Making a malt pipe out of a 55L keg

[squirt in the turns]

I'm thinking about swapping my grain bag for a malt pipe and doing recirculation. Has anyone made a malt pipe out of a 55L commercial keg, or foresee any problems with the idea? Unlike the malt pipe in, for example, the Brewzilla, the sides aren't straight (keg has those bulges). I wonder if they would encourage channelling down the sides. Or even discourage it? I'm sure this type of keg has served as a mash tun in many a 3V system over the years without problems so I reckon it's a good idea.

I brew in a 70L stainless pot that I got from Craftbrewer years ago (I don't think they sell them anymore). It's 450mm h x 450mm dia.

I'm not using the keg for anything else but don't want to wreck it for nothing if this is a dumb idea. I was thinking I'd cut the top off, drill some big holes in the bottom, and add a domed false bottom with the 1/2" hole in the centre.

I'd aim for the height of the malt pipe to be such that the lid for the 70L pot practically touches it - i.e. the lid will ideally seal against the rims of both the inner and outer vessels. This will maximise the capacity of the malt pipe, minimise heat loss, and minimise gas movement over the wort/mash surface to minimise oxidation (for those that buy into that whole thing). This should give me a malt pipe with almost identical dimensions to the one included with the 65L Brewzilla. I'll have more space between the walls of the pot and the malt pipe than the Brewzilla, so more wort not in the pipe and therefore a thicker mash, but I don't think this will cause any problems.

 

[MHB]

I'm a bit bemused, trying to figure out what you are hoping to achieve.
There appear to be two options and they don't really work together for me. If you are replacing the bag with a pipe, the liquor outside the pipe wont readily mix with the mash inside the pipe. With a bag it will spread out to occupy the full volume of the pot (at least it should) so all the grain and water (liquor) are mixed together.
With a malt pipe there is a pump that causes the mixing so you get the same effective L:G ratio (Liquor to Grist (water to grain)), 1V systems depend on the pumping and a controlled element to keep the temperature stable or do steps.

Looks to me like without a pump you will be going in a different direction, if you are going to use a pump why put the malt pipe in the kettle, better to stand it along side and set up a recirculating system. That would give you more capacity in either volume or strength and you are back to looking at a classic RIMS or HERMS type of system.
There are plenty of good designs for them out there that might be worth a look.
Mark

 

[squirt in the turns]

I'm a bit bemused, trying to figure out what you are hoping to achieve.
There appear to be two options and they don't really work together for me. If you are replacing the bag with a pipe, the liquor outside the pipe wont readily mix with the mash inside the pipe. With a bag it will spread out to occupy the full volume of the pot (at least it should) so all the grain and water (liquor) are mixed together.
With a malt pipe there is a pump that causes the mixing so you get the same effective L:G ratio (Liquor to Grist (water to grain)), 1V systems depend on the pumping and a controlled element to keep the temperature stable or do steps.

Looks to me like without a pump you will be going in a different direction, if you are going to use a pump why put the malt pipe in the kettle, better to stand it along side and set up a recirculating system. That would give you more capacity in either volume or strength and you are back to looking at a classic RIMS or HERMS type of system.
There are plenty of good designs for them out there that might be worth a look.
Mark

I should have been more clear in my original post: I am intending to recirculate using a pump, and the malt pipe will replace the bag. It will be functionally equivalent to a Brewzilla, Grainfather, or many of the DIY 1V electric recirculating systems that others have built. My concerns were really just around the shape of the inner malt pipe vessel - namely that the sides won't be straight.

 

[MHB]

OK well a keggle with a domed false bottom in it is far from a new configuration and works well. Personally I would use the smaller of the two commonly available domed bottoms (10"). Using the smaller dome makes for a more balanced flow through the grain bed, pretty much eliminating the walling effect you are concerned about.
If you mount a bolt or a bit of all thread in the center bottom and use a wing nut and a washer it makes holding down and taking out the false bottom for cleaning way easier.

I really don't see why you wouldn't set it up as a 2V system, saves having to pull the malt pipe out and gives you way more options in how much, how strong a beer you can make...
I think there is a bit more engineering going on in a well made 1V than you think.
Mark

 

[camNZ]

I should have been more clear in my original post: I am intending to recirculate using a pump, and the malt pipe will replace the bag. It will be functionally equivalent to a Brewzilla, Grainfather, or many of the DIY 1V electric recirculating systems that others have built. My concerns were really just around the shape of the inner malt pipe vessel - namely that the sides won't be straight.

Why can't you recirc with a bag?

