BZ gen4 outer recirculation mod

[peterpiper]

Just wondering if this sounds practical, or if anyone's come across any alternative methods?

I'm thinking of putting a silicone hose on the tap, to act as a second recirculation path, going around outside of the malt pipe to circulate water from the dead space there.
At the moment I alternate the existing hose between recirculation through the mash, and being poked into one of the lifting holes ('outside circulation'). For two reasons:

1)
After a stir during grain in, I let the bed rest, while the grains to swell up. For maybe 40- 60min, before recirculating through the mash. Earlier seems to flush out flour, and risk getting a stuck mash (especially with wheat beers).
Outside circulation at max flow, while the bed is resting, helps greatly with getting to or maintaining temperature. Instead of the mash being heated from just the bottom end, there's heat from all round as well.

2)
Theres a lot of 'dead' water sitting between outside of the malt pipe (O.D. 27cm), and the wall (I.D. 30cm). With a 27l total mash volume, height of water against unperforated pipe, is around 30cm.
So the dead volume is around 3.142 x 28.5 x 1.5 x 30 = 4030 cm³ or just over 4l.
I'd seen a post from someone who, after the mash finished, tried siphoning out the water from the gap (not this model). It still looked like tap water!

Mash efficiency should be much better if the dead space water is properly recirculated in some way, rather than just relying on convection.
You'd then have, say the full 20l of mash water being used, rather than just 16 of the 20. The 16l, being higher SG (would extract fewer sugars) and just be mixed with the mostly unused 4l when the malt pipe is lifted.

A second recirculation pipe, coming from the tap, would mean you then have two valves to control how the recirculation flow is divided.
A snag would be difficulty in draining the extra pipe. Would maybe want a dish on the floor. A danger or worry, would be the pipe falling down, if left running while unattended.

But I'm also considering re-plumbing the tap, to before pump, in case of any pump blockage. So might, wait until sure I'm not getting any late blockages (using a hop spider).

Alternatives might be some sort of T piece on the existing hose, or just hoping that fast recirculation (late on) will overflow through the lift holes. But that tends to carry some grain down, even if using the top screen.
It doesn't take much grain, for the tannins extracted during boil to cause noticeable astringency.

Suppose a stainless barbed T or Y connector, with different branch sizes giving unequal flows, would be simpler than adding extra valves.
Pipes could then go: both to mash; both to outside; slow to mash & fast outside; or slow to outside & fast to mash.
Probable downside, would be connector not fitting through lid hole.

Or if anyone's already tried it, do equal size branches work well?

 

[foxy]

1) If that is how you want to mash just carry on doing that, everyone has their own ideas.
2) Doesn't make any difference to the mash if the water surrounding the grain basket isn't 'theoretically' being pulled into the pump, which I disagree with.
If you mash out, lauter and sparge, you will be getting a higher efficiency through a more fluid flow over the grain bed washing out the sugars

 

[Caramel Ox]

I disagree about the volume of dead water - if the level in the malt pipe is higher during recirculating than at rest then that extra volume must come from the side gap. You could vary the recirculating rate to build exactly the level you wanted above the grain.

 

[RoomWithABrew]

@peterpiper

I have fitted a three way valve into the ascending metal pipe. Taken the tap out and changed this for a whirlpool fitting. Then i connect to this via camlock and half inch silicone. Allows me to recirculate over the top and mix the dead space whilst mashing. Most importantly it mixes the flow over the AIO temp sensor in the base.
After boil I connect in the counter flow chiller to the whirlpool loop so I can chill and whirlpool.
Then disconnect at the whirlpool and chill transfer into the fermenter.
The recirculation has the valve for flow control and obviously a valve on the outside of kettle at the whirlpool so flow can be adjusted at each part.
This picture I've also fitted the hop rocket.

 

[jambop]

@peterpiper

I have fitted a three way valve into the ascending metal pipe. Taken the tap out and changed this for a whirlpool fitting. Then i connect to this via camlock and half inch silicone. Allows me to recirculate over the top and mix the dead space whilst mashing. Most importantly it mixes the flow over the AIO temp sensor in the base.
After boil I connect in the counter flow chiller to the whirlpool loop so I can chill and whirlpool.
Then disconnect at the whirlpool and chill transfer into the fermenter.
The recirculation has the valve for flow control and obviously a valve on the outside of kettle at the whirlpool so flow can be adjusted at each part.
This picture I've also fitted the hop rocket.View attachment 93304

So with the hop rocket can you use that for multiple hop additions? Like say three different timed additions as in a normal boiler or do they all have to be added as one addition ?

 

[RoomWithABrew]

The hop rocket is basically a homebrew hop back. Great with whole cones but can be pellets. Really used for aroma additions at transfer to fermenter.
I also use it for containing elderflowers a flameout addition in a saison.
Loose in the boiler they block the pump quicker than you can say " I wish I hadn't done that"

 

[peterpiper]

1) If that is how you want to mash just carry on doing that, everyone has their own ideas.
2) Doesn't make any difference to the mash if the water surrounding the grain basket isn't 'theoretically' being pulled into the pump, which I disagree with.
If you mash out, lauter and sparge, you will be getting a higher efficiency through a more fluid flow over the grain bed washing out the sugars

Pumping faster than liquid is draining through the grain bed, can drop the surrounding level, as depth above the bed increases.
But as the surrounding water level goes below that in the malt pipe, that is putting weight on the grain bed and compressing it. The more its crushed, the more likely a stuck mash or sparge.

