Look into minimizing losses to dead space in the mash tun and kettle.

What is your typical OG? The higher the OG, the more grain you are using, hence lower efficiency due to grain absorption.

There is actually a minor bug in the conversion efficiency calculator that is under-reporting in most cases. We are working on fixing that by Monday morning. Brewhouse will still be the same though.

 

This question has been bugging me a bit too.
My efficiency is a consistent 62%, even though I sparge directly into the boiling pot, and my mash-tun only has about 1l. of dead-space (my total mash volume is generally just short of 30l.).
In my case, I think there are two factors hindering me from getting a higher brewhouse efficiency:
1) my boil-off is quite low. The pot is IMO a bit too small, and on an electric stove the boil is hardly "aggressive". I generally only hit about a 15% boil off with an hour boil.
2) I buy all my malt pre-milled, and I have the feeling it might be milled a bit on the course side. The good thing is, I haven't had any stuck sprages, but think it may be affecting the efficiency a bit.

 

Grain crush is very important.
I have the mill in the store set to .038 and it gives a great crush. I typically get 75% with normal process.
Another big factor is your sparge and collection method.
Zel said he's sparging over 60+ minutes, which is a good amount for a fly sparging, but what type of manifold or false bottom do you have?
I'd try a double batch sparge time and see if your efficiency goes up. If it does, then you're channeling during your sparge and losing efficiency.
There is a section in JP's How to Brew that goes over manifold design and fluid mechanics that is very helpful in mash tun design. It's in the back around page I think. Here's a link http://www.howtobrew.com/appendices/appendixD-2.html

If you need help with a design, call me at the store and I'll see if I can help.
Brian

 

If I understand the terminology correctly, brewhouse efficiency includes all the volume losses before the wort hits the fermenter. If I take all of this into account, I'm probably working at a 70 - 71% brew house efficiency - with a 90% mash efficiency.

The only major difference that stands out for me between the process you describe and what I do is the length of time you spend sparging. What method are you using to sparge out? A sparge for me typically takes about 15 minutes and consists of me gently pouring about a litre of near-boiling water on top of the grain bed every minute or so.

In my (limited) experience there are few other factors to consider;

1. Water-to-grain ratio. The standard is 1.25qt/lb (in metric 3.1 ltr/kg), but I try and shoot for a thinner mash at 1.8qt/lb (4.5ltr/kg). People say this has a positive effect on conversion efficiency and my personal experiences would tend to back that up. Also has the positive effect of minimising mash tun dead space and heat loss.

2. Is your mash tun lid insulated or just hollow plastic? If hollow, drill a hole at each end and fill with builders' foam.

3. Unmalted adjuncts. I think the highest mash efficiency I've ever had was due to the using a good proportion of flaked barley. Being unmalted it contains a higher concentration of starch than pale malt but no enzymes. The enzymes from the rest of the grain bill have the capability to convert those extra starches from the flaked barley into sugar.

4. Use a hop sock. This makes the process of siphoning from the kettle to the fermenter much easier and minimises kettle losses. The biggest loss for me in terms of brewhouse efficiency is probably the deadspace at the bottom of the kettle thats full of protein gunk. I'm instantly writing off about 4 or 5 litres by leaving that in the bottom of the kettle and not transferring it across. Having a whole load of spent hop flowers or pellet residue down there too is only going to increase that loss.

 

pH of the Mash, mash time, and mash temp are factors in conversion efficiency. Start tracking that in your brew sessions by entering a Mash Complete log entry. I'm at 90% on a bad day (it was cold in the shed yesterday), but I can hit 100% on my thin walled coleman cooler as well - involves stirring well, and doing a 90 minute mash.

After conversion efficiency (which can be at 100 with some practice), all other efficiency losses are due to volume losses:
Grain absorption - not much we can do about this, and this is most of the issue - bigger grain bills have lower efficiency
Mash tun dead space - can be minimized
Kettle dead space - can be controlled, but I don't want trub in my fermentor, so I'm okay leaving behind 2 quarts
Hops absorption - could be controlled


For more info:
http://www.brewersfriend.com/faq/#brewsessions5

 

I'm guessing you mean stirring well at the beginning of the mash?

I'm usually in the low 90's with a 60 minute mash. I'm wondering whether it's worth starting the brew-day half and hour earlier to make up those few extra percent.

 

During the mash I usually go do something else, so sometimes the mashes run long

 

I just had this experience myself!
Up until the last two brews, I have been working with a 2.9L/Kg ratio, with a single batch sparge, and getting my aforementioned 62% efficiency.
For my 2nd to last brew, I only had a 2.0L/Kg ratio, but with a double batch sparge, and still hit 62%.
With my latest brew I was at first surprised to see that I had a 6% increase in efficiency (=>68%), but then realized I had a 3.6L/Kg ratio (with a single batch sparge). I overshot my sparge temp a bit too, but I highly doubt that had much to do with the significant increase in efficiency.
Rather, I agree that a thinner mash can lead to increased efficiency.

 

Yep, thinner and longer seem to be the way to go.

 

Did you record conversion efficiency in BF? This means adding a mash complete entry and entering first wort gravity and amount strike water.

Kai

 

No, unfortunately not. I will have to admit that I never measure SG pre-boil, so I really have no idea what my mash efficiency is...only brewhouse.

 

Measuring conversion efficiency will be your best tool to troubleshoot low efficiency into the kettle. It's easy when you have a refractometer since all you need is the gravity of the first wort after the mash has been stirred. The strike water volume should be known from the recipe.

TheZel66, I have done experiments with cold sparging where I did not see a significant efficiency impact. My best guess is that mashing thinner will give you a boost.

Kai

 

Single infusions with a modified fly sparge: 70% - 77%.

 

Strange efficiency experience today;

Brewed a recipe that I've brewed once before, only this time I managed to come in under gravity dispite adding extra sugar (@ boil) that wasn't in the previous version and mashing longer. Recipe called for 1.052 and I managed to hit 1.042.

Only things I did differently;
- Grains already in mash tun, added strike water to grains rather than adding grains to strike water. Did get some dough-balls, but broke them down thoroughly with a rigourous stir.
- Gravity sample taken from bottom of kettle and was full of protien gunk. Could that affect the reading?

 

Wouldn't hurt to take another gravity reading if there is still time.

As for the order of adding the grains and water to the mash tun, I do not think that would matter. Was the crush the same? What about thermometers - all calibrated?

 

Particulate matter in the sample does not effect the reading, only sugars that are dissolved in solution.