Robobrew/Brewzilla Discussion

[Bottoms_Up]

Has anyone considered what effect the "dead space" in a Brewzilla has on the "thickness" of the mash?

The 35 liter Gen 4 has exactly 2.0 liters of "dead space" below the screen of the pipe. This doesn't really affect the thickness of the mash and can be considered as part of the sparge water calculations.

But what about the volume of water between the outside wall of the pipe and the wall of the Brewzilla? This is not an insignificant volume of water. I took measurements and calculated this volume as being 18% of the volume inside the pipe. Since the grain is contained within the pipe, theoretically it shouldn't affect the thickness of the grain, but if you are calculating the water to grain ratio, don't you need to increase that by an additional 18% to account for the water outside the pipe and keep the water to grain ratio inside the pipe as desired?

 

[Sidman]

Curious if anyone has modded their malt pipe for gen 3 version to have filter holes along the sides at the bottom like the gen 4 malt pipe? I have a ton of batches in on my 65l v3 and it recirculates beautifully for a 5 gallon batch but really struggles with a decent og 10 gallon batch. I have ditched the overflow pipe and plugged the screen and use biab bag around the malt pipe and I'm typically lucky to get the pump flowing more than a quarter turn without overflowing on the sides. Would appreciate any help!
Cheers!

 

[DuncB]

Curious if anyone has modded their malt pipe for gen 3 version to have filter holes along the sides at the bottom like the gen 4 malt pipe? I have a ton of batches in on my 65l v3 and it recirculates beautifully for a 5 gallon batch but really struggles with a decent og 10 gallon batch. I have ditched the overflow pipe and plugged the screen and use biab bag around the malt pipe and I'm typically lucky to get the pump flowing more than a quarter turn without overflowing on the sides. Would appreciate any help!
Cheers!

I'm using a 70 Litre Guten so basically the same as yours. Bigger grain bills don't flow as well, I do use glucanase in my recipes which helps make the mash less gummy. Flow hasn't been too bad but majority of my mashes I'm aiming for a 25 litre batch and gravity up to 1.070.

 

[KegLand]

When in the hell is the 100L coming to the US?

Sorry for the long wait. We have got orders in the system for www.williamsbrewing.com and also www.morebeer.com so if you check with these guys they can give you a more accurate arrival time.

 

[KegLand]

Curious if anyone has modded their malt pipe for gen 3 version to have filter holes along the sides at the bottom like the gen 4 malt pipe? I have a ton of batches in on my 65l v3 and it recirculates beautifully for a 5 gallon batch but really struggles with a decent og 10 gallon batch. I have ditched the overflow pipe and plugged the screen and use biab bag around the malt pipe and I'm typically lucky to get the pump flowing more than a quarter turn without overflowing on the sides. Would appreciate any help!
Cheers!

If this is the case I would probably resort to stirring as you heat up. In the order Gen 3 I used to just stir more especially in the first 30min of mash time. You can also try heating up the strike water slightly more.

 

[Bottoms_Up]

Has anyone considered what effect the "dead space" in a Brewzilla has on the "thickness" of the mash?

The 35 liter Gen 4 has exactly 2.0 liters of "dead space" below the screen of the pipe. This doesn't really affect the thickness of the mash and can be considered as part of the sparge water calculations.

But what about the volume of water between the outside wall of the pipe and the wall of the Brewzilla? This is not an insignificant volume of water. I took measurements and calculated this volume as being 18% of the volume inside the pipe. Since the grain is contained within the pipe, theoretically it shouldn't affect the thickness of the grain, but if you are calculating the water to grain ratio, don't you need to increase that by an additional 18% to account for the water outside the pipe and keep the water to grain ratio inside the pipe as desired?

@KegLand do you have an answer to this question? Thanks.

 

[Sidman]

If this is the case I would probably resort to stirring as you heat up. In the order Gen 3 I used to just stir more especially in the first 30min of mash time. You can also try heating up the strike water slightly more.