 

[MHB]

You tend to get lots of wort going down one path and other bits of the grist not getting much at all.
With a pipe all the wort has to travel through (top to bottom or bottom to top in a BM), means everything gets mashed evenly (well given you do the basics right).
Mark

 

[camNZ]

You tend to get lots of wort going down one path and other bits of the grist not getting much at all.
With a pipe all the wort has to travel through (top to bottom or bottom to top in a BM), means everything gets mashed evenly (well given you do the basics right).
Mark

Oh I see we're talking about single vessel, to sparge you have to lift the bag out and let it hang above "BK"?

Sorry 3v brewer here and the OP said recirculation. I can't see any reason you can't recirc with a bag, I plan on doing this to help with the clean up.

I agree with Mark, you would be much better off using the keg to make a 2v system. Your efficiency will improve dramatically.

 

[squirt in the turns]

OK well a keggle with a domed false bottom in it is far from a new configuration and works well. Personally I would use the smaller of the two commonly available domed bottoms (10"). Using the smaller dome makes for a more balanced flow through the grain bed, pretty much eliminating the walling effect you are concerned about.
If you mount a bolt or a bit of all thread in the center bottom and use a wing nut and a washer it makes holding down and taking out the false bottom for cleaning way easier.

I really don't see why you wouldn't set it up as a 2V system, saves having to pull the malt pipe out and gives you way more options in how much, how strong a beer you can make...
I think there is a bit more engineering going on in a well made 1V than you think.
Mark

Thanks for your input, Mark. I've previously built a 4V HERMS, (subsequently sold off most of the components). My motivation for this project is to keep the small footprint (both while being stored and in use) of my one-pot BIAB system, while gaining the precise temperature control, ability to step mash, and other benefits of a PID controlled system with recirculation that I had with the larger system. I don't really understand yours and camNZ's recommendation to make it a 2V system, which realistically would need to be a 3V system as I would need to sparge, given that to produce a 40L batch of 1.050 wort, the 50L keg mash tun would not have sufficient capacity.

Would you make the same 2V recommendation to everyone considering building or buying an electric 1V recirculating system?

I already hoist the grain bag using a pulley, so hoisting a malt pipe instead is a non-issue. I BIAB full volume mash (no-sparge) 40L batches with reasonable efficiency at the moment, so I am hoping that replacing the bag with a malt pipe is going to work without too many issues.

I appreciate that if I want to no-sparge 40L batches, I'll be limited in how high an OG I can hit. I usually only do single (20L) batches of bigger beers anyway. My proposed keg conversion would yield a malt pipe with almost identical dimensions to the one from the 65L Brewzilla, and the manual claims that it can hold 16 KG of grain, so I would not expect capacity/volume to be too much of a limiting factor.

Anyway, back to the design: would there be benefit to going even smaller with the domed false bottom? Clever Brewing do a 9" version, although it's out of stock at present. The keg that will become the malt pipe is a narrower model, approx 360mm in diameter.

The solution I'm imagining is an 18mm hole in the centre of the malt pipe/keg bottom, through which I'll put an externally threaded 1/2" BSP stainless pipe/nipple secured with a nut on each side of the keg bottom. The false bottom will fit over the threaded pipe (false bottom comes with a hole in the centre). Screwed to the pipe over the top of the false bottom (keeping it locked down) will be a female BSP hose barb, followed by a length of silicone hose with a float and a filter on top, to serve as an overflow pipe. In the malt pipe/keg bottom, around the central hole for the overflow, I'll make 4 larger holes with a 40mm punch, to allow the malt pipe to drain. Wort return to the top of the malt pipe will be via an SS Brewtech manifold.

If I understand the function of the overflow in the Grainfather/Brewzilla/Guten, etc, it is to prevent the pump and element from running dry. What I don't understand is why these systems seem to default to recirculating fast enough that a significant volume of wort flows down the overflow (see this video, for example). This seems pointless to me. I would want to throttle the recirculation rate so that the wort level in the malt pipe remains below the overflow. Unless there's some benefit I'm missing to having wort continually overflowing? I understand a lot of Brewzilla users do away with the overflow pipe anyway?

 

[MHB]

I have a 1V system and do some commercial brewing on another, both Baumeister's, so no I have no problems with well designed 1V systems. Having said that I have seen a lot of the other 1V systems and generally think (Flame Suit On) they are pretty crappy.
One of the reasons you note about how much wort runs down the sides. Unless as above you can cut that flow down so all of the wort is going through the malt, a brewer has no way of knowing if any is or its set like stone and not getting liquor through the grain bed at all.
There are a few other design features that I am not too impressed with but they are cheap so will no doubt be the best thing ever, and I'm clearly wrong. Meh some have some cleaver bits and pieces but in general I'm less than impressed.

