Philip321 wrote:HELLO Contrarian,
You've hit the nail right on the head.
Fortunately I started with a new 25 Kilo bag of Marris otter so I weighed it and I have only used 5.1Kg. I should have used 6.899kg
No wonder the gravity is only 1.034....
That's great you have found the problem Philip
.
Incorrect weighing is the most common reason for actual kettle efficiency being lower than the estimated and it's very easy to do.
Here is a checklist of this and other reasons that can cause low efficiency.
Because it is so easy to make an error in weighing, I always employ a double check. In other words, I'll weigh the grains individually but, then I'll also weigh the total grain bill. (Basically, you need to know the weight of your bucket or whatever you are pouring your individual weighed grains into.
I also try to employ double-checks on kettle efficiency (volume and gravity) readings as, strange though it seems, occasionally, you just get weird readings. (I see that in that checklist, I didn't mention "hydrometer jar too narrow" or "wort not mixed well before taking gravity sample," which are other easy errors to make.
A good mantra is, "Never trust a single reading on a single brew." (Mind you, that advice doesn't go down too well sometimes - see
this and the subsequent post
). You've got a few brews under your belt from memory so when you get a sudden "kettle efficiency" shock as you have on this brew, if you don't have the double-check on weighing grains up your sleeve, you can be confident the problem was with that or an unreliable gravity sample.
...
One other thing I want to expand on that has already been mentioned above is your strike temperature. Check out the second line of Section E. It says strike at 66.6C to achieve your mash temp of 66C. Striking at 70C is definitely too high. In fact, if you waited until your water reached 70C and then immediately mashed in, you'll have an even bigger problem. Here's why...
Large/Heavy Kettle Set-Ups Continue to Heat even after Flame is Turned Off
I have gas-fired 70L kettles. Let's say I wanted my strike temp to be 67C. If I turn the flame off as soon as it gets to 67C, if I let it rest, then agitate the water, it will be at around 69C. So, I must stop it a bit below the temp I want, and let it rest for 5 mins before striking.
Applying heat during the mash on these heavy set-ups has similiar problems. Let's say I am mashing at 66C and then 30 mins into the mash I notice it has dropped to 64C. Once again, if I agitated and applied heat until it returned to 66C, after five minutes of me having the flame off, I'll see it has jumped to 68C. You'll notice it takes ages to go from 64 to 65 but then things accelerate rapidly (because, that first period of time was spent on heating your kettle stand and kettle up).
Basically, always err on the low side of things and definitely let your kettle settle down for five minutes before striking.
As mentioned, my kettles are 70L while yours is 100L. This means the problem above will be more pronounced with yours especially if brewing small batches in the large kettle.
...
Please let us know how the beer tastes though. These "errors" can teach us all a lot. For example, your high mash temp could well give you a very well-balanced low alcohol beer. It's quite possible you'll find the end result a great drop.
PP
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