Show Us Your Stir Paddle For Your Direct Heat Mlt

[Hogan]

Having had pretty good success with single step infusion mashes in my rectangular esky with copper slotted manifold I have decided to venture into temperature step mashes. Whilst I have an immersion heater and have used it to good advantage in the past, I dont look forward to standing over the mash tun constantly stirring with the IH to get each step up to proper temp.

I have viewed some posts i.e Screwtops relating to direct heating of the mash tun and I am considering using a cut down 50lt s/s pot with a motor driven stirrer. I also want to mash out and sparge using a false bottom or braided s/s manifold as Tony M has done. I see from Screwys post there is a problem with grain burning at the bottom of the tun and that others on the thread have said that the use of a false bottom with a stirrer does not work.

I would appreciate views of setups from those who use the stirrer to keep the mash circulating whilst getting up to and maintaining step temperatures without grist burn. Particularly I would like your views on the following questions:

1. If your stirrer is driven by a motor, what type, size HP, torque does it have. (My grain bill has never exceeded 7 kilos or a ratio of 3:1)

2. How many arms does yours have? Depending on style would a one level arm turning at the base of the tun be sufficient to give proper temp circulation to my mash volume ie. 28 lts (grist and water combined) but more usually 20lts.

3. Do you use a s/s mesh manifold around the wall of the tun as shown in Tony Ms post.

4. Do you find that the s/s mesh collapses in on itself?

5. What heat source do you use? I have a HP wok burner that I use on my boils but I would think that something less powerful would be the go for maintaining a low temp during the mash.

6. Is your MLT insulated. If not, do you find that in a s/s vessel you are constantly raising and lowering the gas flame to maintain the temp. If you are insulated does the heat from the burner affect that insulation.

Cheers, Hoges.

 

[Screwtop]

Having had pretty good success with single step infusion mashes in my rectangular esky with copper slotted manifold I have decided to venture into temperature step mashes. Whilst I have an immersion heater and have used it to good advantage in the past, I dont look forward to standing over the mash tun constantly stirring with the IH to get each step up to proper temp.

I have viewed some posts i.e Screwtops relating to direct heating of the mash tun and I am considering using a cut down 50lt s/s pot with a motor driven stirrer. I also want to mash out and sparge using a false bottom or braided s/s manifold as Tony M has done. I see from Screwys post there is a problem with grain burning at the bottom of the tun and that others on the thread have said that the use of a false bottom with a stirrer does not work.

I would appreciate views of setups from those who use the stirrer to keep the mash circulating whilst getting up to and maintaining step temperatures without grist burn. Particularly I would like your views on the following questions:

1. If your stirrer is driven by a motor, what type, size HP, torque does it have. (My grain bill has never exceeded 7 kilos or a ratio of 3:1)

2. How many arms does yours have? Depending on style would a one level arm turning at the base of the tun be sufficient to give proper temp circulation to my mash volume ie. 28 lts (grist and water combined) but more usually 20lts.

3. Do you use a s/s mesh manifold around the wall of the tun as shown in Tony Ms post.

4. Do you find that the s/s mesh collapses in on itself?

5. What heat source do you use? I have a HP wok burner that I use on my boils but I would think that something less powerful would be the go for maintaining a low temp during the mash.

6. Is your MLT insulated. If not, do you find that in a s/s vessel you are constantly raising and lowering the gas flame to maintain the temp. If you are insulated does the heat from the burner affect that insulation.

Cheers, Hoges.

Hoges, Have made a slotted copper manifold and slipped braid over it (the larger braid from a gas hook-up). Still waiting for a slack mate to weld/braze it up for me, will let you know the outcome. Not being able to stir the bottom was a problem with direct heating the tun using the FB, but the freedom for step mashing cannot be beaten. Using a slap together HERMS at present but it can't step as quickly as direct heat. I used my original gas burner a 3 ring, mostly only use one or two rings.

My MLT was entirely insulated, had to remove the insulation from the bottom and for about 100mm up the sides at the bottom to stop melting the insulation. Held temp constantly over 60 min without any loss, think that the tun being heated helps here.

 

[Jye]

Hogan check out this article from Brewing Techniques, at has some good info on paddle design.

Link

 

[Hogan]

Hoges, Have made a slotted copper manifold and slipped braid over it (the larger braid from a gas hook-up). I used my original gas burner a 3 ring, mostly only use one or two rings.

My MLT was entirely insulated, had to remove the insulation from the bottom and for about 100mm up the sides at the bottom to stop melting the insulation. Held temp constantly over 60 min without any loss, think that the tun being heated helps here.

Thanks Screwy - that answers a couple of my questions. Can you get that gas braid at Bunnings?

One thing I missed out on in my first post was whether the base of a keg, being convex, will mess with the quality of the stir arm movement. Have thought of belting in the base to something more level or even welding a whole new base in over the top. The twin plates should give better heat distribution and lessen the chances of a burn - perhaps??

Jye- there's some good info in that page - thanks.


Cheers, Hoges.

 

[fraser_john]

Hogan check out this article from Brewing Techniques, at has some good info on paddle design.

Link

Jye,

what a great link you found! $50, wish I could get one made for that

I think stirring my mash is one of the more difficult jobs of the day, especially when brewing a high gravity 39 litre batch, its hard to get down the bottom and pull all the grain to the top.

 

[Screwtop]

Thanks Screwy - that answers a couple of my questions. Can you get that gas braid at Bunnings?

Cheers, Hoges.

