Mash cap and re-circulation

[JDXX1971]

Ok I have been reading a bit here and there when the topic of LoDo comes up, which it does quite often it seems. Now most of these conversations come with a certain amount of drama that makes me a little stand offish about participating. Now that Yooper has started this thread I am going to get a little more involved.

My recirculating BIAB system as it sits is set up to under let the mash water into the mash tun from a 10 gallon cooler. I preheat the water in the mash tun and then pump it to the cooler, load the grains in the bag and pump the water back under letting the grain in the mash tun. I have thought about boiling the water first per the LoDo technique and adding a mash cap. I currently use a Loc Line ring for recirculating.

So, I want to see what everyone is using for a mash cap and re-circulation.

 

[Big Monk]

You can go at least two different routes with mash caps:

1.) cap with built in recirculation port
2.) recirculation port in kettle with floating lid

The former will most likely require some sort of gasket to fix it in place at the top of the mas as the fittings and recirc manifold (I use locline and SS fittings) make it too heavy to float. The latter requires only that you have a fix inlet in the kettle so the cap will float.

It’s up to you what your system will handle, whether it be retrofitting equipment or purpose built stuff. We only recommend that you do cap, the implementations are so varied that we shy away from hard recommendations.

Good luck and welcome to the conversation.

 

[schematix]

I built mine from spare parts. It is very very marginal on its buoyancy, but this question spurred me to light weight all the fittings so hopefully it’s better next time. I had almost 300g or fittings I just reduced down to 140g, so hopefully that makes it better.

It’s a 15G boiler maker lid, inverted, with a male cam lock in either side. I have 1/2” not male and female cam locks sandwiched with silicone o rings to make the bulkhead. Locline under the liquid level for recirc return.

I put the cam lock on the locline because I also use this piece in another process and wanted it easily moved.

 

[JDXX1971]

Thank you for the reply @RPIScotty,

Currently I have my re circulation port in the lid of my kettle, I would keep it there most likely and do something like what you describe in option #1. I would like to see how some others have accomplished keeping the cap in place/afloat.

 

[JDXX1971]

I built mine from spare parts. It is very very marginal on its buoyancy, but this question spurred me to light weight all the fittings so hopefully it’s better next time. I had almost 300g or fittings I just reduced down to 140g, so hopefully that makes it better.

It’s a 15G boiler maker lid, inverted, with a male cam lock in either side. I have 1/2” not male and female cam locks sandwiched with silicone o rings to make the bulkhead. Locline under the liquid level for recirc return.


View attachment 548416View attachment 548417
View attachment 548418

I put the cam lock on the locline because I also use this piece in another process and wanted it easily moved.

I was thinking about something pretty much exactly like that. Be sure to report back how it works with the weight reduction. I am thinking now looking at your set up that I could probably afford to dedicate a short section of loc line to the bottom of the mash cap with only a single cam lock on top. That should lighten it up quite a bit more. Then I would connect from my current re circulation port in the kettle lid with the rest of my loc line and or silicone tubing. Now to find lids to use for mash caps.

 

[schematix]

Stainless cake pans are a popular and inexpensive choice. I would have gone that route but I can’t find one big enough for my 20G MLT. Turns out my unused 15G lid was a perfect fit for the 20G.

 

[JDXX1971]

Stainless cake pans are a popular and inexpensive choice. I would have gone that route but I can’t find one big enough for my 20G MLT. Turns out my unused 15G lid was a perfect fit for the 20G.

Yeah I just checked and the el cheapo super light weight lid to my 8 gallon pot fits in my 15 gall bayou classic, about as big as you could get in around the basket rim I think. There is about 1/4" all the way around once it is down in the kettle. How tight should the mash cap fit? I need to find one for my 20 gallon kettle now.

I am going to apply a few of the LoDo techniques to my next brew day, including the mash cap. I figure why not? Plus having a mash cap should help with thermal loss too, another reason I wanted to try one.

