Direct Heating Mash Tun - Burning

[Screwtop]

Have been directly heating my SS keg type mash tun for a while (5 batches). Using a 3 ring gas burner, usually only use the inner two or the middle ring. During the third mash using this method I detected a burnt mash smell, only slightly. When cleaning afterwards I removed the FB and there was some burnt/caramelised mash burnt onto the bottom under the FB. This carbon was really difficult to remove from the SS, took ages. After mashing today removed the FB again and there was a small amount of burnt mash there again.

A couple of questions for others using this method. 1. Could this be from too thin a bottom in the tun (keg). 2. Could it be from the bottom of the tun being too close to the burner as the centre which is closest to the burner is the worst.

I'm really enjoying the freedom of being able to step mash easily using direct heating, but don't want to be burning the mash. The reason I started direct heating using a gas burner was because I was having trouble with this same problem using a hand held immersion heater.

Screwy

 

[mika]

Could be a bit thin on the base for the amount of heat and how fast you want to heat it.
You can try thickening up the bottom, which may well slow the heat transfer rate. I have heard of people using the little ceramic bits and pieces like you use in the column of a :cough: water distiller. The idea is to end up with more surface area over which the heat is transferred. It'd be fun digging them out of the mash at the end of it all and to work properly they'd probably need to be under the false bottom to get the best contact with the bottom of the pot.
Couple of ideas for you.

 

[Pumpy]

Screwtop ,

I have been considering direct heat to my mash tun and been looking at Zwickles mash tun which uses a stirrer however I still think he raises the temperature gradually to avoid scorching the grain .so imagine his brewday takes a fair bit longer.

http://www.aussiehomebrewer.com/forum/inde...ic=7364&hl=

Pumpy

 

[Tony M]

Direct heating gives great flexibility with temp control and it is dead easy provided you keep the mash stirred. However with a false bottom, I dont see a practical way to keep the material in contact with the tun bottom agitated. It is easy with a perimeter filter. Here is mine.

 

[Zwickel]

wow Tony, beautiful work mate :super:

Screwy, to avoid burning the mash Im using pots with so called "sandwich bottom" thats a bottom made from many layers of metal.
have a look at the bottoms:
http://www.aussiehomebrewer.com/forum/inde...si&img=1055
that kind of bottom spreads the heat equable to the pot.
Also the stirrer is working permanent.

In your case, Id suggest you not to heat up with full power and the use of a permanent stirrer.
Also a kind of chimney (wind shield) would help, like this:

Some homebrewers have mounted a copper chain at theire paddel, it slides over the bottom to avoid burning the mash.

you may think over that.

Cheers

 

[sqyre]

hmmmm...

I'm curious, what would happen if you were to continuously circulate using a march pump while mashing?

possibly with a sparge arm or similar, under the lid to help keep the temp.

would a "stuck sparge" be guarranteed to occur from circulating for that amount of time??

That should keep the mash from burning in one spot as well as help to evenly distribute the heat through the mash...



Just a sunday night drunken uneducated thought...

sqyre..

 

[Zwickel]

hmmmm...

I'm curious, what would happen if you were to continuously circulate using a march pump while mashing?

possibly with a sparge arm or similar, under the lid to help keep the temp.

would a "stuck sparge" be guarranteed to occur from circulating for that amount of time??

That should keep the mash from burning in one spot as well as help to evenly distribute the heat through the mash...
Just a sunday night drunken uneducated thought...

sqyre..

Sqire, thats indeed a good idea, some homebrewer around here had tried that already, but they say the wort has been caramelized at the heating coil.

Another idea comes from a company that sells the "Speidel Braumeister", its a commercial version of a homebrewing system.

They keep the grain in a so called "grain tube" and the wort is pumped permanently through the grain tube and heated outside.

just have a look at it here:
http://www.speidels-braumeister.de/shop_co...sche-daten.html

Cheers :beer:

 

[ant]

hmmmm...

I'm curious, what would happen if you were to continuously circulate using a march pump while mashing?

possibly with a sparge arm or similar, under the lid to help keep the temp.

would a "stuck sparge" be guarranteed to occur from circulating for that amount of time??

That should keep the mash from burning in one spot as well as help to evenly distribute the heat through the mash...
Just a sunday night drunken uneducated thought...

sqyre..

My understanding is that very idea is the basis of a HERMS system; to continuously recirculate the wort during the mash. From what I've read and seen in action, you are *less* likely to get a stuck sparge because you are getting a nice compact grain bed, and you evenly distribute the heat through the mash.

This idea won't change any burning/scorching of the mash though, because the idea is to continuously circulate the wort, and not the grain. The grain itself will still be sitting on the bottom of the mash tun, so it will still be scorching.

If the idea is to continuously circulate the mash and not just the wort, I think you would be in for a difficult sparge... it would probably be easier to recirculate the wort and add a coil to the HLT (or separate HERMS unit) to avoid the scorching. Wouldn't it??? :huh:

 

[blackbock]

I'm glad this thread came up - I was hoping a FB would minimise the problem (currently working with s/s braid only.) Looks like, if anything, a FB makes the problem worse, because you can't stir under it. I have burnt a mash only once, but the taste is impossible to ignore. I noticed when it happened to me, the burnt region was a relatively small area right in the centre. Perhaps spreading the gas flame with a pipeclay triangle or similar may work?

Is there anyone who direct heats their mashtun with a NASA? Hot water infusions may be easier after all!

 

[blackbock]

I just had another idea. You could somehow use a water bath to heat the tun, just like chefs do when they melt chocolate. I might mull over this idea.