Appreciate it and you Kegland! I have one of the extensions for the 65l and I see that you have a taller malt pipe for the extension. Does it have the same type of screen at the bottom?

 

[hungupdown]

@KegLand do you have an answer to this question? Thanks.

Has anyone considered what effect the "dead space" in a Brewzilla has on the "thickness" of the mash?

The 35 liter Gen 4 has exactly 2.0 liters of "dead space" below the screen of the pipe. This doesn't really affect the thickness of the mash and can be considered as part of the sparge water calculations.

But what about the volume of water between the outside wall of the pipe and the wall of the Brewzilla? This is not an insignificant volume of water. I took measurements and calculated this volume as being 18% of the volume inside the pipe. Since the grain is contained within the pipe, theoretically it shouldn't affect the thickness of the grain, but if you are calculating the water to grain ratio, don't you need to increase that by an additional 18% to account for the water outside the pipe and keep the water to grain ratio inside the pipe as desired?

Depends what you consider as "dead. space". It's really the amount of liquid left behind once your mash tun is drained, but brew software assumes all liquid under the false bottom is not returned to the kettle. That isn't always the case. The BZ, having a domed base with drain at bottom, maybe leaves just 0.5l behind.

Mash deadspace, is the unused water that's between outside of unperforated maltpipe & the BZ wall. This 4l, never normally gets circulated, except by thermal eddy's or diffusion, and only gets mixed in when the malt pipe is lifted.
Forcing circulation of this unused/deadspace water , by occasionally sticking the recirculation hose down one of the lift holes, will improve efficiency. As during mash, sugar concentration in the saturated grain, will gradually equalise with that in the wort, so a more dilute wort should extract more sugars.

Alternative is to keep recirculating through the grain, for a while, after the pipe is lifted, so the diluted wort can rinse off more sugars. But unless prolonged, it can't be as efficient.

 

[Bottoms_Up]

Depends what you consider as "dead. space". It's really the amount of liquid left behind once your mash tun is drained, but brew software assumes all liquid under the false bottom is not returned to the kettle. That isn't always the case. The BZ, having a domed base with drain at bottom, maybe leaves just 0.5l behind.

Mash deadspace, is the unused water that's between outside of unperforated maltpipe & the BZ wall. This 4l, never normally gets circulated, except by thermal eddy's or diffusion, and only gets mixed in when the malt pipe is lifted.
Forcing circulation of this unused/deadspace water , by occasionally sticking the recirculation hose down one of the lift holes, will improve efficiency. As during mash, sugar concentration in the saturated grain, will gradually equalise with that in the wort, so a more dilute wort should extract more sugars.

Alternative is to keep recirculating through the grain, for a while, after the pipe is lifted, so the diluted wort can rinse off more sugars. But unless prolonged, it can't be as efficient.

This is a bit complicated, and to my knowledge, has never been noticed or mentioned before, so maybe I haven't been clear enough.

There's no real terminology that I'm aware of for this "dead space", which is why I put quotes around it. Maybe it's better to call it "excess space", or even better, "unaccounted space", in the sense that it falls outside the calculation of a typical mash (grain + infusion). I'm referring to all of the liquid below the bottom screen of the malt pipe (2.0 liters in my system 35 liter Gen 4) as well as all of the liquid between the wall of the mash pipe and the wall of the Brewzilla, which itself, in my system, is 18% of the total volume of mash in the mash pipe.

In a closed mash tun, in order to calculate the amount of infusion water, you would first decide on a water to grain ratio, say 1.5 quarts per pound. The amount of water affects the thickness of the mash. But in the Brewzilla, you first have all the liquid under the mash pipe to consider (the 2.0 liters). Since it sits under the mash, it does not affect the thickness of the mash, but you still have to account for this volume when calculating the remaining amount of sparge water to use. This is later drained along with the wort that comes from the mash. This volume is not of much concern since it doesn't affect the mash thickness, and can readily be taken into consideration.

