The inboard end is shown in the photo
below of the interior of the tun.
A drain was added to the bottom of the impeller housing to allow for complete drainage of the housing. This is needed since the rig is located in an unheated garage. It's a 6-32 thumbscrew with a O-ring that screws into a drilled and tapped hole in the impeller housing
Short pieces of 1/2" ID vinyl tubing with hose clamps marry the suction and discharge fittings to the adjacent 1/2" copper plumbing inside and outside the tun. They are secured with hose clamps. Fitting the 1/2" ID vinyl tubing over the 5/8" ends of the copper tubing is easy if the vinyl and copper tubing are first heated in hot water. The vinyl tubing functions as unions (permits easy assembly and disassembly) and also provides a bit of flexibility so that thermal expansion of the copper plumbing or bumping the plumbing doesn't over stress the pump's plastic suction and discharge fittings. (Thanks to Rick Calleyfor the tip! - his page).
The manifold at the bottom of the tun is a very important part of the RIMS since low recirc. flow is the bane of RIMSs. Although the grain bed is more important, alot of pressure loss occurs at the bed/manifold interface.
I much prefer a manifold over false bottom.
Based on playing around with various falsebottosm and manifold designs,
they seem to allow for much higher recirc. flow. The current manifold
is made of 1/2" copper tubing. It has LOTS of hack sawn slots!
To easy the tedium of sawing them and to make them uniform, a jig was used.
The Manifold page explains it.
The inboard tees of the manifold were hacked to serve as crosses.
Here's a photo
They were made by drilling a 1/2" hole thru the back side of the tee
via the bull outlet then filing and grinding the hole and the pipe-end
stop on the bull end of the tee out to 5/8" so the traverse tubing could
pass through it. The tee outlets along the run were left long
since I'd planned on not soldering those joints to allow for disassembly
for cleaning. Assembled, it had to be handled too carefully and the
mash had to be stirred carefully also so I abandoned that approach and
soldered them.
In the photo above, there's a piece of vinyl tubing with a hose clamp installed where the pickup tube from the manifold exits the tun. The thing serves several functions: to allow for removal of the manifold, to prevent the pickup tube from dislodging the copper coupling it fits into, to seal the joint air-tight and to provide a air vent. The air vent is important since the pickup tube forms an air trap when the tun is filled with foundation water and the resulting air "bubble" will greatly impede flow to the pump. After foundation water is placed in the tun, the pickup tube is not fully inserted in the coupling thereby exposing a 1/8" or so hole in the pickup tube which provides the air vent. Once the air has been dislodged (shaking the tun helps), the pickup tube is fully seated into the coupling and the vinyl tubing then covers the air vent hole and forms an air-tight seal. An air-tight seal is also needed to allow for complete drainage of the tun.
This is the part of RIMS design I enjoyed the most! Major features of the controller are a 2 line x 16 character LCD and 4 keys for an operator interface, solid state relays made from discrete devices, a real time clock, thermistors as temperature sensors, a piezoelectric sounder for alarms and additional feedback to the operator and finally an optional serial link to a PC which functions as a data logger. FWIW, others have built the controller with good results.
The controller is my own design. A schematic
appears below. It's brain is a $49 Basic Stamp II made by the fantastic
folks at Parallax Inc. This gizmo
is computer on a 24 pin IC. It's connected it to a PC via a
serial port and programed and debugged in Basic. Once programmed, it can
be disconnected from the PC. It has 16 i/o lines can be configured via
the programming to do all sorts of things like serial i/o for talking to
other another Stamp or PC, reading resistances, counting pulses or measuring
their width, generating DTMF for dialing phones, controlling X-10 wireless
120VAC control modules, pulse width modulation, etc. It's an amazing
device!!!
More Controller Info
The display shows the temperature at both RIMS thermistors, the RIMS set point, the elapsed time and the on/off status of both of the heaters. The temperature of the water in the hot water tank and it's set point can be displayed via pressing one of the keys. The set points for both the RIMS and hot water tank can be changed at any time via the key pad. When the set point is changed, the controller asks if the elapsed time should be reset (that's what the Dallas DS1302 real time clock chip is for). Until I incorporated a timer, I often forgot to keep track of rest times. This function is also available separately via the key pad is is handy for timing sparges as such. The piezo element doesn't do much at this point- it just emits soft beeps indicating when the heaters are on- different beeps for the two heaters. Since the STAMP is programmable, it's possible to program the entire mash schedule and let the controller take it from there. As the textbooks say, this is left as an exercise for the student :-).
