Notes on my
July 2013 build of the:
Son of Fermentation
Chiller
By rixxir
Original plans by Ken Schwartz, 1997 & 2003
I found the my well water here in the Boise, ID area runs
about 68-69° during the summer and the outside temps run usually 90-100° during
summer days with a 30-50° drop at night so I thought I’d make a water chilling
bucket for my fermentation vessel but I found that a constant trickle of cool
water was somewhat problematic with little temperature control so I decided to
go with Ken Schwartz's plans for a chiller.
It is a most efficient system with K.I.S.S. electronics and a minimal
investment.
I do have the advantage of a full wood shop with years of
tool accumulation but I also tried to consider the stuff available to most
DIY'ers in this build.
I collected some materials including:
- 1 - 2" extruded foam 4' x 8' sheet, (Pink Panther style, HD, ±$30)
- 1 tube of construction adhesive, (Loctite, Liquid Nails, etc.)
- Heating/Cooling thermostat, mercury type, $3 at a local recycle store.
- 12-volt power supply, (500 mA), $1 from the same store.
- 12-volt DC fan, 8cm, (3.149") (200 mA) from a computer supply store, ±$11
- 36 - 5/16" ID galvanized washers, about 1" diameter. I already had these in my shop but they are not pricy when bought in bulk. My local farm supply store sells them by the pound; the cheapest grade will do. About ½ lb. and $1.50 for the lot.
- 6' ± of ⅜" dowel stock, soft wood.
- 1 package of 17' long x ½" wide x ¼" thick open cell foam weather stripping, self adhesive.
- 1 roll of blue masking tape, 1" or 2".
- About 12’ of ½” x ½” wood for weather strip mounting.
I used my table saw to cut up the foam sheet. It does leave a nice edge especially if you
use a plywood blade, (many fine teeth), but I just used my multi-purpose
carbide blade and the edges are quite good enough.
Ken's cutting diagrams are spot on. Keep in mind that the FRONT, REAR, FAN, TOP
and BOTTOM panels have the same 16" width.
If you can, use a rip fence to keep these at the exact same width but do
what you can with what you have. I have
used an electric kitchen knife on foam sheets in the past but you have to have
a good straight edge to keep the knife perpendicular to the foam sheet.
The Pink foam has marks at 16" built-in so the first
cut is relatively easy.
When test fitting, I used blue masking tape to hold things
in place and also while the adhesives are setting up. This tape holds well and is quite easy to
remove without damage to the foam.
I cut the corners of both upper sides of the FAN foam piece
after using the fan I bought for a template.
Cut the corners with a fine-toothed saw or electric knife and use some
of the adhesive to secure the fan in place.
The blue tape does bugger up the foam weather stripping when
you try to remove it and the weather stripping doesn't adhere well to the pink
foam so I used some carpenter's glue and stick pins to hold that in place until
the glue dried. It does stick to the
wood well enough.
I finished the rest of the box construction before mounting
the thermometer and wiring the AC adaptor.
My big question was "How To Drill The Foam"
for the dowel fasteners.
Twist drill bits tend to tear out large chunks of foam and
it is hard to keep the bit centered, leading to a wandering center hole chewing
up the foam as it goes. I found that a
⅛" to ½" reamer I had worked well used in my ½" portable drill
to start a hole in the foam, using blue masking tape on the bit to mark a
stopping point at about ⅜" diameter.
A tapered drill bit is the big secret here.
I decided to try a tapered ⅜" wooden dowel to
drill out or widen the holes. This
worked very well. The foam is soft and
this bit drilled or pushed through the foam nicely with only a bit of squeaking
to show for it. The bit stayed centered
and you can drill all the way through the 2" foam easily.
I stopped drilling when the wooden bit pierced through to
the other side of the foam. Then I
drilled though from the other side with the reamer and then this wooden
bit. This leaves a nice tight hole that
is not ragged and is a good pressure fit for the dowel.
Using the wooden tapered bit without the reamer left the
holes too tight but I found that the reamer removed some of the foam and that
seems to make it better. Maybe a smaller
drill bit would remove some material and give you a better hole. Try ± 3/16”.
I used a 4-5" piece of ⅜" dowel for the bit. Chuck it in a drill and taper it down to a
point with files or sandpaper. Keeping
the point centered is important. It
keeps the "bit" from wandering.