However, what IS of concern and does affect mash thickness is the amount of water/wort that exists above the bottom of the mash pipe and between the mash pipe and the outer wall of the Brewzilla. At first I thought that this amount would be negligible. But when I measured the space between, it amounted to 18% of the area within the mash pipe, which is indeed significant. Thus it would account for about 18% of the total volume of the mash (again within the mash pipe).

Now since the mash pipe contains the grain within it, the grain thickness is only dependent on the amount of water contained in the mash pipe. But if you were to calculate 1.5 quarts per pound of grain, 18% of that water would drain into the space between the malt pipe and the outer wall of the Brewzilla. This would therefore REDUCE the water to grain ratio inside the malt pipe by 18%, resulting in a much thicker mash than desired.

Thus I was wondering if anyone takes this into account when calculating the mash thickness? In other words, you would need to add 18% more infusion water to maintain the water to grain ratio at say, 1.5 quarts per pound of grain. I think that most home brewing software programs (e.g. BeerSmith) would not take that into account, so you would end up with a much thicker mash than desired.

Hope that makes better sense.

 

[micraftbeer]

I use Brewfather. Its equipment profiles have two terms relative to this:

1. Mash Tun Deadspace. It explains this as recoverable mash deadspace. Brewfather uses this mathematically like this... You define your desired mash thickness in qt/lb (in the Brewfather equipment profile), and it calculates a mash water volume. Then it adds this Mash Tun Deadspace value and this is the total volume of water Brewfather tells you to put in your "mash tun". In this case, that's just how much to add to your BrewZilla. I have 0.66 gallons in my profile for BrewZilla Gen4.

2. Mash Tun Loss. It calls this unrecoverable mash volume. This is wort left behind in your "mash tun" that doesn't make it into your "boil kettle". Mathematically, Brewfather takes your amount of Mash water added above, subtracts off the grain absorption (my profile has 0.479 qt/lb), then subtracts off this Mash Tun Loss to give you your pre-boil volume. Since BrewZilla mash tun = boil kettle, I have Mash Tun Loss set to 0.

Here's an example of my most recent brew:

• 3.8 Gal of mash water
• 10.3 lbs of malt
• Target 1.25 qt/lb mash thickness
• 3.6 Gal of sparge water

• Measured 6.76 Gal of pre-boil volume
• Measured pre-boil gravity of 1.049
• Measured 82.8% mash efficiency

 

[Bottoms_Up]

I use Brewfather. Its equipment profiles have two terms relative to this:

1. Mash Tun Deadspace. It explains this as recoverable mash deadspace. Brewfather uses this mathematically like this... You define your desired mash thickness in qt/lb (in the Brewfather equipment profile), and it calculates a mash water volume. Then it adds this Mash Tun Deadspace value and this is the total volume of water Brewfather tells you to put in your "mash tun". In this case, that's just how much to add to your BrewZilla. I have 0.66 gallons in my profile for BrewZilla Gen4.

2. Mash Tun Loss. It calls this unrecoverable mash volume. This is wort left behind in your "mash tun" that doesn't make it into your "boil kettle". Mathematically, Brewfather takes your amount of Mash water added above, subtracts off the grain absorption (my profile has 0.479 qt/lb), then subtracts off this Mash Tun Loss to give you your pre-boil volume. Since BrewZilla mash tun = boil kettle, I have Mash Tun Loss set to 0.

Here's an example of my most recent brew:

• 3.8 Gal of mash water
• 10.3 lbs of malt
• Target 1.25 qt/lb mash thickness
• 3.6 Gal of sparge water

• Measured 6.76 Gal of pre-boil volume
• Measured pre-boil gravity of 1.049
• Measured 82.8% mash efficiency

Thanks @micraftbeer, you have completely understand what I was trying to point out. It's good that Brewfather can be tricked into accommodating the excess space by using the "recoverable mash deadspace" profile option. I assume that most people using this "deadspace" would just add the space below the mashpipe and that's why I specifically mentioned the space around the mash pipe, because I don't think that most homebrewers are aware that that amount should also be added. Even if they were aware, I assume that they would likely have thought it to be negligible, as I used to. For their benefit, I have calculated that amount to be 18% of the volume within the mash pipe independent of the mash thickness. The volume includes both the infusion water plus the grain. There is a mathematical way this volume can be calculated fairly easily, which involves the displacement of the grain as well as the amount of water the grain absorbs.

