Refrigerated fermenters - experienced views sought

Hi, I live on Queenslands Gold Coast - Australia. Recent summer temperatures have reached 30 indoors with nighttime temperatures dropping to only about 25. I have been starting my fermentation at around 22/24 using refrigerated water, but the brew temperature quickly climbs & my stick on strip has indicated highs of 29. Hard to know if this is an indicater of room or brew temp or both. The air conditioner has not helped much reducing temp of brew by only about 2.
Whilst my brews have survived & are somewhat better than I expected under the circumstances I clearly need to attempt some better temperature control. Cold tap water temperatures are about 28/30 so no relief here.
Putting the whole fermenter in a refrigerator seems the obvious next step but I am wary of the capability of the typical frifge thermostat.
Has anyone any personal experience of doing this in similar circumstances & if so was it worth the effort & what mods if any were made to the fridge controller.
Pete
Reply to
peterlonz
nothing but Pure Science and Absolute Environmental Control will yield a drinkable lager. i live in Alaska and i know a thing or two about the cold.
a friend of a friend replaced an ancient refrigerator with one manufactured in this century. i took it to a sterile laboratory and started to experiment. first, i moved the lawnmower to make room. then i put a carboy (with a temp strip) full of water in the lovely avacado-green unit, turned the temp controller to the "warmest" setting, and closed the door. i found that it got too cold so i cut a two foot section of the sealing strip from the top & bottom of the door. the plastic bit with the magnetic strip in it. i checked the temp over the period of a week and it was still tool cool. so i cut another foot (or so) off the strip on the bottom and after another week of checking it was spot on. the mass of the water (wort) keeps a fairly constant temp though i've never monitored with a temperature recorder to prove it. maybe later if i get a National Science Foundation Grant.
i've used it for a dozen or so batches of lager and the only other change i've made was a metal latch to keep my dog from opening the door with her curious nose. she knows a good thing when she smells it!
happy trails, dan .
Reply to
snowmannishboy

Yes lots, in an industrial setting. Needed refers to maintain a 20C temperature for chemical storage. I replace the thermostats with generic thermocouple controllers ~$50 each.
Only problem was encountered when someone decided tighter control was necessary (it wasn't the sampling technique was at fault). He tweaked the controller and as a result the overload that protects the compressor was always being activated - it lasted a week then died.
It wasn't hard to replace and only cost $10.
Compressors aren't meant to be turned off then back on, a short time later. The head pressure is too high and the motor stalls and overloads. They need to stay off long enough (several minutes) for the compressed gas on the outlet side of the compressor to dissipate through the evaporator valve.
A 5 gallon carboy doesn't change temperature quickly - so your refer will last longer if you don't insist on tight control (in process control terms "low hysteresis or deadband")
Most of the controllers that come with refers have a relatively large deadband but won't control temps that high.
You have two choices.
The easiest is to just add a separate electronic controller and plug the refer into it. Most generic controllers will set you back $50 or more. Set the deadband to 3-5 degrees and the compressor will last a long time. For instance: compressor runs at 23 degrees and shuts off at 17 degrees.
The downside is that the "defrost" timer (in frost free refers) will come on every 6-12 hours and shut off the compressor while the evaporator coils drip the water off ( that's a waste of energy - since they also turn on heaters to melt the ice and a 20C refer may never build up ice on the coils)
timer (it is a small clock driven switch usually accessible from the front of the machine). They are plug in devices as a rule, but unplugging it will cause the compressor to never run unless the right contacts are bypassed (there's usually a schematic inside the machine with all the info you need to make the right connection - or just cut the lead to the timer motor)
If you don't care about the energy waste it isn't important to disconnect the defroster.
Defrost timers also have a screwdriver slot that allow you to turn on the compressor when the timer motor fails (should it fail while defrosting - keeps the food safe and gives you time to get the right part). Good to know if you cut the wire during a defrost cycle.
The more difficult, but lots less expensive, choice is to recalibrate the internal thermostat. Most of the refers I've worked on have a bulb type controller. A gas or liquid is sealed in a stainless steel bulb with a thin capillary tube that goes to a bellows or "bourdon tube". When the temperature drops the working fluid (gas or liquid) contracts and the bellows or bourdon tube moves and mechanically activates a switch.
There is usually (but not always) some provision for adjustment of the control range and it usually consists of physically moving the switch with respect to the activator bellows. You have to take the controls apart to see it and determine if that option is the one you want.
The defroster will still operate, so you may still want to disable that.
It isn't particularly hard to recalibrate a refers controls - most of the time it is harder to figure out how to get at them. Refer controls very seldom fail in normal use so there's no incentive to make them easy to change. Every manufacturer has their own design philosophy - but the controls (the switch itself is almost always on the inside compartment and can be gotten at with a couple of screws (sometimes hidden under the control knob - which usually pulls right off or under a plate in the area of the adjustment knob(s).
The sensing bulb itself is usually close to the freezer compartment or evap coils - but it isn't necessary that you see it or get to it to recalibrate the controller.
Stay safe - unplug it before you play with it.
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