The controller also includes an optional serial transmit only link to a PC with the PC acting solely as a data logger. I've written a simple little program for the PC that captures the data stream and writes it to a file for later analysis (holler if you want a copy). Some of the resulting time/temp graphs appear below. The data was imported into 123, distilled to 1 sample/sec. from the 2-3 samples/second in the raw data and graphed. Both mashes were done with the heater programmed to turn off with a wort temp. > 2 degF above the set point and a flow of about 0.5 GPM. You'll note that the temperature at the heater discharge continues to rise for another 2-3 seconds after the heater power is killed before peaking at 5 degF or so above the set point then pretty dropping rapidly. These peaks are much higher with lower wort flows- another good reason for making the best false bottom you can. OTOH, one could use a proportional or PID control algorithm rather than the simple "bang-bang" one I used...
For those of you who want a simpler electronic
thermometer or controller,
Ken
Schwartz has written a very nice page here.
Controller Programming
(Stamp2 BASIC source code)
Here's the main piece of the Stamp programming.
This is the other, supporting
piece of the programming which loads memory with lookup values the
Stamp uses to calculate temperature from the thermistor readings.
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| Changed the controller schematic and programming so that I/O pin 15 is free (it had been used for sending mash data to a connected PC via a 2 wire serial connection). The new serial link is 2 way and uses the programming port (physical pins 1-4 on the Stamp). I've dispensed with the Maxim RS232 driver with great results- communications are excellent at 1200 baud over 100' of cheap flat type telephone cable. |
| I now use one of Scott Edwards serial LCD "BackPacks" instead of the parallel interface on detailed on this page. This frees up several I/O pins (which I've not used yet...) and, more importantly, it greatly simplifies programming and resulted in smaller a program, so I... |
| Added a function to the controller program which allows the dT to be changed "dynamically" via the keys on the controller. (The dT is the difference between the set point and the temp. at the thermistor located downstream of the heater- if the programmed dT is exceeded, the controller cuts the heater off). Kinda useless for me tho' since the old 2 degF dT gives good results with no worries of scorching or denaturing the enzymes. |
| Added center off, DPDT switches to provide Hand-Off-Auto control for the heating elements. |
| Added a controller function which allows the RIMS heater to be turned on via some keystrokes thereby passing the automatic control. The program makes the beeper emit a terrible noise so I won't forget! |
False Bottoms A phil's phase bottom (which phloats!) did not work in the first RIMS I built- it caused way too much flow restriction. Dion (web site) uses one tho'. I think manifolds work better. I ran an experiment with a previous incarnation of my system to determine where most of the friction loss on the suction side of the pump takes place. I had a sight gauge attached to the piping between the tun and pump and to the tun just above a false bottom and ran a mash noting the difference in levels (i.e. pressure) between that gauge and the one in the pump suction piping. Most of the loss was in the grain bed- 8" there and another 2" in the false bottom and piping (all 1/2" copper) to the point where the lower sight gauge attaches. Almost all of the later loss is in the false bottom/grain bed interface since the flow was only about ~1/2 GPM. A similar mash with a manifold had only a 1/2" pressure drop in the manifold and piping and a higher flow rate (about 3/4 GPM).
Stoppers I used rubber stoppers for mounting the thermistors in the plumbing on an old RIMS. Do not try to fill the system without the one in the suction piping inserted or operate the pump without the other one inserted (DUH!). Yeah, I've done each of these bone headed things!
Heaters Do NOT operate the heaters without fluid (duh!). If you use alot of sparge water, it's quite easy to do with the heater in the HLT. Consider putting in a level switch affair which'll cutout the heater at a low water level. Do NOT operate the RIMS heater without flow through the heater chamber for it'll rather promptly scorch and perhaps even boil the wort in the heater chamber. If you are the type that's sometimes forgetful, consider electronically interlocking the heater with the pump.
Cleaning Run at least a batch of hot water through the system as a flush immediately after mashing. I usually flush twice, once with tap water then recirc with a gallon or so of 168 degF water for ~5 minutes. Drain well while the system is still hot and leave all the valves open to allow a bit of air to circulate an dry the innards. When system cools, close the valves and otherwise seal up the system. Before using, I recirc. a gallon or so of warm tap water for ~5 minutes and sometimes bring it up to 168 degF or so. This has served well - I've not had any deposits on the heater element other than a very thin mineral looking layer which gives the element surface a whitish appearance- much like water has dried on it (which it has).
I'd like ot someday add some hard and software to automatically control the level of water in the tun during sparging and to automatically control the RIMS pump speed based on the level of wort in the sight gauge. A flow meter would be nice too.
Use an old PC for the "brains". The system will still a the Stamp, but only as a interface to the RIMS. I like this 'cause I could keep my brewing notes/log on the PC rather than on scraps of paper. At least that's the theory!
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