It's a 5 to 10 gal. RIMS using a rectangular
picnic cooler for the tun, a slotted manifold, sight gauge and a unique
controller and return manifold.
A Drawing and Photo:
The Tun & Fittings
I used a ~50 qt. Rubbermaid cooler which
has worked well- very good insulation and, after 20+ mashes, there's
no warping. To make it into a tun, after the drain valve was removed,
a 1/2 copper coupling fit nicely (with a bit of keg lube) through the rubber
grommet that remained in the hole in the cooler. On the inboard side,
a ~1" length of 5/8" ID vinyl tubing fits over the coupling and is secured
to it with a hose clamp. The 1/2" copper tube from the manifold slides
thru the vinyl tube and into the coupling. Well, before fully inserting
it, note on the drawing that there's a hole in the tube from the manifold.
It's for releasing trapped air from the manifold after the foundation water
is added. After air is bled-off (shaking the rig helps), the tube
from the manifold is fully inserted into the exit fitting.
.On the outboard end there's another ~1" length of 5/8" ID vinyl
tubing- much like the inboard end except another hose clamp is installed
further outboard. This acts as coupling for the modified tee fitting
at that end. Both of the above lengths of vinyl tubing are
install tight against either side of the grommet- this prevents the coupling
from moving when the manifold is remove or installed.
The inboard end is shown in the photo
below of the interior of the tun.
The pump is a March MDX-3. It a
plastic impeller housing and 1/2" OD barbed suction and discharge fittings.
I initially ran it at full speed and used the ball valve downstream of
it to set the recirculation flow. For the last year, I've used a
ceiling fan speed controller in the 120VAC power supply to the pump to
vary its speed and hence the flow. Not all fan controllers work with
March pumps- I tried a couple before I found the Lutron FS-5F which works.
This is better than twiddling the ball valve since the controller allows
for finer adjustment of the flow. I changed from a discharge throttling
valve to a motor speed controller since it'd been posted in the HB Digest
that pumps can damage enzymes. I've not noticed any changes
(e.g. faster conversion or changed f.g.) since the change, so the controller
hasn't been that much of an improvement.
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 Calley for the tip!).
All rigid tubing/piping and most of the
fittings exposed to wort are copper. The fittings used to mount the
thermistors and thermometer and the 1/2" valves on either side of the pump
are brass. A past Home Brew Digest thread indicated that many brass
valves have lead in the alloy to enhance the machineability of the brass.
At the temperatures and acidity during mashing, it's surmised that some
of this lead leeches into the wort. Brewer/metallurist John Palmer
posted that a soak in a peroxide solution will remove the surface lead.
Along the same line, only no-lead solder was used.
The Sight Gauge
I use a sight gauge to assess how much
pressure is available where it attaches to the plumbing or, looked at another
way, how much suction there is across the grain bed and manifold.
It helps avoid a stuck mash and pump cavitation. To me, it's invaluable!
With no flow, the level of liquid in the gauge is the same as the level
of wort in the tun (duh!). When the pumping, the liquid level will drop
by an amount equal to the friction loss of the wort traveling through the
grain bed, the manifold and plumbing to the point where the sight gauge
attaches. If there is alot of friction loss, the liquid in
the tube will be sucked from the gauge and into the pump followed shortly
thereafter by the pump attempting to suck in air- not a good thing!
Always start the pump at a low or no flow or and work up from there. I
try to maintain a pump speed which gives a level in the gauge about 2-3
inches or so below the bottom of the tun but it goes lower with a sticky
The Exit Manifold
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
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
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.
The Return Manifold
The return manifold returns wort to the
top of the grain bed in a gentle manner. To accommodate differing grain
bed heights, the level of the manifold is adjustable via the screw thing
shown in the second photo above. The business end of the manifold
has a cap at each end and a tee in the center that are secured via hose
clamps and 6-8 slots sawn in the fittings- tightening the hose clamps compresses
the fitting (due to the slots) and hence it grabs the tubing. This
allows for easy assembly/diassembly for construction and cleaning although
I've seldom had to clean the manifold since not much makes it thru the
small slots manifold at the bottom of the tun and what does readily clears
the 7/64" holes in the return manifold.
The heater chamber is made along typical
RIMS line using 1.5" diameter copper pipe and fittings except for the fitting
the heating element screw into- it's the end female end of a 1" bronze
hose fitting. It has straight threads which makes threading in the
heating element easy. Details are are shown in the photo below and
the drawing above.
The heating element is 240 VAC, 4500 W
watt density hot water heater element. Whatever you use has gotta
be of the low watt density type to avoid scorching of her wort.
A gasket that comes with the heater fits between the element and the end
of the chamber- it's this that makes the joint leak tight and not the threads.
The photo above shows the PVC elbow over the heater terminals which insulates
They are made from thermistors stuffed
into and sealed in 1/4" copper tubes. One is shown installed in the
above. Details on the probes and how to make them are on
the Thermistors for Brewery Temperature
The thermistor as well as the thermometer
fittings are modified 1/4" compression couplings. Basically, drill
out the fitting to 1/4", turn down one end until it's straight/smooth and
solder it into a hole in the plumbing. Nylon bushings are used
in the fittings. The electronic thermometer has a 1/8" stem, so a
bushing of 1/8" silicon tubing is placed over the stem before inserting
in the compression fitting.