If carried to the extreme, where the level dropped below base of malt pipe, then full weight of grains + nearly the full weight of mash water, is all resting on the malt pipe.
If the wort is being drained by lifting the malt pipe, doing this slowly is recommended, to avoid crushing the grain bed.

A high efficiency, floating fly sparge, works by gradually draining wort, at same rate as sparge water is being added, to maintain surrounding water level at around an inch above grain.
In BZ, I sometimes achieve that by pumping the wort out as I sparge, rather than lifting the malt pipe to drain.

 

[peterpiper]

@peterpiper

I have fitted a three way valve into the ascending metal pipe. Taken the tap out and changed this for a whirlpool fitting. Then i connect to this via camlock and half inch silicone. Allows me to recirculate over the top and mix the dead space whilst mashing. Most importantly it mixes the flow over the AIO temp sensor in the base.
After boil I connect in the counter flow chiller to the whirlpool loop so I can chill and whirlpool.
Then disconnect at the whirlpool and chill transfer into the fermenter.
The recirculation has the valve for flow control and obviously a valve on the outside of kettle at the whirlpool so flow can be adjusted at each part.
This picture I've also fitted the hop rocket.View attachment 93304

Looks a nice setup.

Not sure how you've arranged flows through the Chiller. Does chill water go in at the wort out end?

 

[peterpiper]

2) Doesn't make any difference to the mash if the water surrounding the grain basket isn't 'theoretically' being pulled into the pump, which I disagree with.
If you mash out, lauter and sparge, you will be getting a higher efficiency through a more fluid flow over the grain bed washing out the sugars

If liquid surrounding the malt pipe is more dilute, and it's only fully mixed in once the malt pipe is raised, then only any vorlauff after raising would get efficiency benefits from the dilution. If dilute, then it's obviously unused during mashout.

I'm not sure if the "more fluid flow" you’ve mentioned, referrs to vorlauff after raising malt pipe.
Vorlauff after raising, would perhaps need to be long to get same sugars from grain centres as a 60min mash with more dilute wort. But then some people prefer lower mash water ratios anyway.

 

[RoomWithABrew]

Looks a nice setup.

Not sure how you've arranged flows through the Chiller. Does chill water go in at the wort out end?

Yes it does straight from the cold tap. More effective counter flowing.

 

[foxy]

If liquid surrounding the malt pipe is more dilute, and it's only fully mixed in once the malt pipe is raised, then only any vorlauff after raising would get efficiency benefits from the dilution. If dilute, then it's obviously unused during mashout.

I'm not sure if the "more fluid flow" you’ve mentioned, referrs to vorlauff after raising malt pipe.
Vorlauff after raising, would perhaps need to be long to get same sugars from grain centres as a 60min mash with more dilute wort. But then some people prefer lower mash water ratios anyway.

Yes as mash out temperature is 77C the viscosity is lower, the reasoning for the vorlauf is to remove any debris outside of the grain pipe.

Pumping faster than liquid is draining through the grain bed, can drop the surrounding level, as depth above the bed increases.
But as the surrounding water level goes below that in the malt pipe, that is putting weight on the grain bed and compressing it. The more its crushed, the more likely a stuck mash or sparge.

If carried to the extreme, where the level dropped below base of malt pipe, then full weight of grains + nearly the full weight of mash water, is all resting on the malt pipe.
If the wort is being drained by lifting the malt pipe, doing this slowly is recommended, to avoid crushing the grain bed.

A high efficiency, floating fly sparge, works by gradually draining wort, at same rate as sparge water is being added, to maintain surrounding water level at around an inch above grain.
In BZ, I sometimes achieve that by pumping the wort out as I sparge, rather than lifting the malt pipe to drain.

The pump can only pump the liquor at the same amount it is draining, it can't pump any more out than what is going in. Throttling the flow will cause heat loss, especially on a Brewzilla.
To Keep the grain from compacting on the bottom just use a paddle occasionally, that will help keep an even temperature as well.

 

[peterpiper]

The pump can only pump the liquor at the same amount it is draining,....

It can often easily pump more than the amount draining through malt pipe, if the flow is opened too far.
Initially level around malt pipe will drop, as level over malt increases, it will eventually empty under bottom and run pump dry.

There's plenty of info on differential pressure = the pressure above the bed – the pressure below the bed. And how it can collapse the grain bed.
eg CrispMalt article: Oats - Differential pressure

 

[foxy]

It can often easily pump more than the amount draining through malt pipe, if the flow is opened too far..
Initially level around malt pipe will drop, as level over malt increases, will eventually empty under bottom and run pump dry.
There's plenty of info on differential pressure = the pressure above the bed – the pressure below the bed. And how it can collapse the grain bed.

eg Oats - Differential pressure

There is plenty of info on keeping the grain gently in suspension and not allowing it to settle for the first 20 minutes, after that time the starch has converted to sugar, and let the mash rest. I agree that any flaked adjuncts will notoriously clog the grain bed so it is wise to be extra vigilant when using them. But it's a case of each to their own.