Hobgoblin - 28.2.07 (efficiency woes)

[tubby_shaw]

and should be avoided at all costs in favour of common sense

Ahh, common sense.
A very wise man once told me
" 90% of problems can be solved using common sense."
He also went on to say
"Unfortunately sense isn't 90% common"
Both very true statements.

[Boo Boo]

You could also try raking the grainbed slightly to reduce channeling.

[SteveD]

Where are you measuring efficiency? Is it in the boiler, or in the fermenter? Are you losing a significant ammount as ullage in pumps, pipes, bottoms of vessels? I ask because there's got to be something majorly wrong to be losing it all in the mashtun as poor extraction. I flood mine, float it off, drain, it completely sometimes, balance the outflow, switch from batch sparging to fly sparging and back again all at a whim, and often all within the same mash! It all depends how bored I'm getting. Sparge liquor temperatures range from 75c to boiling - I monitor the mash bed temperature and keep it between 70 and 77c. Yet through all this abuse I manage to get good efficiency - very good, if I concentrate on getting every last bit of extract. I use brewhouse efficiency as a measure, ie volume & gravity in the fermenter.

One question...how fast are you running off? Despite all the abuse I put the mash through, I make sure the run off rate is not too fast. The sparge liquor needs time to dissolve the sugars, so if you've got the liquor rushing through you'll end up with a full boiler having left half the sugar behind. It usually takes me an hour or more to collect 7.5 gallons of wort using a coolbox mashtun, slotted manifold and a spinny sparger. Before I started using more malt and deliberately stopping before the 1006 figure was reached I averaged 90% brewhouse efficiency. Tonight I got OG 1047 in 25.25L in the fermenter - but from 4.5kg grain - about 87% efficient - a bit too much! Old habits die hard.

When you drain down at the end, is that after it has stood a little while? If that's the case, then it may be that you're not giving the liquor enough time to pick up the sugars and/or it's channelling down the sides.

Also you could try collecting a bit more, and boiling a bit harder, monitoring the runnings to make sure they don't fall below G1006

[Frothy]

Steve
I take from 1/2hr - 1hr with my sparge & I drain down the tun at the end. With all my efforts I do wonder if my calc's are to blame as I do them by hand and I'm currently taking pale malt & flaked barley etc. to be 300 P/Kg/L & crystal Malt to be 240 P/kg/L. For measurements I take the gravity of the final volume in the fermenter after I have topped up to meet the target volume. I sparge to collect ~ 30% extra to allow for boil reduction.

Infact I just tried adjusting my calc's to tried and tested imperial measures & same results if anything my efficiency got a bit worse, so it's not the calc's.

???
Frothy

[eskimobob]

Have you got your recipe handy Frothy and we can run through it to see if our calcs agree with yours...

[Frothy]

I increased the grain bill to account for my typical 65% efficiency & adjusted the hops for the different AA although the latter probably wasn't worth it.

Aim - 23L @ 1.056
65%
5.53kg Marris Otter
0.29kg crystal Malt
0.23kg CaraPils Malt
0.17kg Chocolate Malt

Strike temp' - 69oc pH 5.45 (Spot On)
2.5L/kg
Local Water - 94mg/L Calcium (in the target 50-150)
Mash - 90minutes
Final Temp - 64oc


Sparge - 79oc 22L (80% of target vol')
Collected/ Boil start Vol' - 30L
Result - 23L @ 1.048

I collected a further 1.5L of wort after 30L and it was very thin although I measured it after the event and it measures 1.046 ?!?

Your channeling theory looks stronger than ever EB
Frothy

[eskimobob]

Sorry Frothy, didn't scroll up to see you recipe on the first page.

Well, plugging the recipe figures into Brewsmith says that for 65% you should get an OG of 1052. Therefore your 1048 is not quite as far out as you thought - still a bit lower than it ought to be though.

I don't quite understand the bit you put about collecting 1.5 litres and after 30 litres and still getting 1046. It sounds as if you are definitely getting some channeling so that there is far too much sugar left in the grain - by the time you reach 30 litres it should surely be a lot lower than that

[SteveD]

Steve
I take from 1/2hr - 1hr with my sparge & I drain down the tun at the end. With all my efforts I do wonder if my calc's are to blame as I do them by hand and I'm currently taking pale malt & flaked barley etc. to be 300 P/Kg/L & crystal Malt to be 240 P/kg/L. For measurements I take the gravity of the final volume in the fermenter after I have topped up to meet the target volume. I sparge to collect ~ 30% extra to allow for boil reduction.

Infact I just tried adjusting my calc's to tried and tested imperial measures & same results if anything my efficiency got a bit worse, so it's not the calc's.

???
Frothy

Right... first I don't think Flaked barley gives you 300. Wheeler rates it at 253, and crystal at 268.

Secondly you calculate brewhouse efficiency, as I do, so look for losses to hops and ullage between boiler and fermenter. There's nothing wrong with doing calcs by hand, as long as the calc are right!

I use Wheeler's from his first book.

Efficiency = (OG x Vol) / (Ext x Wgt)

OG is last two digits only, so for 1044, put 44 in the calc. The OG can be preboil, or in the fermenter before or after top up - as long as you use the corresponding volume figure!
Vol is Litres
Ext is the lab extract figure for the grain
Wgt is that of the grain in KG's

You add the ext x wgt figures for each grain you use in order to put one figure into the calc.