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
More Controller Info
the Controller Works
Two conductor shielded twisted cable is used
for connecting the thermistors to the STAMP. I've since switched
to zip cord for the one on the HLT and it works fine. Therefore,
fancy cable isn't needed.
I used MOC3031 opto-isolators. They have a
zero-crossing feature which I feel is important in reducing EM interference
problems and also reducing the heat dissipated.
The triacs are Teccor 400V, 15A isolated
type, available from Digi-Key as part
no. Q4015L5-ND for $2.61 (as of 9/96). They also have the MOC3031 opto-isolator.
I mounted the controller in 3 enclosures.
There's a 4"x4" gang box which holds 2 duplex receptacles. Two outlets
are controlled by the triacs- the RIMS and sparge water tank heaters are
plugged into these outlets. The other 2 are just wired to the 12 ga., 3
conductor flexible cord that supplies power to the RIMS. The heat sink
onto which the triacs are mounted is fastened to this box. Aside the 4x4
box, I have a box which holds the optocouplers and a small 5 VDC linear
power supply for the controller. The box also includes jacks for the 3
thermistor cables and a DB-9 socket. The foregoing boxes are screwed to
the RIMS' frame. The remainder of the circuit components are in a 4x6"
plastic box that's attached to the DB-9 socket via a 8' or so piece of
shielded 9 conductor cable. This allows me to place the controller beside
a chair for easy monitoring. If you want to try a different mounting arrangement,
take steps to ensure the EMF and spikes the triacs generate don't interference-
i.e. scrambling of the STAMPS's brain and such.
Use a 120VAC circuit protected by a GFCI.
Having a GFCI doesn't eliminate the need for grounding tho'! Every piece
of exposed metal needs to be well grounded. I wrapped and soldered some
12 ga. copper wires onto the RIMS plumbing for this purpose. Soldering
isn't a "code approved" method tho'. A grounding cable clamp would be more
I power my system via a 120 VAC, 20 amp. circuit.
With 4.5kW, 240 VAC rated heating elements the average current is about
9.5A. A 15A circuit should work if there's no other big loads on the circuit.
Mount the triacs onto heat sink(s). The heat
sink I used is grossly oversized (2x4x1/2" and about 6 oz. or so). The
heat sink is just barely above ambient temperature during operation.
Stamp i/o pin 15 is used for connection to
a PC serial port. I've since found out that the programming port (Stamp
pins 1-4) can be used for this function also with a bit of wire swapping.
This frees up i/o pin 15 for another use. In addition, since this port
is bidirectional, one can use the PC it's connected to as the operator
interface and brains for the system.
I used the handy Maxim MAX232 RS-232 chip
and 50' of 2 conductor, 22 ga. zip-cord to tie the Stamp to a PC. I've
another Stamp project which transmits data to a PC reliably over 30' of
ordinary phone wire without the MAX232 but, YMMV! On a related note, the
Stamp doesn't output "real" RS-232 levels and some Stamp users have reported
problems getting their Stamps to talk to some models of portable PCs even
with short serial cables. There are some fixes for this problem I'm told.
The MAX232 chip would surely be one fix. Desktop PCs are reportedly immune
to this problem.
The controller controls both the RIMS
and the hot liquor tank temperatures. It monitors (via thermistors) the
temperature of the recirculating wort 1) where it exits the RIMS tun and
2) on the discharge side of the heater. It then controls the heater based
on these two temperatures. The heater is turned on ONLY when
the temperature at 1) is less than the set point AND the
temperature at 2) is less than the set point +2 degF (this dT can be changed
via changing the programming). The high limit cutout is needed (at least
IMHO) so that the recirc isn't overheated if the flow rate is low. Additionally,
since both the RIMS and the hot water heater tank are plugged into the
same 120 VAC circuit, the controller programming ensures both are not on
at the same time and trip the circuit breaker. Preference is given to the
RIMS- when it's heater is on the one in the hot water tanks is turned off.
Since I usually heat the water in the hot water tank before starting a
mash and the hot water tank is well insulated, this is not a problem. Even
on occasions when I've forgotten to preheat the water, tap water was brought
up to sparge temp. during the mash.
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,
Schwartz has written a very nice page here.
(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.
______ UPDATE ______ UPDATE
The controller info above is a bit dated and
needs revision, so, until then, a brief description of some of the modifications:
|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
|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!
and Using a RIMS
Here's info on commissioning
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).
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!
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.
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!
There's an old saw about standing on the
shoulders of others who've gone before you... here's some of the very kind
fellow homebrewers who've shouldered the previous work in RIMS design.
I'm deeply indebted to them!
Rodney Morris- the inventor of RIMS!
Dion Hollenbeck- author of a forthcoming
RIMS book. ( web site)
Rick Calley- a great gadeteer! (web
brewing expert! (web site)
Keith Royster I had a lot of help from
Keith! (web site)
van de Logt- a great HERMS system
3/03- First posted
Comments, Questions, etc...
If you've questions or suggestions I'd
really like to hear them! Please email me here:firstname.lastname@example.org
Use any and all of the above
for your own use for FREE! Use the stuff and make money with it and I want
some of the $$$! Use any and all of the above at your own risk. It works
for me but may not for you, i.e. YMMV.