In short, you add the grain volume to the volume of infused water, minus the volume absorbed. The mash grain displacement is 0.36 qt./lb. or 0.75 liters/kg. The water absorption ratio for grain is 0.10 gallons/lb. or 0.379 liters/lb. Once you calculate the volume, the recoverable dead sapce around the mash pipe (but not below it) is 18% of that volume. Then you add the volume below the mash pipe, which, for the 35 liter Gen 4 is 2.0 liters (0.53 US Gallons).

For a typical 5 gallon brew, according to my calculations, the total recoverable mash deadspace is about 4.3 liters or 1.14 US gallons. Thus your 0.66 gallons seems quite low.

 

[cactusgarrett]

There's no real terminology that I'm aware of for this "dead space"

It's "recoverable" vs "unrecoverable".

 

[micraftbeer]

Thanks @micraftbeer, you have completely understand what I was trying to point out. It's good that Brewfather can be tricked into accommodating the excess space by using the "recoverable mash deadspace" profile option. I assume that most people using this "deadspace" would just add the space below the mashpipe and that's why I specifically mentioned the space around the mash pipe, because I don't think that most homebrewers are aware that that amount should also be added. Even if they were aware, I assume that they would likely have thought it to be negligible, as I used to. For their benefit, I have calculated that amount to be 18% of the volume within the mash pipe independent of the mash thickness. The volume includes both the infusion water plus the grain. There is a mathematical way this volume can be calculated fairly easily, which involves the displacement of the grain as well as the amount of water the grain absorbs.

In short, you add the grain volume to the volume of unfused water, minus the volume absorbed. The mash grain displacement is 0.36 qt./lb. or 0.75 liters/kg. The water absorption ratio is 0.10 gallons/lb. or 0.379 liters/lb. Once you calculate the volume, the recoverable dead sapce around the mash pipe (but not below it) is 18% of that volume. Then you add the volume below the mash pipe, which, for the 35 liter Gen 4 is 2.0 liters (0.53 US Gallons).

For a typical 5 gallon brew, according to my calculations, the total recoverable mash deadspace is about 4.3 liters or 1.14 US gallons. Thus your 0.66 gallons seems quite low.

I approached the problem differently, but got pretty much the same answer. Rather than the displaced volume numbers you were talking, I just got my tape measure and measured different parts of the unit, malt pipe, and false bottom. So looking at my most recent brew, it looks like the recoverable deadspace was 1.24 gal, essentially the same as you calculated.

That means while I thought I had a 1.25 qt/lb mash, I had closer to a 1 qt/lb mash. I don't have a calibrated reference point or "gauge" to measure that. All I can say is that it was pretty typical mash thickness for me as I've brewed across different systems, including a standard 3V setup.

So now the question is if I update my BrewZilla profile to show 1.24 gal recoverable deadspace, and change my target mash thickness to 1.0 qt/lb, or if I just leave it like I have it. I am getting great mash efficiency 80+%, so I kind of want to leave well enough alone. But I know it will eat at me knowing I've got some innacurate values in there...

 

[DuncB]

That dead space between the malt pipe and kettle wall is a variable.
On the bigger unit I'm using a guten 70 which is basically same as brewzilla 65 version 3.
The space below the malt pipe base is 9 litres and you can adjust flow to change to say 6 litres with a gap between malt pipe base and the residual volume in kettle.
Hence no dead space between malt pipe and kettle wall and a third less below malt pipe.
You can adjust for this in brewfather.
Very useful trick to be done carefully!!

