Hobgoblin - 28.2.07 (efficiency woes)

[Frothy]

Followed Orfy's recipe, muchos gracias Orfy.
http://jimsbeerkit.co.uk/forum/viewtopic.php?t=2785 (note that there are 3 hop additions and one has been lost in the small print.)
All went without a hitch apart from my efficiency. 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.

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
Aim - 23L @ 1.056

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 ?!? I fly-sparge and my sparging method is to heat 80% of my target volume and pump this on top of the grain bed slowly & maintaining a 1"+ depth of water. I take from 30minutes - 1hr and collect 20-30% more wort than I need to allow for boil reduction. After the sparge water is used up I drain the bed completely. This brew confuses me because I already reduced it down in the boiler by 7L and if I'd added any more wort to the boil I'd have ended up with a similar gravity I guess but a greater volume?

Frothy
5L Jug - a great help
Setup
Brewstand - airlocks fixed
Mess

[monk]

Good job, Frothy. I'm about to try my first Hobgoblin soon. It's sitting in my fridge as we speak. It cost me an arm and a leg at the fancy beer store. If it's good, I'll be following you on the same recipe soon.

Good luck fermenting!

monk

[Andy]

I wonder if you're getting channeling of sparge liquor down the mashtun walls Frothers. That might explain the increase in gravity when you drained down the tun at the end. Try reducing the 1" depth of liquor down to 1cm or less, might increase your mash efficiency also.

[eskimobob]

Agreed, I have actually been experimenting with having a fairly well drained mash bed when fly sparging recently and my efficiency has not significantly changed - I used to just cover the grain with a mm or so.

Only once had a stuck mash and that was only the first few minutes when I started the outflow too fast and consequently sucked the bed down tight.

[maxashton]

How exactly does one remediate a stuck mash? I've heard the term a lot. I read somewhere something abount connecting your HLT to the mash tun to sort of float the grain from below. Is that what you do?

[steve_flack]

If you have a pump then you can underlet liquid into the mash tun from the bottom.

If you don't then you could attach a bit of tubing to the tap and (being very careful not to scald yourself) blow on it.

[maxashton]

Alarming. That sounds horribly dangerous.
Would not manual agitation of the grain be more ... safe?

[steve_flack]

Alarming. That sounds horribly dangerous.
Would not manual agitation of the grain be more ... safe?

That doesn't seem to help much in my experience (having had one stuck mash ever - a 50% Wheat Malt mash).

If you had a long bit of tubing and the end you blew on was above the level of the mash then the blowing technique shouldn't be too life-threatening.

[maxashton]

Good thought. I'm not very on the ball today. 50% wheat eh. Was it tasty in the end?

[mysterio]

I use a good few handfuls of oat husks in my grain bills with a lot of wheat or cereals, seems to do the job.

[Frothy]

She's fermenting away nicely now with some Muntons Gold, 1" krausen.
Ok so channeling. I remember Daab you said when I built my mash tun that the slotted bottom was too close to the walls, but I rectified this already by making it a bit smaller so it comes away from the walls. The slotted bottom sits flush on the bottom of the tun as there is a degree of flexibility in the 22mm - 3/4" coupler. On your advice the only thing I can think of is that my sparge arm only concentrates on the center of the mash (not that this would make much difference with the deep water I've been leaving on top) so plan is to
a) Keep the water level flush with the grain bed
b) Modify the sparge arm (below) into a 2 armed design that gives better coverage.
slotted sparge arm & bottom photo

I just finished another brew & sparged with a more flush water level - bang on 65% which is an improvement

cheers
Frothy

[eskimobob]

Thinking about it from a physics point of view, the sparge delivery method you currently use might actually encourage the liquor to drain down the sides rather than through the grain bed. My thinking is this: You are delivering liquor on the centre line of the mash tun and as it lands, it will tend to flow to the left and right away from the centre line (because more water is landing on top of it) hence you might be setting up a kind of flow across the top of the water covered area towards and down the sides of the tun...

If you were to allow the bed to drain just below the surface of the grain bed then the falling water will have more chance of sinking through the grain rather than running to the sides

Of course, that could be a load of nonsense

[Scooby]

Thinking about it from a physics point of view, the sparge delivery method you currently use might actually encourage the liquor to drain down the sides rather than through the grain bed. My thinking is this: You are delivering liquor on the centre line of the mash tun and as it lands, it will tend to flow to the left and right away from the centre line (because more water is landing on top of it) hence you might be setting up a kind of flow across the top of the water covered area towards and down the sides of the tun...

If you were to allow the bed to drain just below the surface of the grain bed then the falling water will have more chance of sinking through the grain rather than running to the sides

Of course, that could be a load of nonsense

No not nonsense EB but sound thinking, imo what ever method you use to deliver the liquor it is not going to be efficient if you have a 1" plus depth of liquor on top of the grain

[Frothy]

I can see the sense in your theory EB. My efficiency definately went up yesterday with the reduced water level. There's a whole chapter in Palmers on fluid dynamics in mash tuns - very scary!

Frothy

[maxashton]

Not.. fluid dynamics!
*recoils in horror*