 

[schematix]

I have about 1/4” around the edges of mine too. May try to tighten it up a little but that’s like a 99% surface area reduction already

 

[MSK_Chess]

what about polystyrene foam? It floats, is inexpensive, can be cut to the exact size with ease, is relatively heat resistant (you can serve hot coffee in it) and is a good insulator of heat

 

[aeviaanah]

Here is mine. It's FDA silicone sandwiched between two pieces of SS.

 

[MSK_Chess]

I like the idea of using polystyrene, maybe covered with foil? you could even sit it on top of the grain while under letting and simply let the mash push it up.

 

[daveMN]

I used the lid from my old 10-gal igloo mash tun. Inverted and added locline. Mash cap plus insulated. Don't really need the insulated, since I'm E-BIAB, but it works well.

 

[mongoose33]

I like the idea of using polystyrene, maybe covered with foil? you could even sit it on top of the grain while under letting and simply let the mash push it up.

I'm trying to find a way to do this that doesn't involve aluminum foil. Like with copper, it contributes to Fenton Reactions. That, of course, is what Brewtan-B is supposed to help mitigate, but I'd like to move to a system where I can use less of it.

 

[CadiBrewer]

Anyone fly sparge with a mash cap setup? If so, how do you control the level of the water above your mash if you can't see it?

 

[Dland]

Anyone fly sparge with a mash cap setup? If so, how do you control the level of the water above your mash if you can't see it?

Add a sight glass to your mash tun. I have always used a lid anyway, since I brew outside. Keeps the snow, rain, insects, bird crap, etc out of mash.

 

[Jeff...]

Here is mine. It's FDA silicone sandwiched between two pieces of SS.
View attachment 554633
View attachment 554634

I like what I see and I already have the SS. Could you please reply back and let us know how well it works?

Thanks

 

[aeviaanah]

I like what I see and I already have the SS. Could you please reply back and let us know how well it works?

Thanks

As far as seal it works very well. You'll want to start large with the rubber disc and slowly take away till you get optimum seal.

 

[Jeff...]

As far as seal it works very well. You'll want to start large with the rubber disc and slowly take away till you get optimum seal.

I thought by it's design that it would work well. Thanks for verifying my suspicions. I was looking at food grade silicone dough rolling mats on Amazon. Some are already per marked with different diameters. Which would make measurements and cutting easy, even easier when it comes to trimming.

Thanks again

 

[aeviaanah]

I thought by it's design that it would work well. Thanks for verifying my suspicions. I was looking at food grade silicone dough rolling mats on Amazon. Some are already per marked with different diameters. Which would make measurements and cutting easy, even easier when it comes to trimming.

Thanks again

Your welcome, keep in mind what I hear silicone isn't the best material for blocking o2

 

[day_trippr]

Well...silicone tubing, because the material is thin (1/8") and the lengths are long with tons of surface area involved.
Otoh, that slab you're using is thick enough permeation isn't going to be a problem, not to mention the surface area is actually small compared to tubing runs found on the typical brew rig

Cheers!

 

[Jeff...]

Your welcome, keep in mind what I hear silicone isn't the best material for blocking o2

Silicone has to be better than nothing heck even saran wrap would be better than nothing...

I have a Rubbermaid 10 gallon cooler converted to a MLT. The inside diameter is the same on the top as it is near the bottom. It's should be relatively easy to get a good seal with silicon (I hope).

 

[day_trippr]

It'll be easy if there's enough compliance at the edge. I have an old thread here showing a silicone-gasketed FB for my old 10g Rubbermaid that never let a speck of grain get by...

Cheers!

 

[Bilsch]

Well...silicone tubing, because the material is thin (1/8") and the lengths are long with tons of surface area involved.
Otoh, that slab you're using is thick enough permeation isn't going to be a problem, not to mention the surface area is actually small compared to tubing runs found on the typical brew rig
Cheers!