 

[Bottoms_Up]

I approached the problem differently, but got pretty much the same answer. Rather than the displaced volume numbers you were talking, I just got my tape measure and measured different parts of the unit, malt pipe, and false bottom. So looking at my most recent brew, it looks like the recoverable deadspace was 1.24 gal, essentially the same as you calculated.

That means while I thought I had a 1.25 qt/lb mash, I had closer to a 1 qt/lb mash. I don't have a calibrated reference point or "gauge" to measure that. All I can say is that it was pretty typical mash thickness for me as I've brewed across different systems, including a standard 3V setup.

So now the question is if I update my BrewZilla profile to show 1.24 gal recoverable deadspace, and change my target mash thickness to 1.0 qt/lb, or if I just leave it like I have it. I am getting great mash efficiency 80+%, so I kind of want to leave well enough alone. But I know it will eat at me knowing I've got some innacurate values in there...

Thats how I calculated mine. I measured the outside diameter of the malt pipe and the inside diameter of the Brewzilla. Then I calculated the areas of each and subtracted the difference. I then calculated the difference (which represents the area between the malt pipe and the inside wall of the Brewzilla) and divided it by the area within the malt pipe, which was 18%. Thus the volume of the area outside the pipe will always be 18% of the volume within the pipe regardless of how much malt you have.

You could also calculate the volume per centimeter or inch of the height of the mash, but you would have to know before-hand how high the mash will be. If you always make the same recipe, then you could use the same height each time. I just find it much easier to always calculate the volume before-hand. I don't use a homebrew recipe program and have written my own, so the calculation is built in.

 

[Bottoms_Up]

That dead space between the malt pipe and kettle wall is a variable.
On the bigger unit I'm using a guten 70 which is basically same as brewzilla 65 version 3.
The space below the malt pipe base is 9 litres and you can adjust flow to change to say 6 litres with a gap between malt pipe base and the residual volume in kettle.
Hence no dead space between malt pipe and kettle wall and a third less below malt pipe.
You can adjust for this in brewfather.
Very useful trick to be done carefully!!

I don't see how you can assume no dead space (recoverable space) between the malt pipe and kettle wall, unless you are not using a pipe?

 

[DuncB]

I don't see how you can assume no dead space (recoverable space) between the malt pipe and kettle wall, unless you are not using a pipe?

Using the sight glass and knowing where the bottom of the malt pipe is I can adjust flow so no liquid is in the gap between malt pipe and kettle wall.

 

[mashdar]

Using the sight glass and knowing where the bottom of the malt pipe is I can adjust flow so no liquid is in the gap between malt pipe and kettle wall.

Wow, interesting idea.

edit: do you find you have to adjust it often?

 

[DuncB]

Wow, interesting idea.

edit: do you find you have to adjust it often?

It needs watching during the early stages, my unit has 9 litres of liquid to just touch the base of the fitted malt pipe base, I do watch it like a hawk at first as I often step mash so the gelatinisation change affects flow.
Tend to use glucanase in most mashes to help flow and my controller I retrofitted to the guten stops the pump every ten minutes for two minutes allowing a drain down and so some liquor will go up the side of malt pipe at that stage. I have a split flow so that the whirlpool mixes the base of kettle and up the side of the malt pipe as well as recirculate. This means temp sensor works well and I get an audible warning with the light splashing sound as the liquor level falls to base of malt pipe and I can tweak.
But once it's going in the above 60 C stages of mash I don't need to adjust.

 

[Bottoms_Up]

Using the sight glass and knowing where the bottom of the malt pipe is I can adjust flow so no liquid is in the gap between malt pipe and kettle wall.

I don't follow. How does controlling the flow prevent the liquid from equlizing its pressure and finding the same level in the space between the pipe and the wall of the kttle wall?

 

[DuncB]

I don't follow. How does controlling the flow prevent the liquid from equlizing its pressure and finding the same level in the space between the pipe and the wall of the kttle wall?

The pump is capable if on full speed and flow through the grain bed is slow to pump the dead space below malt pipe dry.
Hence by throttling the pump outflow I can balance the rate of malt pipe pass through and refilling/ emptying.