That's where I got mine from

Screwy

 

[Tony M]

OK Hogan, this is a rough old webcam foto of my stirrer as it is now. I added the extra pair of blades (copied Zwickel!) and made them height adjustable to allow for varying grain bed depths. I use a motor from a garage door and run it thru a battery charger that gives me three speeds, 6V,12V & 24V and as you can see fitted to the top I have a detachable variable speed rotator which is what is needed for doughing in because the electric motor does not greatly agitate the mash but tends to rotate the whole lot like a great big pudding, though with a shearing action on the paddles there must be regular turning over of the mash. If I was clever with electricity that motor would be wired up so both the speed and direction of rotation varied then it would be set and forget.
4.The manifold braid does not collapse. When I was building this thing, I took some SS Mig welding wire and rolled it up into a coil and stuffed it into the braid.I feel that was unnecessary but others may guide you better here.
5. I use a 2 ring burner which works well. If you insulate your tun, once the temp. has stabilised, the heat losses over an hour are negligible. I find that I might be chasing a couple of degrees C after 40 minutes and by then I doubt it matters much.
6. I have an inch of fibreglass (or rockwool) insulation on the sides. It does char a little on the bottom edge but doesn't seem to care.

 

[Tony M]

Thanks Screwy - that answers a couple of my questions. Can you get that gas braid at Bunnings?

One thing I missed out on in my first post was whether the base of a keg, being convex, will mess with the quality of the stir arm movement. Have thought of belting in the base to something more level or even welding a whole new base in over the top. The twin plates should give better heat distribution and lessen the chances of a burn - perhaps??

It is simple to grind and/or bend your blades to fit the keg and a nightmare to try and fit the keg to the blade. A hydraulic hose shop will have that braid in several diameters and sell whatever length you want

 

[Screwtop]

Hoges, further to Jye's link have a look at using steam injection to raise mash temp steps, fairly simple and easily achieves 1C/Min.

Link

 

[tangent]

wouldn't steam injection be asking for a dose of HSA?

 

[Hogan]

Thanks Tony M - your info is appreciated

Hoges, further to Jye's link have a look at using steam injection to raise mash temp steps, fairly simple and easily achieves 1C/Min.

Link

Now there is food for thought Screwy. I happen to have a fully equipped pressure cooker sitting on my garage shelf.

Tangent I would think that the steam would be devoid of oxygen which should negate HSA. I would like to hear from someone less thermal dynamically challanged than me though on this issue.


Cheers, Hoges.

 

[Hogan]

Tangent - the author of the steam article does refer to HSA in the following:

Meanwhile, I dough in the mash at protein-rest temperature (or some other temperature, depending on the type of mash schedule I am using). By the time I am ready to raise the mash temperature, the steam generator is ready, as evidenced by the stream of steam emitted from the top of the cooker. This warm-up period also serves to purge any air from the cooker, which eliminates any worry about hot-side aeration effects from bubbling hot air through the mash. At this point, I replace the regulating weight onto the top of the cooker and open the valve to begin steam heating. The steam can be heard "bumping" inside the mash, and I stir frequently to keep the mash at a uniform temperature. Generally I can raise the temperature of the mash 1 C/min with no problems.


Cheers, Hoges.

 

[tangent]

doesn't boiling water produce O2? where does the gas come from? otherwise you could boil stuff in a sealed container.

 

[Guest Lurker]

Boiling water produces water vapour, not O2 gas. Its the same stuff, the molecules are just a bit further apart, and take up a bit more room.

 

[Hogan]

Tony M- your photo of the braid inside the tun shows four lugs holding the braid against the side of the MLT. Are these screwed or soldered in? If screwed I presume it is to facilitate removal and cleaning of the braid. How often do you have to remove it?

Cheer, Hoges.

 

[Tony M]

Tony M- your photo of the braid inside the tun shows four lugs holding the braid against the side of the MLT. Are these screwed or soldered in? If screwed I presume it is to facilitate removal and cleaning of the braid. How often do you have to remove it?

Cheer, Hoges.

Clean it ?????,
Actually the other day when I was hosing it out, I found an enormous well mashed and thoroughly dessicated slug stuck under the braid. Who knows for how many brews his spirit was present. I discovered that if I leave the pot upturned on the lawn after it has been hosed out, slugs and snails come in for a feed. Just another secret ingredient folks!
To answer your question, the lugs are welded in but I could bend them aside if ever I had reason to remove the filter.

 

[Hogan]

Clean it ?????,
Actually the other day when I was hosing it out, I found an enormous well mashed and thoroughly dessicated slug stuck under the braid. Who knows for how many brews his spirit was present. I discovered that if I leave the pot upturned on the lawn after it has been hosed out, slugs and snails come in for a feed. Just another secret ingredient folks!
To answer your question, the lugs are welded in but I could bend them aside if ever I had reason to remove the filter.

HaHa
Adds a whole new tilt to 'taking a slug'.

Cheers, Hoges.

 

[ant]

Tangent - the author of the steam article does refer to HSA in the following:

Now, after following numerous threads about temp of water while mashing in and direct pouring vs underletting I would of thunk that the bigger issue would be that you were heating the grain at the point of steam injection too much. If there are (perceived?) problems with water denaturing enzymes etc at ~70-75C, surely there would be at 100+C? (and yes, I realise that steam injection is how the big boys do it, but the volume of mash probably comes into play here).

 

[tangent]

i'm all for experimenting with new and weird ways but i'm keen on a gas fire under a metal tun with a paddle, or my keep cold and decoctions or infusions.

 

[Hogan]

i'm all for experimenting with new and weird ways but i'm keen on a gas fire under a metal tun with a paddle, or my keep cold and decoctions or infusions.

Tangent - After much ceiling gazing whilst in bed I have come to the conclusion that whilst steam could be a new and innovative way to heat the mash in the tun - there is just too much stuffing around involved in setting up the system to continue forward with it. Think I will just stick with gas on metal for the new tun.
But....the concept will remain in the memory bank.


Cheers, Hoges.