Silicone does not put up much resistance to oxygen molecules moving through it and the thickness really doesn't slow them down much. Remember that piece of silicone rubber already has oxygen completely diffused into it before you even start your mash or what ever so they don't have to start traveling from one side to the other, because they were already in there. Think of it like a pipe filled with ping pong balls. If you put one more ball in the end of the pipe.. a ball will drop out the opposite end.

There are lots of cheap stainless lids, covers, pie/cake/pizza pans, trays etc out there. Regardless the size of your kettle, chances are some other lodo guy has already found something off the shelf that fits. Just ask us.

 

[day_trippr]

That totally makes sense, and I should have thought of that.
Just another reason why I made a career out of designing machines that only knew ones and zeroes

Cheers!

 

[Bilsch]

Silicone has to be better than nothing heck even saran wrap would be better than nothing...

I have a Rubbermaid 10 gallon cooler converted to a MLT. The inside diameter is the same on the top as it is near the bottom. It's should be relatively easy to get a good seal with silicon (I hope).

This is a common misconception for new low oxygen brewers.. but you do not want your mashcap to fit tightly or drag even slightly on the kettle walls. The cap must free float on the liquid surface and be able to very freely move up and down with the ever changing level. Even if you don't add or remove water, just altering the temperature will change the volume. If the cap cannot freely follow then either air will be sucked under the cap when the water level goes down or the cap will be swamped by the liquid at it rises.

 

[bkboiler]

I'm almost done with my last planning of my kettle rims build... Got two stainless pizza pans as "mash caps"...haven't modified them yet...
Stuck between two options:
1. installing weldless bulkheads in the center of the pans with ball valves and some sort of flow "diffuser" beneath the surface (NPT pipe cap with holes drilled?) to mitigate disturbing the grain
2. just drop in the pizza pan unmodded. there's 1/8" gap on each side...so if I shift it over to one side, I can just barely squeeze some tubing thru the gap...
it'll be pretty crushed, but as I understand the flow rate shouldn't be very high anyway.

how do you all avoid disturbing the grain bed?
fyi - I'm trying to avoid plastic where possible...

 

[Bilsch]

There are lots of solutions to diffuser. Some guys use a circle of loc-line, others a stainless disc deflector, some just a U shaped tube to turn the flow back upward and deflect off the bottom of the mash cap. I port my re circulation flow into the mash tun through a fitting in the side of the kettle then 90 degree upward through the grainbed to impinge off the bottom of the mashcap.

 

[Jeff...]

This is a common misconception for new low oxygen brewers.. but you do not want your mashcap to fit tightly or drag even slightly on the kettle walls. The cap must free float on the liquid surface and be able to very freely move up and down with the ever changing level. Even if you don't add or remove water, just altering the temperature will change the volume. If the cap cannot freely follow then either air will be sucked under the cap when the water level goes down or the cap will be swamped by the liquid at it rises.

It should be relatively easy to find a stainless steel something to float in the cooler. As others suggested a pizza pan perhaps.

 

[Bilsch]

It should be relatively easy to find a stainless steel something to float in the cooler. As others suggested a pizza pan perhaps.

Lots of restaurant supply stores with kettle lids and deep dish pizza pans etc. What is your cooler inside diameter?

 

[day_trippr]

It should be relatively easy to find a stainless steel something to float in the cooler. As others suggested a pizza pan perhaps.

Yeah, well, depends on how OC you are about fit. I've looked on and off for a couple of years for some SS baking or even pizza pan or the like that'd fit inside my 17-5/8" ID Blichmann 20g kettle without leaving a wide gap. I'm seriously thinking of having something fabricated at this point...

Cheers!

 

[bkboiler]

Thanks @Bilsch!

I think I'll use your method... I have a spare port in the side!

 

[Jeff...]

Lots of restaurant supply stores with kettle lids and deep dish pizza pans etc. What is your cooler inside diameter?