You can get a nice snug fit of the dowel with this technique.
I used the washers instead of the brass grommet parts, only
because I had them lying around.
I put washers on the outside and inside of the SIDES and
also on the matching TOPS and FRONT. I
did split the TOP into 2 parts as Ken suggested.
I did have to countersink the washers on the inside of the
FRONT and TOPS for clearance. This was
also a concern because I didn't want the joining parts to bind or provide room
for leaks. I ended up using a 1"
Forstner bit to countersink the areas for the washers, just enough to keep the
TOP foam pieces from binding with the washers.
The Forstner bit in a drill press makes beautiful holes if you can use it
that way, but a little caulking helps with filling extraneous gaps you might
encounter hand hand-holding the drill in the process. If I do this project again I would pre drill
all the counter-sink holes I could on the drill press before assembly.
First I cut 12 dowels to about 4-5" and tapered one end
by sanding and inserted them in the foam, tapered end first. Then I glued the washers in place by dabbing
a bit of the adhesive on them and slipping them over the dowels to keep them
centered and used some masking tape to keep them in place until the adhesive
set up a bit. This keeps the washers
centered but do give the dowels a twist occasionally to keep them from getting
glued to the structure.
After the glue dried I used my ⅜" wooden drill bit to
drill through to both TOPS and FRONT panel holding pressure on the TOPS and
FRONTS while drilling with the wooden bit.
This makes for a tighter closure for the box when the dowels are
inserted.
Vinegar and apple cider 1 gallon jugs work well and are made
of better stuff than milk jugs. I
haven't considered using 4 frozen jugs yet as my temperature change needs are
modest at this point but I would use some support for the top jugs even though
these would probably be okay just stacking.
You'll notice the knobs on my dowels. They add better grip when pushing them in and
extracting them. I drilled out the knob mounting
holes to ⅜" and glued in the dowels.
After a few times inserting them they were easier move in and out.
The thin white piece just above the fan is a bit of 2”
aluminum blind piece held in place with thin mounting tape. This makes a nice platform for the weather
stripping, not adding too much height.
The
electronics were as per Ken’s diagram on page 9. The white thing is a remote temp monitor for
ambient readings. I will use a kitchen
type probe taped with a layer of insulation to my carboy or bucket to measure
wort temperatures and then I’ll mark corresponding spots above the thermostat
needle after things have stabilized. The
thermostat is held on with small thin bolts, fender washers and wing nuts
passed through 3/8” holes that allow for repositioning to make it level.
Small
staples pushed over the wires keep them out of the way and he power cord was pushed
through a small hole in the box and knotted with a figure 8 to keep it inside.
Fermentation
chamber is about 16” x 16” x 28” high.
Exterior
dimensions: 20” wide + knobs x 29” deep x 32” high.
Net weight
is just under 10 lbs. with power adapter.
A good
economy of weight and space compared to a fridge and the power consumption is
quite small.
I have since added an
aluminum pie plate in each jug compartment bent to fit the bottoms just to to catch condensation
but our desert climate keeps it dry anyway.
Testing:
July 2013
• ambient
temp in my garage with the box empty, 87°
• 2 -1
gallon frozen jugs added; thermostat set to ± 65°
• about 7
min. to reach 68° from 87°
• 66° in 10
min.
• 65° in 15
min.
• 65° in 20
min. – not bad for a low tech
thermostat!
I put a 3
gallon carboy with a 2.5 gal. batch of Irish Red Ale in and set the thermostat
to ±67°. The Fermometer tape read 72° on
the Better Bottle carboy but it had been ranging between 68° and 72° inside the
AC house using a water tray with a wet towel around it and a fan. Too much temp variation. This batch is about 2 weeks into secondary
fermentation and I’ll be lucky if I can save it but I’ll mark it up to R &
D.
I also taped
a meat thermometer probe on the bottle using a brick of pink foam to insulate
it from the box temp. (I am getting really
sick of PINK!) It registered 72° also.
24 hours
later, 65-66°
48 hours
later, 65-66°
About ¼ of the ice was left in each bottle. I'm very happy with the function of the box and the remote thermometer means I can monitor it from anywhere in my house.
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