Whether or not you put the malt pipe in the kettle or stand it along side is just a decision for you. Note that a keg malt pipe will be around 10kg add that to the load of malt and water and lifting it up is going to be an effort, I would want a winch or at least a double pully.
You would still need a HLT if you want to sparge.
I have made heaps of very similar mash tuns and have found that the 10" domed bottom worked well. Better than the 12" in this application but I haven't tried a 9" one. As big as you can would appear to be the best option so for me the 10" is probably the goldilocks' answer.
You might find this handy, I get it from Geordi they are 150mm long.

A 2V system using the parts you have (Pot and Keg) would let you make bigger batches, especially if you are using the kettle as a reservoir, you could in effect start with say 65L of water in the kettle and up to say 16kg of malt in the pipe. Temp control the liquor in the kettle and pump over the top of the malt pipe allowing it to gravity return.
With a little care you should be able to get somewhere close to 50L of 1.080-1.085 wort (preboil), If you put the pipe inside the pot, then you get about half of that. Well quick finger count says 50L at 1.038.
Mark

 

[Grmblz]

What I don't understand is why these systems seem to default to recirculating fast enough that a significant volume of wort flows down the overflow (see this video, for example). This seems pointless to me. I would want to throttle the recirculation rate so that the wort level in the malt pipe remains below the overflow. Unless there's some benefit I'm missing to having wort continually overflowing? I understand a lot of Brewzilla users do away with the overflow pipe anyway?

The brewzilla has a ball valve on the recirculation pipe, I think a lot of folks don't understand its purpose, and use it as an on/off device, it can however be used to regulate the flow of wort over the grain bed such that the overflow pipe never comes into play, as you point out however if you get a stuck mash then it becomes a safety device of sorts for the pump/element, you have to cater for those that don't have a clue, but want to brew. "chuckles"

 

[squirt in the turns]

I have a 1V system and do some commercial brewing on another, both Baumeister's, so no I have no problems with well designed 1V systems. Having said that I have seen a lot of the other 1V systems and generally think (Flame Suit On) they are pretty crappy.
One of the reasons you note about how much wort runs down the sides. Unless as above you can cut that flow down so all of the wort is going through the malt, a brewer has no way of knowing if any is or its set like stone and not getting liquor through the grain bed at all.
There are a few other design features that I am not too impressed with but they are cheap so will no doubt be the best thing ever, and I'm clearly wrong. Meh some have some cleaver bits and pieces but in general I'm less than impressed.

Whether or not you put the malt pipe in the kettle or stand it along side is just a decision for you. Note that a keg malt pipe will be around 10kg add that to the load of malt and water and lifting it up is going to be an effort, I would want a winch or at least a double pully.
You would still need a HLT if you want to sparge.
I have made heaps of very similar mash tuns and have found that the 10" domed bottom worked well. Better than the 12" in this application but I haven't tried a 9" one. As big as you can would appear to be the best option so for me the 10" is probably the goldilocks' answer.
You might find this handy, I get it from Geordi they are 150mm long.
View attachment 119991
A 2V system using the parts you have (Pot and Keg) would let you make bigger batches, especially if you are using the kettle as a reservoir, you could in effect start with say 65L of water in the kettle and up to say 16kg of malt in the pipe. Temp control the liquor in the kettle and pump over the top of the malt pipe allowing it to gravity return.
With a little care you should be able to get somewhere close to 50L of 1.080-1.085 wort (preboil), If you put the pipe inside the pot, then you get about half of that. Well quick finger count says 50L at 1.038.
Mark

You've given me pause for thought, Mark. I think my 50L keg is too narrow to make a good malt pipe for the 70L pot I'm working with, especially for no-sparge double batches. I would have thought that a malt pipe that barely fits in the outer vessel is probably optimal, being analogous to a bag which fills the volume of the BK, the principle differences being that the pipe can't be squeezed (probably resulting in lower efficiency if no-sparging), while the bag may encourage excessive channeling if recirculating. If I revisit this idea in the future I'll try to souce a wider vessel to convert to a malt pipe; maybe a more squat keg (the type the Keg King kegmenters are made from).

Also, I had all the bits laid out and realised my SS Brewtech stainless manifold is too wide to fit in the keg.

So, I think I'll sell the keg and stick with BIAB for now. BUT, I am going to give recirculation a go and see what happens - plenty of people seem to be doing it fairly successfully. I hope that using the manifold and controlling the return rate will help to mitigate channeling. I also already have a March pump, hoses, PID controller and external heat exchanger, so I don't have much to lose (unless I ruin a batch). Using the external HX to heat the wort means I don't need to worry about keeping the bag away from the BK elements, or scorching the wort during a protein rest, for example.

 

[eamonnfoley]

The 50L keg is a heavy vessel to be pulling in out of the 70L pot, taking away for cleaning etc. 2 vessel K-RIMS is the optimal use of the 2 vessels. 50L keg as mash tun, 70L boiler/HLT. Only need one pump if the MT is placed higher than boiler/HLT.