of 12% per hour so to collect 20ltrs I need to boil 26 ltrs. On this brew I didn't allow the 1ltr for hops (Whoopsy) so boiled 25 ltrs yet somehow I only collect 15ltrs?!?

Working back, there's the 1ltr for hops (that makes 16ltrs) then possibly 2 extra litres on top of the dead space once the hop stopper had clogged so that's only 18 ltrs.

[Kev888]

If its of use, this is an example of how I calculate my volumes:

# End volume wanted in keg = 19L
# Say FV deadspace is 'for example' 2L, so I would need 19+2L = 21L in the FV before racking
# Say Boiler dead-space is also 2L, I would need 2+ 21L = 23L in the boiler
# 100g of whole hops will retain about (roughly) 1.5L (or more if you can't drain very slowly at the end) - however if the hops are in the existing deadspace they don't create extra losses, only if they retain liquid 'in addition' to the deadspace. Say they do in my setup: so the total needed is now 1.5L + 23L = 24.5L
# Say I lose 12% to evaporation per hour of boiling and boil for 1.5 hrs, so then I'll need to start with (roughly) 12% x 1.5 = 18% more; 118% of 24.5L = about 29L at the start of boil
# Say the MT has a dead space of 2L, and also 5kg of grain will retain about 5L, so I need to push a total of 29+2+5=36L through the Mash Tun
(if you wanted to mash at 2.5L/kg that would comprise 12.5L for the mash and 23.5L for the sparge)
# Say the HLT has a dead space of 1.5L, that would be a starting volume of around 37.5L

All very rough rules of thumb for losses to hops and grains, and very setup/deadspace dependent, but it gives the idea - as you go to smaller batches small amounts make bigger differences and fixed dead-spaces become more inefficient so the estimates get rougher.

However, this is just about volumes and losses; they don't affect mash efficiency (just overall/brewhouse efficiency) and I'm concerned that you also have a problem with the mash/sparge - i.e. what you extract from the grain. I'm normally the first to say mash efficiency isn't the main aim, but if (as it seems) you got around 55% then something is wrong in addition to any volume losses - wrong enough that its unlikely to be predictable.

Its difficult to say where though - could be anything from the tun or filter design to temperatures to sparge technique etc. Although it could also be partly measurement error - it may be my incompetence but I have a lot of trouble measuring the gravity of the wort collected in the boiler, because the gravity is much lower towards the top and takes a surprising amount of stirring to make it even out.

Just making suggestions really, in case any light a bulb..

Cheers
Kev

[bigdave]

As I see it these are possible causes for my persistent balls ups...

Mashing:
• Uber hard water
• Cheap thermometer
• Mash tun leaks

Boiling:
• Hop stopper always blocks at some point regardless of design and speed of draining making it impossible to gauge exact losses

Possible solutions:
• Stop using protafloc and see if that improves boiler drainage.
• Buy Salifert kit and treat water.
• Buy decent thermometer.
• take mash tun to bits to try and stop leak.

How does that sound?