 

[Bottoms_Up]

The pump is capable if on full speed and flow through the grain bed is slow to pump the dead space below malt pipe dry.
Hence by throttling the pump outflow I can balance the rate of malt pipe pass through and refilling/ emptying.

Ah, now I understand. Interesting option!

 

[hungupdown]

Can you send us any photos of the scorching? This is quite difficult to do as the watt density is quite low already. We the Gen 4 is even lower but the older 3.1.1 was still quite low watt density too.

I had thermal cutout, after (internal sensor) temperature exceeded 120°C, with scorching on BZ 35l gen4 with HED, while doing a Weisenbock (50% wheat) 23L batch. Very burnt/smokey flavour, was going down the drain, until I found someone that likes smokey (scottish whiskys) that would take it.
It was taking 100% heat to maintain boil, I think due to the insulating layer.

The mash had been well stuck, and took lots of stirring to drain at all, which I think must have caused a lot of flour to drop out of the malt. And mostly settled out on base, due to the very slow recirculation rate.
After final draining, found the gap between the HED and the base was completely full of burnt flour, apart for a few narrow channels, which the very slow, intermittent, recirculation kept open
.
Photo is of (just biggest solid pieces) of the chipped out crud remomed, placed on a fermenter bucket lid (37cm dia). The shiney black, very burnt, side was underneath (against heater).

 

[hungupdown]

Has anyone considered what effect the "dead space" in a Brewzilla has on the "thickness" of the mash?

The 35 liter Gen 4 has exactly 2.0 liters of "dead space" below the screen of the pipe. This doesn't really affect the thickness of the mash and can be considered as part of the sparge water calculations.

But what about the volume of water between the outside wall of the pipe and the wall of the Brewzilla? This is not an insignificant volume of water. I took measurements and calculated this volume as being 18% of the volume inside the pipe. Since the grain is contained within the pipe, theoretically it shouldn't affect the thickness of the grain, but if you are calculating the water to grain ratio, don't you need to increase that by an additional 18% to account for the water outside the pipe and keep the water to grain ratio inside the pipe as desired?

I'd worked out, there's 4L of water outside (the unperforated part) of my BZ35L_g4 malt pipe, when final level comes to the 23L mark.

That 4L is 17.4% of total water, or 21% of the 19L that's within the malt pipe and base, - if it was all water.
But will be higher percentage when part of that volume is the grain, which (in my typical mash) accounts for 3L. Then the 4L is 25% of the 16L within the malt pipe and base.

The water within the malt pipe, determines water to grain ratio, for the mash thickness. Enough water is needed here, so the mash isn't too thick.

Total water (whatever gets mixed during recirculation) determines water to grain ratio, for enzyme concentration and sugar extraction, calculation. That total includes water under the false bottom, and water around the perforated part of the malt pipe. Too much total water, and the over diluted enzymes maybe slow to convert starches (particularly where high % unmalted grains used).

Graham Wheeler gives water range as 1.5 - 3.5L /kg grain, normally 2 - 2.5L /kg.
Brewfather default equipment profiles I've looked at, use 3.0 - 3.2L /kg (on top of bottom deadspace).

Water around the unperforated part of malt pipe, never gets recirculated, apart from any diffusion/convection. This (25%) water stays unused, till the malt pipe is lifted and it gets mixed in, then just diluting the mash without ever achieving anything usefull.

It can be put to good use though, by doing outer-recirculating (around the malt pipe) so diluting the wort (by 25%). A diluted wort will draw more sugars from the grain. To achieve this, occasionally switch the recirc pipe from the grain, to sticking it down one of the lifting holes, for a percentage of the time.
At least do this during the mash out temperature step. The longer the diluted recirculation the better, so maybe the full mash, except where early enzyme dilution might be too great.
In a no sparge mash, this should result in 25% more efficiency.

