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Looking for Programable Digital Thermostat w/ short remote probe


Bill Velek

Jan 1, 1970
I'll get right to the point, and then add more info below for those who
want to read further. I don't know if this sort of a device exists, and
I've just spent all afternoon googling -- trying to find one -- without
any success at all. I hope that some kind person here will be able to
point me in the right direction. Thanks in advance for any help.

I'm looking for a programmable digit thermostat with a short probe that
just needs to reach about 2 inches through an insulated wall; in other
words, I want to mount the thermostat on the outside of a cabinet to
monitor and control the temp on the inside of the cabinet. I built the
cabinet a few years ago to ferment ale, but now I'd like to expand its
ability to include lagers which require more careful, critical control.

For ales, I used just a cheap household hvac thermostat mounted on the
inside, and there was no need for it to be programmable or even visible;
I just set it and forgot about it until the ale was done fermenting
about a week later. In fact, cooling was generally only important for
about the first 4 or 5 days, and the temperature requirements for ales
are so rough that most people don't use any cooling system at all except
perhaps to drape a wet towel over the fermenter to cool by evaporation.
I would just set my temp on 70F, and my system worked _very_ well. The
thermostat cycled a small fan (the type used to cool CPUs), and the fan
moved cold air from the lower ice compartment into the chamber where my
conical fermenter is suspended.

But lagers require _sustained_ cooling and conditioning, lasting perhaps
two months, with significantly cooler temps in the 35F to 55F range, and
with gradual, slow temperature changes (in contrast to ales which can
have a constant temp). If it isn't possible to program a thermostat to
constantly drop the temp at a controlled rate (e.g., 4-5F/day, max),
then I could manually lower the temp one degree every 6 hours or so, but
that would make having the control on the outside even more important.

What most homebrewers do is buy an old chest freezer and then change the
thermostat, but they usually use glass carboys as fermenters. I have a
conical fermenter which is too tall to put inside a chest freezer, and
my cabinet also doubles as the frame to support it. Besides, I'd really
like to try making a lager or two before deciding if I want to invest in
an extra freezer and converting it.

Also, if it turns out that my ice-cooling system isn't up to the job*, I
intend to try to augment the cooling by putting the system out in our
breezeway during the winter, but that presents the possibility of things
getting too cold, so I'd also like to be able to use the thermostat to
control some small heating device -- either a lightbulb or perhaps some
heat-tape like those used to prevent pipes from freezing. I figure that
the wires that usually control the air-conditioning will control my fan,
and those that control the heater will control my light-bulb or heating

*As for cooling power, the outside of my cooler is 16.5" x 16.5" x 34.5"
and it has 1.37" thick styrofoam (double 11/16") on all sides and top,
and 11/16" thick styrofoam between the two compartments. The lower
compartment can hold four frozen 1-gallon milk jugs, although I want to
play with that a bit because I'd like to suspend a 1/2-pint mason jar at
the bottom of my fermenter to collect yeast, etc.

Any comments or suggestions will be appreciated. I hope someone will be
able to help. Thanks.

Bill Velek -- remove the "--NO-SPAM--" from my email address


Jan 1, 1970
Hi Jim,
I'm not sure of how narrow a band/what range you need, but why not look
into a standard house thermostat. Most electronic ones use either a
thermistor or a diode to sense the temperature. All you'd need to do is
move thesensor into the box, and hang the rest outside.
Problem is that he needs a programmable step down for Lager beers.
Household versions are mostly limited to two programmed ranges, max
three. That wouldn't be enough for Lagers as far as I understood Bill.

On the other hand when we made Lager back at college we didn't know
about all this fancy stuff. Yet it tasted great.

Gruesse, Joerg


Jan 1, 1970
Hi Bill,
Well, I could actually get by without a programmable thermostat, if I
could just find one that goes as low as 34F/1C degrees, and a close
tolerance of not more than +/- 1F/.5C degrees (I guess you'd call that
the hysteresis??). I think that everyone that I've checked has a low
setting of 40F/5C. Without programming, I would need to set a
reminder to go and manually decrease the temperature setting every 12
hours or so; I'd want to lower it 2F degrees per day, so I'd just
lower the setting by 1 degree every 12 hours.

There are some thermostats that are going down to 0C or 32F, and some a
little lower. These can be used for maintaining frost free conditions in
pump houses and the like. So far I have only seen them in Scandinavia
but considering that the northern US and Canada are similar in climate
they just have got to be available here as well.

The hysteresis can usually be programmed. On our programmable thermostat
(Maple Chase brand) it comes out of the box set at 2F but can be
reprogrammed to 1F and I believe even zero. The nice thing about these
thermostats is that they have a backup battery so they don't lose time
and program. Ours actually has two and you alternate swapping them every
year. I guess they were worried about an outage happening just as you
change that battery. Pretty cool.
You were probably fermenting ales rather than lagers, or were perhaps
using lager yeast at ale temps. Ales ferment at room temp and take
only a week to ferment, and another week to carbonate in the bottle.
I've made lots of ales which were very good to drink 2 weeks after
they were brewed. Lagers, on the other hand, ferment at much cooler
temps (maybe 54F/12C), and then they are conditioned by slowly
lowering the temp about 2F degrees per day, down to 34 where they'll
usually sit for a few of weeks. They therefore require refrigeration
or cooling of some sort.

Probably you are right. It's been too long ago to remember. But we did
have to ferment in the basement where temps stayed pretty constant
around 60F all the time. These were old buildings in Europe where
basements are fully inground and the walls are a couple feet thick.

We never did this lowering of temps. I do remember one scary incident
though. We filled it into bottles and then some got stored in a
student's bedroom instead of the basement for whatever reason. Flip top
bottles. Some time at night a few bottles became grenades and that
triggered a cascade of kaboom. That was the last time we brewed beer :)

Regards, Joerg