Insulated Mash Tuns

Mark:   there are ways of controlling the amount of current delivered to a resistive device such as a heating element, one that comes to mind is chopper type device that cuts the current on and off similar to a light dimmer,  but more robust to handle the heavier current.  Of course the trick would be in calibrating such a device to come up with the temps required.........interesting thought.  Mashmaster market a digital controler mainly used here in Australia to control the temperature on a fridge or frezzer but can be used for heat control.  They sell for around the $AUD 50.00  See them on  http://www.craftbrewer.com.au 

Cheers

Brian

At work, one of my "specialties" is control systems.  I've designed and built heating systems that can control a 110VAC heating element to within two tenths of a degree C (though I admit none of them had to do with fluids other than air).

I can think of a couple ways to use a laptop to control it, but this is probably the easiest and cheapest (short of buying an off-the-shelf control unit, which is cheaper in labor but not as fun in my opinion):

What you want to do is plug your heater into a solid state relay, and use the RTS/CTS line on the serial port (aka RS-232 port, the one with 9 pins) of your computer to turn the relay on and off. 

For systems with very slow time constants, like heating large amounts of liquid in an insulated container, the only software control you really need is a loop doing a variable duty cycle with a period of, say, ten seconds.  Proportional control should be good enough, a full-blown PID controller is (probably) unnecessary.  A beginner who's used some sort of programming language could write and test the software within a week, with a little help.  The hardest part would undoubtedly be interfacing with whatever temperature sensor you pick.

If you want to tackle it and need some help with the algorithms, sensor circuitry, whatever, holler at me, I'm always willing to help.  That said, off-the-shelf temperature control units work amazingly well, come with a variety of interfaces, and their only real downsides are cost and, sometimes, lack of flexibility.

Yeah GOF I have been doing some up to date reading on PID's and seems the major problem with heating elements in liquid is that when you shut off the current at the so desired temperature the temp will still continue to rise. So a PID controller is a must in this environment to bring you accurately to the strike temps you are aiming at.  This is critical in a RIMS/HERMS setup.  As you say a computer is the ideal source for generating a simple program to control such a system whether it be partially manual or fully automatic. Even an old computer laying idle in the attic would do the job.  Also compensation for temperature drop between HLT and MLT via a march pump needs to be addressed, but I digress.  HB is an art where it will take you to where you want to go, from making beer juggling pots in the early years, to a "you beaut HERMS system" designed to suit your needs only limited by the boundaries of your skill and imagination.

Cheers,

Uh... Actually I was kidding about the laptop. But damn it now you've got me thinking.(never a good thing).
I work on control and data acquisition systems myself. I could easily come up with a program in Labview  to do the job in a couple hours. But I think maybe I'll do at least one AG batch before I get that carried away. I have to admit I do find some of the ingenious ways people have built the more complicated RIMS HERMS really intriguing. But as I said I'm a gadget freak.  But I think I'll have many more questions about just brewing than anything else for a while. At least I got an interesting thread going!

Thanks for the input.

Mark

Just last in line

I picked up a Coleman Xtreme 52 quart cooler and built a manifold inside out of copper and have a copper/brass drain setup. This method loses heat for sure and you can always tell by thermostat that the water near the drain valve is approx 5* cooler than the rest of the mash. I now wrap a towel around the outside spigot and it seemed to help on my last attempt. I have also found that preheating the cooler with hot water works but you need to leave the water in there for 15 minutes or so in order for the insulation to absorb some of the heat. Since I built the tun in the fall I also threw my coat over the cooler and even that seemed to help. Once I start doing 10 gallon batches and see how much the cooler will be filled, I'm going to figure out how to insulate the inside of the lid which will not only add insulation but reduce the airspace available for heat transfer.

I've read where plenty of people have very little heat loss and I'm sure with a little smart work I can also get the same.

MikeInCtown said:

Just last in line

...

Once I start doing 10 gallon batches and see how much the cooler will be filled, I'm going to figure out how to insulate the inside of the lid which will not only add insulation but reduce the airspace available for heat transfer.

I've read where plenty of people have very little heat loss and I'm sure with a little smart work I can also get the same.

Click to expand...

Insulating the lid.

Get yourself some rigid foam insulation.  In general it is blue but I think may be other colors as well depending on manufacturer.  It comes in a variety of thicknesses.  I think mine is three inches.  (Local hardware/building supply stores may have broken pieces.)

Find a couple of pieces large enough to fit right into the cooler.  Then, fashion a piece so it fits into the cooler and you can shove it down to just above the top of the mash mash.  In effect, you just created a mash tun that is costume made for your various grain and mash bills.