Thirdly, if you're getting noticeable sweetness in the runnings after 30L, it's likely you're channelling down the sides. There shouldn't be much left by then. Or, if there's a lot of capacity below the level of the mashtun take off, the sweeter and therefore heavier cooler wort could pool there - back to ullage

[Frothy]

Muchos gracias guys.
Looks like next brew I'll take into account my losses in the system & some new figures thanks steve, my calc's are fine otherwise. It is true that I probably loose a litre or so in the pipework & a little bit to the hops. The high gravity final runnings as you say certainly point towards some kind of channeling/ dead spot in the tun during lautering. During this mash I had an exceptional amount of water on top of the grain bed whereas the brew I made the next day I reduced this volume to little/ none on top of the grain bed & achieved dead on 65%. Still room for improvement, a sparge arm that gives more coverage and possibly increasing the temp of my sparge water to 80oc or so. Will let you know next brew. It's a game isn't it

cheers
Frothy

[SteveD]

a sparge arm that gives more coverage and possibly increasing the temp of my sparge water to 80oc or so. Will let you know next brew. It's a game isn't it

cheers
Frothy

That would help, as better coverage would give you the option to not have to flood the mash in order to reach every part, and would mean you could trickle the liquor through the bed rather than have it channel down the sides. Also, watch your run off speed, 30 mins is a bit quick for 30L. Give the sparge liquor time to dissolve the sugars. One thing you could do, if you've got a free running mash is periodically stop sparging and drain the bed, to get all the good stuff out. Give the tun a tilt if it gets you the stuff in the dead space. Then start up the sparge to refill. It's sort of a semi-batch sparge in the middle of a normal fly sparge, which I'll do every now and again.

On sparge liquor temperature.....My set up has the HLT feed the phil's sparge arm via a 2' (60cm) length of 3/8 plastic pipe contained within pipe lagging. The mashtun is a standard coolbox. In order to maintain a mash bed temperature near the ideal of 77c, or say, in the range 70-77c, my HLT temperature has to be between 90c and boiling. Until I started monitoring mash bed temperature I never realised so much heat was lost, and that simply following 'book' wisdom and sparging with liquor at 77c was giving a mash bed no hotter than about 60c. Food for thought.

It's a game all right, where the rules change every five minutes!

[louthepoo]

what's a HLT?

[Frothy]

In order to maintain a mash bed temperature near the ideal of 77c, or say, in the range 70-77c, my HLT temperature has to be between 90c and boiling.

Excellent point, the juice I've been running off has been ~ 55-60oc which could explain alot. Your suggestion makes me think that I could
a) Decoct the mash at the end to raise it to 80oc
b) Infuse the mash with boiling water to raise it to 80oc
c) HERMS

This is a benefit of the HERMS system I never would have considered. I've had all the bits to do it for a while but since infusion mashes have been a bit troublesome I've put it off.

Frothy

[SteveD]

In order to maintain a mash bed temperature near the ideal of 77c, or say, in the range 70-77c, my HLT temperature has to be between 90c and boiling.

Excellent point, the juice I've been running off has been ~ 55-60oc which could explain alot. Your suggestion makes me think that I could
a) Decoct the mash at the end to raise it to 80oc
b) Infuse the mash with boiling water to raise it to 80oc
c) HERMS

This is a benefit of the HERMS system I never would have considered.

Frothy

.....or have your hot liquor tank at 90c to boiling so the sparge maintains the bed at the right temp. I've been thinking about HERMS (heat exchange recirculating mash system - for Louthepoo ) as well. Initially, not so much for general maintenace of mash temperature, but for the ability to change the temperature, and to clarify the wort.

The way I mash now is in an insulated unheated coolbox. At the end of mashing I recirculate a jug or two of wort to get it to run clear-ish or at least free of grainy bits - this does two things they don't write about, in addition to the things they do - jugging wort back on top of the mash is a good way to oxygenate it exactly when you don't want to, and, it cools the bed down - when you don't want to. With HERMS I'd start the recirculation with view to raising the mash bed to 77c, before sparging, and the clarification will happen as a matter of course.

Then I saw Seveneer's HERMS working and it maintains a rock steady mash temperature, so I thought why not go the whole hog and use HERMS properly.

One thing to watch is to not let the mash temp rise above about 77c otherwise you're risking extraction of phenols, etc.

[louthepoo]

I've been thinking about HERMS (heat exchange recirculating mash system - for Louthepoo )

Thanks steve - i didnt have a clue what it meant, still new to the technical side of things, like being at school!!

[Frothy]

I think HERMS is certainly more efficient for larger brews what with small losses in the pipe-work etc. I'll go down that route once I've got a bigger mash tun.

After a few infusion calcs. For a 5kg batch @ 2.5L/ kg if my mash was at 60oc and I wanted to raise it to 80oc this would take approximately 14.5L of boiling water. Worth a go? Like you said it's mixing a matching a bit of batch/ fly sparging technique. I'm slightly concerned about the heat distribution causing spots over 80oc as you say but won't know till I try.

Frothy