13" or 33cm would be a tight fit. Thinking maybe something like 32 1/2cm or 12 3/4" maybe a little smaller, if it needed to float

 

[Bilsch]

Yeah, well, depends on how OC you are about fit. I've looked on and off for a couple of years for some SS baking or even pizza pan or the like that'd fit inside my 17-5/8" ID Blichmann 20g kettle without leaving a wide gap. I'm seriously thinking of having something fabricated at this point...

So far in our experience the Blichmann kettles are the hardest to find a good fit. They are just odd sized compared to commercial cookware.

This one here might fit.
https://www.webstaurantstore.com/vi...ment-lid-for-60-qt-stock-pot/473SSCOVR10.htmlI have two of the 14" ones and I know from doing it that the outer lip can be bent back to vertical reducing the OD by about an inch. Could be tight though.

Also this might work..
https://www.webstaurantstore.com/vollrath-3717c-17-3-4-centurion-domed-cover/9223717C.htmlHowever I have no actual experience rebending this brand cap and it also has a bead round the edge which complicates that job.

This one looks like it might work but maybe due to the shape could trap air.
https://www.webstaurantstore.com/vo...ss-steel-cover-with-loop-handle/92247779.htmlIt has no bead and so you should be able to rework that lip.

It's hard to know what the final size will be but some of these are cheap enough you could destroy one finding out and not be to much out of pocket.

 

[Bilsch]

13" or 33cm would be a tight fit. Thinking maybe something like 32 1/2cm or 12 3/4" maybe a little smaller, if it needed to float

I think this one would be good.
https://www.webstaurantstore.com/vi...-qt-saute-pan-20-qt-stock-pot/473SSCOVR5.htmlOnce the lip is reworked you'd have just under 12" giving you 1/2" or so clearance which is pretty good for a mashcap. I know this brand and rebending the lip up is easy enough to do with just an adjustable wrench and about 1 hour of your time.

Here is a picture of the two caps of this brand I reworked. Both turned out nicely.

 

[day_trippr]

I had not considered trying to trim a stainless steel lid to fit.
Sounds hard core - thinking about my reciprocating saw chattering its way around trying to hold the diameter true

[edit] Now see the trick is in the bending, not cutting. Still, looking for something more turnkey if possible.

Speaking of caps...are there are any good examples incorporating an integrated recirculation return that doesn't plough up the grain bed?

Cheers!

 

[Bilsch]

Thanks @Bilsch!
I think I'll use your method... I have a spare port in the side!

Yep I had the upper port spare which was threaded on both sides (Spike V3) so I just have a nipple going to the center then a 90 going up. I measured the height of my typical grain bed and measured so the coupler you see threaded on there is about 1.5" above the grain bed. The reason I use that 1/2" SS NPT to 3" TC is that I'm using it as a wide flange to rest my mashcap on. This way it is in place when I do the underlet and just floats up on the water level as it comes up. This is the way the cap looks before the underlet and cap float.

 

[Bilsch]

Speaking of caps...are there are any good examples incorporating an integrated recirculation return that doesn't plough up the grain bed?

Lots of guys have drilled a hole in the cap and port the return through then use some kind of diffuser. The problem is that now you have added more weight to the mashcap and can easilly swamp it if the return hose isn't supported properly. Also long runs of silicone hose lose heat and increase your oxygen pickup through the hose. Best to keep recirc circuits short.

 

[Bilsch]

Here is another lodo brewers solution to mashcaps.

 

[Dustin_J]

Lots of guys have drilled a hole in the cap and port the return through then use some kind of diffuser. The problem is that now you have added more weight to the mashcap and can easilly swamp it if the return hose isn't supported properly. Also long runs of silicone hose lose heat and increase your oxygen pickup through the hose. Best to keep recirc circuits short.
View attachment 682084

How is that PTFE film tape on your hoses holding up - any issues at all?

 

[Bilsch]

How is that PTFE film tape on your hoses holding up - any issues at all?

Good so far going on about 1.5 year with the first application. Might need to be redone in another year or so.. we shall see.