 

[Batz]

My understanding is that very idea is the basis of a HERMS system; to continuously recirculate the wort during the mash. From what I've read and seen in action, you are *less* likely to get a stuck sparge because you are getting a nice compact grain bed, and you evenly distribute the heat through the mash.

This idea won't change any burning/scorching of the mash though, because the idea is to continuously circulate the wort, and not the grain. The grain itself will still be sitting on the bottom of the mash tun, so it will still be scorching.

If the idea is to continuously circulate the mash and not just the wort, I think you would be in for a difficult sparge... it would probably be easier to recirculate the wort and add a coil to the HLT (or separate HERMS unit) to avoid the scorching. Wouldn't it??? :huh:

This is what I do ant,the HERMS coil is in a 20lt urn.
The mash is continuously recirculated,I can easly dial up step mashes with this system.I have never had a stuck sparge as yet ,with a double batch and big beers the flow is slower,this is because of the grain weight crushing the braid rather than a compressed grain bed.




The wort is taken from the mash tun value,pumped via the march pump (mounted under the switch board) then through the HERMS coil and back into the top of the mash tun.

Sorry for the hijack Screwy,not answering you question at all

Batz

 

[Screwtop]

Thanks for the replies brewers, all of the suggestions raise further questions, I do stir but as was pointed out you can't move the mash accross the bottom of a tun with a FB. Burning depends upon the mash schedule and type of grain. A mash of straight Pilsener burns a little over a 4 step mash, any mash containing 500gr or more of corn burns even on a single step. Zwickles sandwich base is the answer I think, seems the SS is too thin. Thought of having a thermowell dish welded onto the base of the tun. Maybe it's time for a HERMS like Batz, have a second HLT that I could put a coil into, all I'd need is a pump. Maybe a pottery heatsink under the tun might work. It's not that much of a deal as long as the FB is removed and the carbon scrubbed off after each use.

Made a fine Zwickel Pilsner yesterday and only had a small area of caramelisation under the FB. Thanks to Zwickel, will post his recipe for a North German Pils (Beersmith 24L batch) later today.


Does anyone have any suggestions as to what to use to remove the carbon, tried a little caustic solution, but still it was hard to remove, mostly SS scourer and elbow grease is required.

Screwy

 

[schubidubi]

I don't know if you like the Idea (it's not mine) but why not lifting the grains of the bottom like this home brewer:
http://www.thebrewingnetwork.com/phpBB2/viewtopic.php?t=4650

Hope I can help instead of asking questions all the time

 

[Pumpy]

I could put my immersion heater in a tall narrow SS pot and used one of those MashMate Hot Liquor & Mash Tun Temperature Controller DEI-106 to control the immersion heater then recirculate by pumping the the mash wort through it and back into the Mash tun like Batz, untill the wort was up to temp .


Pumpy :unsure:

 

[Tony]

i think thats called a RIMS Pumpy...... cant remember what it stands for.

i have a piccy of a cool invention i was on the net once, i have thought about building one but was worried about de-maturing enzmes by over heating the recirculating wort

Its just a piece of copper tube with a 2400W element jamed up the middle

probably not on subject but close

cheers

 

[tangent]

re-circulating (something starting with i) mash system

 

[BenH]

Screwtop (and others who directly heat their mashtun),

Do you insulate your mashtun?

I have a SS keg that is wrapped in a camping mat, but still find I lose an unacceptable amount of temp over a 60min mash.

I'm considering directly heating the mash tun but don't want to melt/burn the 'insulation'. (I have a copper manifold so will be able to stir the mash). On the other hand, I don't want to have to stand there and stir for 60 minutes, so would like to just bump up the temperature every now and then.

Cheers, BenH.

 

[Tseay]

Has anyone tried heating the mash using a hot water version of a chilling coil. Presumably you would have to add hot water initially. Would it just be too slow ?

 

[Screwtop]

Screwtop (and others who directly heat their mashtun),

Do you insulate your mashtun?

I have a SS keg that is wrapped in a camping mat, but still find I lose an unacceptable amount of temp over a 60min mash.

I'm considering directly heating the mash tun but don't want to melt/burn the 'insulation'. (I have a copper manifold so will be able to stir the mash). On the other hand, I don't want to have to stand there and stir for 60 minutes, so would like to just bump up the temperature every now and then.

Cheers, BenH.

My SS mash tun is insulated with a camping mat style rubber and a windshield insulation screen, heating gently using the inner two rings of a three ring burner is not a problem, tried using the outer ring but heat came up through the holes in the lower chime and the insulation got a bit sticky and smelly.

Good explanation of RIMS and HERMS HERE

Screwy

 

[Tony M]

Do you insulate your mashtun?
I have a SS keg that is wrapped in a camping mat, but still find I lose an unacceptable amount of temp over a 60min mash.
I'm considering directly heating the mash tun but don't want to melt/burn the 'insulation'. (I have a copper manifold so will be able to stir the mash). On the other hand, I don't want to have to stand there and stir for 60 minutes, so would like to just bump up the temperature every now and then.

Cheers, BenH.

I have 25mm of rockwool or fibreglass around mine. It doesnt mind the heat. I hit the empty pot for 30 or 40 seconds to warm it a little before I add the grain and water otherwise the mash temp drops a couple of degrees in the first five minutes as the SS tun slowly warms up. One more hit of two or three minutes about half way thru the mash is all the extra heating reqd. before mashout which is also quick and easy with two rings burning.