Direct Fired MLT?

Is it worth it. I aquired another keg today(legal). So I am thinking about doing away with the 10 gal rubbermaid. I would like some input from people who use this method. Obviously stirring while heating is a must. I would rather build a mash stirrer than a pump. Chime in with opinions please

I don't use this method, but am in the process of building a HERMS. I considered direct-fire but decided against it when I though about the unreachable space below the false bottom. Even if you stir religiously, you will still probably burn the wort/mash. You probably oughta stick with a pump. Pumps may be costly, but can be used for many different things in the process....from vorlaufing to whirlpooling cold break, to handling finished wort and sending it to a fermentor.

I've got a direct-fired keg MLT with a false bottom (very little dead space). I've used it for step mashes with no problem. I just keep the burner turned down low and stir constantly so that the temp changes gradually at ~ 2 deg / min. There's no burning or scorching. I'll add a pump soon to recirculate during the steps. This should eliminate the need for stirring.

FYI - Brutus 10 uses a direct-fired MLT. http://www.alenuts.com/brutus.htm

Good input, Brutha. I may have to take this into account. A direct fired MLT makes for a MUCH more simple plumbing setup.

I have a direct fired MT and love it. I do step mashing and mashouts with no scorching at all. I would recommend low heat and constant recirculation to assure no burning or hot spots. I use a march pump and recirculate through my sparge arm.

I will say that direct heat requires some attention, it's certainly not a set it and forget method unless you have mad skills ala Alenut of Brutus10 fame. I keep the heat down low, recirculate, and watch the temperature rise. When I get 1-2 degrees shy of my target temp I turn the gas off and allow the mash to creep to where I want it. This method suits my style, and keeps me hands on, I like it.

HERMS is a great alternative too, especially if you have an electric heating element in your HLT with a digi controller. No scorching, no babysitting, and assured consistent mash temps. Personally, I just like being more involved - but there a many ways to skin a cat.

One thing I forgot to mention is that I also really like being able to heat the strike water in the MLT. No preheating of cooler and lifting/pouring/transferring hot water from another pot.

It took me a while to dial in the strike temps as the keg holds a lot of heat, but now that I have it works great.

Ok, so just recirculating wort through the mlt keeps scorching away, right? Does it not make any difference to move the grains as well? Maybe I'll break down and buy a pump

I'm in the process of building my rig, and intend to go the direct fired route with a march pump, largely because i want to go all gas without electrical elements (ironic considering i'm an electrical engineer )

It'll be an custom electronic control system with a 25,000btu burner salvaged from an old old furnace

Good info on the direct fire. I recently got a good score on someone selling their gear, and have a spare 50' of 1/2" copper with 2 march pumps. My kegs are pretty much coupled already. I do like the mash arm though! I'm trying to come up with an acceptable method to return the wort to the top of the grainbed gently and without losing too much heat.

ScubaSteve said:

Good info on the direct fire. I recently got a good score on someone selling their gear, and have a spare 50' of 1/2" copper with 2 march pumps. My kegs are pretty much coupled already. I do like the mash arm though! I'm trying to come up with an acceptable method to return the wort to the top of the grainbed gently and without losing too much heat.

Click to expand...

The UPS Gods just delivered these from McMaster:

Material Polypropylene
Polypropylene Material Polypropylene
Backing Plain Back
Shape Balls
Ball Type Hollow
Diameter .787"
Translucent Translucent with White Tint
Highest Temperature +100° to +200° F
Operating Temperature Range Up to +190° F
Tolerance Standard
Specifications Met Not Rated

Quantity
150 | 2000

Quantity
150 3748K31 $15.71 per Pack of 150

2000 3748K21 182.18 per Pack of 2000

Sorry, McMaster's website makes it difficult to post a direct link that works. I plan on floating these on top of the mash to both insulate and provide a gentle path for the sparge water to return to the grain bed. Haven't tried them yet, hopefully next week, but I've got a LOT of balls.

edit: BTW, 300 of the 20mm balls provide a good cover in a 10 gallon round cooler.

Holy Schnykees, do you have balls!!

I'm absolutely intrigued by the use of polypro balls in the mash. I mash in a converted keg, and I only do 5 gallon batches which leaves a ton of empty volume in the mash tun. I've found that recirculation through a pump really creates a lot of heat loss. I can only assume that loss is due to the pump, not way wort is reintroduced to the mash or the MT insulation (when I pump I have the lid on AND bubble wrap around the keg and lid).

I wonder how much a heat might be retained by having the insulation sitting directly on top the mash? Very interesting.

ebeer said:

Holy Schnykees, do you have balls!!

I'm absolutely intrigued by the use of polypro balls in the mash. I mash in a converted keg, and I only do 5 gallon batches which leaves a ton of empty volume in the mash tun. I've found that recirculation through a pump really creates a lot of heat loss. I can only assume that loss is due to the pump, not way wort is reintroduced to the mash or the MT insulation (when I pump I have the lid on AND bubble wrap around the keg and lid).

I wonder how much a heat might be retained by having the insulation sitting directly on top the mash? Very interesting.

Click to expand...

With normal batches and a small grain bill I have about 1/2 - 1/3 of the cooler with dead air space. Each time I remove the lid I have to believe that I am losing heat. With the balls in place, it would be like having an insulated blanket sitting on top of the mash which should help. I guess I could come up with some sort of test to prove the theory.

I'd love to see a photo when you get it all set up Hopfan.

My feeling is that the heat loss I experience is less due to insulation, and more associated with the pumping.

I've been doiing loads of reading on HERMS and advantages/dis-advantages because I have some extra copper that I was trying to find a project for. There's quite a lot of theories on temp control, loss, gain, etc. The basic gist of what I take from it is that there is an associated heat loss due to the lines & pump being at ambient but it is not significant due to the speed of the fluids (once the lines & pump warm to the recirc temp) because those pieces are not very efficient heat dissipators. The reason I decided against HERMS, at this point, is because temp control is not necessarily better due to the fact that temp changes do not occur instantaneously throughout your mash. The output of the HERMS will normally be hotter than the rest of the mash and it takes a while to propogate throughout.

For minor temp adjustments, this would be fine, but I was most likely attempting to make up for any mash tun/HLT shortcomings and I didn't want to design in complexity to overcome something that has not been a big problem for me. The huge advantage to this system is that your mash runs extremely clear from the start of taking runnings due to the constant, or near constant, recirculation.

So now I have loads of copper that I think may become part of a tower cooling system once I build my coffin box for a draft system.