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-   -   Direct Fire MLT scenario (http://www.homebrewtalk.com/f51/direct-fire-mlt-scenario-198932/)

kegtoe 10-04-2010 04:03 AM

Direct Fire MLT scenario
 
Curently i have several vessels and i am alway changing my All Grain brewing. I guess i just like to mess around building stuff and tryin new things, ( and wasting money aparently :drunk:).

Anyway. I have 2, 10 gallon stainless pots. One i use as my hot liqour tank, the other i use as my boil kettle. i have a converted 5 gal cooler i use as mash tun. I also have an 8 gal electric kettle that i use RIMS style once in a while as my MLT. i have 2 propane burners - the 185,000 BTU bayou stands. They put out a lot of heat quickly.

I was thinking of going to a direct fire rims set up where i would add a 3rd burner and a 3rd 10 gal brew pot. I'm not sure why exactly i want to do this, other than asthetics (having all similar containers) and more pumping of the wort volume.

First, should i move to the direct fired system or just keep the systems i have. Second, if i do move to a direct fired setup should i do it rims style so i am always recircing my wort through the grains. and third, Would i want a less agressive burner? i heard some people say that the bayou burners are too powerful and not good for control.

kegtoe 10-04-2010 11:26 PM

any help would be appreciated

kladue 10-05-2010 01:35 AM

If you go to the direct fired RIMS style system you should drop down to the 6" cast ring burner as the amount of heat needed is not much and the 10" burners would not be happy at that low level. Recirculation during heating is required with wort temperature leaving bottom of MLT used to adjust burner flame, and mash temperature monitored for step duration. A needle valve in burner gas feed is recommended for finer control as you close in on desired temperature if step mashing, or setup for intermittent firing to maintain temperature.

Catt22 10-05-2010 04:28 AM

Kladue pretty much summed it up very well in a nutshell. Be advised that putting together and getting a direct fired RIMS to operate satisfactorily is not as easy as it would seem. I highly recommend automating the MT burner with a solenoid valve a la Lonnie's Brutus set up. Manually operating a RIMS burner requires constant attention and even then it can be tricky and tedious. A 6" low pressure ring burner would be an excellent choice for the MT. Avoid the multi-jet wok burners as well as the big banjo's for this application. The ten gallon kettles will be OK for 5 gallon batches, but too small for 10 gallon and larger batches. I think you will outgrow the 10's in a short time. I would highly recommend hooking up with someone who has an operating RIMS and schmooze him into letting you help him brew sometime. You will learn a ton from that experience and it will save you time and dollars in the long run. Lastly, go with a full width false bottom in your MT if direct firing and use a regular kettle instead of a converted keg if you can swing the cost.

wilceaser 10-05-2010 01:35 PM

How would a direct fire HERMS differ? Having your HLT direct fired, would your run more of a risk of unstable mash temps?

Catt22 10-05-2010 03:08 PM

Quote:

Originally Posted by wilceaser (Post 2318255)
How would a direct fire HERMS differ? Having your HLT direct fired, would your run more of a risk of unstable mash temps?

I don't have any experience with a direct fired HERMS, but I'm somewhat familiar with the basic principle. There's more than one way to plumb such a setup. Some use a bypass loop so that only a portion of the circulating wort passes through the HEX coil and this can be adjusted either manually or with automatic solenoid valves. Others are built without a bypass and some of these systems automate the pump control. There are quite a few variables to consider such as the size of the HEX coil and the volume of the HLT etc., etc, not to mention that you would need to stir or otherwise circulate the HLT water to keep it moving over the HEX coil.

So, to answer your question, as usual I would say it all depends. I chose a direct fired RIMS primarily for it's simplicity. The direct fired HEX seemed like it would be more difficult to operate without a whole lot of automation. I only automated my MT burner with a solenoid valve and temp controller. Everything else is manually controlled.

SweetSounds 10-05-2010 04:28 PM

Technically, what you are talking about IS a Direct-Fired HERMS system. The Wort is heated by passing it through a coil in a hotter liquid. Or are you pumping some of your wort into an empty kettle, heating it there, and pumping it back?

RIMS is very similar, but it heats the mash by passing it over a hot coil (Usually a water heater element)

Regardless, HERMS allows you to maintain great mash stability due to the huge thermal mass of the HLT volume. In other words, because the HLT is (let's say) 7 degrees above your target mash temp, it'll heat the wort while the wort tries to cool the HLT. Because the HLT thermal mass is large, it takes a lot of wort to bring its temp down because the relative difference in temp is only 7 degrees. (This is very similar to why ice is more effecient at the end of chilling - If you use ice when it's still 112 degrees, it melts very quickly)

The only down side is you'll have to manually chase the HLT temp with the gas regulator. (This is also why the Brutus was invented!)

Direct fire on the MLT is quite possible too, but I would think less forgiving than a HERMS because of the extremely fast temperature changes you can achieve due to the tiny volume of wort below a false bottom. I'm not sure I'd try it at all with a manifold down there - It would be really easy to scorch the grain that's laying on the hot metal.
I've seen it done (Can't find the thread right now) but it was automated. Again, it sounds like a lot of chasing the regulator to keep things in check.

erikrocks 10-05-2010 11:46 PM

From experience: a mash temp is extremely difficult to maintain through direct fired recirculation. I just ruined 10 gallons of stout because my thermometer didn't pick up the fact that my mash temp hit 180! I'm now going RIMS with a tube, PID, etc.

RiverCityBrewer 10-06-2010 12:38 AM

Quote:

Originally Posted by erikrocks (Post 2319723)
From experience: a mash temp is extremely difficult to maintain through direct fired recirculation. I just ruined 10 gallons of stout because my thermometer didn't pick up the fact that my mash temp hit 180! I'm now going RIMS with a tube, PID, etc.

I would disagree simply because a bad thermo can screw you with a RIMS tube as well... I direct fire my mash tun and control the burner with a BCS and I can hold +/-.5 F , but before I did that I did it manually and checked with 2 thermos and never had an issue.

kegtoe 10-06-2010 12:39 AM

I'd love to automate something but i dont understand electrical instrumentation for nothing. I dont know what SSRs do, i dont know how to program PIDs and i don't even know how wire all that **** together.

Also can someone recomend a solenoid for propane?


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