I've done a mod, and now have two recirculation pipes. The second being a 2m silicone pipe fitted on the (pumped) drain spigot, the tap lever and recirc valve then balance the two recirculation flows.
My recirculation can always total 100% flow, even while doing grain bed rest after dough in (with no flow through grain for 20min). The outer recirc means the malt pipe is heated from all round as well as from below, so maintaining set temperature better, and speeding up temperature steps. Fast flow over the heaters, means any temperature overshoots are less extreme, and helps prevent any rinsed-out flour settling on the base (most keeps circulating, until filtered by bed).

I've started with trying these flows (divided between grain bed % : outer %).
During grain bed rest (20min) 0% : 100%
Recirc mash (first 20 min) slow rate : rest of 100%
Mash (remaining time & mashout) highest rate without wort rising : rest of 100%.

The 2m pipe is sometimes also handy when filling fermenters up on the bench (which was just too high for the sparge arm hose to reach).
The pipe's removed (for final cleaning/draining) by just unscrewing the spigot, but I might invest in a camlock coupling.

A double sided velcro loop, fixed around top of the recirculation/sparge arm, gives an easy way to support the second pipe.

 

[hungupdown]

Using the sight glass and knowing where the bottom of the malt pipe is I can adjust flow so no liquid is in the gap between malt pipe and kettle wall.

Differential pressure = the pressure above the bed – the pressure below the bed. As caused by any difference in levels between inside and outside the malt pipe.

Crispmalt cover how this impacts bed compression; reduced run off; and collapse, in one of their how-to's Oats - Differential pressure

With the BZ fairly tall & narrow pipe, differential pressure can have more impact (than with wide shallow designs). So I always keep any difference under 2cm (and never use the top screen).

If the bed ever compresses, it will never recover, and the run off stays reduced.
And it's why a floating sparge can have the fastest flow (wort removed from floating grain, at same rate sparge water added).

 

[DuncB]

I suppose on my bigger unit I have a proportionally greater surface of mash to volume ratio or shallower malt bed.

 

[micraftbeer]

I just brewed on Friday. Thinking about the discussion in this thread, as @Bottoms_Up got me to calculate/confirm the volume outside the malt pipe, I felt my "1.25 qt/lb" mash (using 0.66 gal of recoverable deadspace instead of 1.25 gal) was a drier mash. Prior to thinking about this deadspace, my memory was always that it was about the same thickness as when I targeted 1.25 qt/lb in my 3V setup.

But, that was just during mash in, before I was circulating. So once I had stirred everything up well for 10 minutes with my long stainless spoon, and ensured there were no dry spots, I started recirculating. I don't have a sight glass like @DuncB but of course the logic makes sense that the water level in this dead space will go down while the pump is running. And since I just use the stock recirc arm and put all the recirc flow on top of my mash (and yes, I use the top screen, too), while recirculating, I don't have a dry mash. So the realtime deadspace during my mash is going to be less than the 1.25 gal I calculated for my typical 5 gal batch. I don't know what it is, but since my efficiency is good and I'm not suffering any stuck mashes, I'm leaving it alone.

Reading the posts about people setting up multiple recirc paths inside and outside the malt pipe like @hungupdown or moving the recirc hose during mash to be sometimes inside/sometimes outside like some others have mentioned, I wonder if that effort results in improved efficiency gains? I regularly get 80+% mash efficiency, and I don't do any of this babysitting during the mash. But my numbers are doing a batch sparge, so may be different answer if comparing to full volume mash folks. But I'm interested if anyone that does things to deal with this volume outside the malt pipe have done with/without their interventions and captured the efficiency effect?

 

[Airborneguy]

Looks like my pump is blocked up again. I’m using hop bags from now on.

 

[hungupdown]

Looks like my pump is blocked up again. I’m using hop bags from now on.

I've had blocked pump, after adding boil hop pellets (while pump not running).

Now always using large hop spider, and recirculate through it at full flow. Usually works fine, but once was threatening to overflow from spider, which needed reduced flow. Now keep an eye on it, when there's a lot of hops.