Digital Thermostats

[bigfridge]

On a much sadder note....

It wouldnt have been a major loss except, as luck would have it, I was defrosting my main garage fridge and had moved my entire yeast collection (14 strains + back-ups), a 3 litre starter for the following days brew (Bock), a dozen assorted craft/imported beers and maybe the most painful of all my last bottle each of 5 y/o Imperial Stout and 4 y/o Doppelbock Id been so looking forward to cracking on Australia Day.

Smick,

Sad to hear of your loss mate. I can't replace the beer but you are welcome to come by and help yourself to my 'out of date' Wyeast 'bargain bin'. The packs are unsaleable (as nobody seems to want to wait a few days for them to swell) but the yeast is fine. I should have most of the strains available.

You would be doing me a favour to clear out some fridge space.

Dave

 

[The Mad Hopper]

I got one today and looked carefully at the thermo sensor under a lupe. I think it is molded onto the wire and should be moisture-resistant but I am probably going to put some silicon on it and some heat-shrink to seal the deal, so to speak...

The silicon I understand, and good idea. Heat shrink, I'm not familiar with. Could you elaborate?

 

[LethalCorpse]

Silicone and heatshrink are not necessary, or recommended. They're both pretty good at insulating, which will slow down the temperature response of your probe, giving you worse control over your temperature, meanwhile the food safe aspect of heatshrink is probably dubious (I know it doesn't taste great). If it's for fridge control, just leave it loose in the fridge - don't put it in a bottle of water or the wort or anything like that. If it's for heater control in an HLT, HERMS, RIMS, etc, use a thermowell, and put the probe in the end of the thermowell with heatsink compound. The humidity in a fridge won't bother the probe at all.

 

[kelbygreen]

main problem with the dodgy instructions giving is there is no instructions on wiring just a picture that doesnt show what wire is what just few black lines. after about 2 mins on the tempmate thread it all came clear very fast.

 

[QldKev]

main problem with the dodgy instructions giving is there is no instructions on wiring just a picture that doesnt show what wire is what just few black lines. after about 2 mins on the tempmate thread it all came clear very fast.

I think that is the point on here, the 'dodgy' wiring diagram actually means something about switched connections to those who can read it; if not don't electrocute yourself.


QldKev

 

[SpillsMostOfIt]

Heat shrink and silicone are recommended.

I will be using mine in a chest freezer used for a fridge which seems to generate a significant amount of condensation due to a lot of opening/closing and which clings to everything in the freezer until the surface tension gives up and it falls to the drain. I expect that probe to be quite bothered if left as it came out of the box. A small amount of silicon where the cable enters the molding is not going to present any significant insulation.

In said fridge, simply dangling a probe in free air leads to way too much cycling of the compressor. The energy consumption of this fridge has dropped substantially since I effectively 'worsened' the response of the probe as the compressor spends comparatively less time bringing the system up to an active cooling state over the course of (say) a day. I rely on the mass of the contents to keep them somewhere around the average of the temperature range inside the freezer. "Worse" control is actually a good thing; if you're looking for 'better' control then a different cooling system is appropriate.

 

[LethalCorpse]

define "too much cycling". You may have reduced the energy consumption (and I'd be quite curious as to how much energy is saved by increasing the cycle time), but you've also destabilised the temperature of your wort (again, wouldn't be massive, but still). Whether the benefits outweigh the costs is a matter for personal consideration, but for mine, if the objective is controlling the temperature I don't go and deliberately make my control system worse unless absolutely necessary. So long as the delay is large enough to prevent damage to the compressor (most of the decent thermostats have minimum time delays), it shouldn't be a problem. Some small amount of thermal mass would help increase the cycle time (the Jaycar kit comes with a small Al bar, for example), but sticking it in your wort or in a jug of water is overkill.

 

[rendo]

Guys,

Can I ask a dumb question? Okay, here is DQ #2....

I am pretty handy when it comes to wiring, soldering, circuit board work etc, but I have never tinkered with a fridge, so I shyed away from this stuff as I dont understand fridge wiring, compressors etc.

However if I am reading this right, the digital thermostat is simply an ON/OFF switch for the fridge (or freezer...whatever) based on the reading taking from the temp probe. So all the dig therms are basically a glorified power switch, based on a temp reading?

If so, then all I need to do is hack into the power cord of the fridge, wire up as per diag/instructions (easy peasy) and away I go??

If thats the case then BRING IT ON Woohoo...!!

Please tell me it is this simple (it looks it from the great instructions posted earlier in this thread)

 

[RdeVjun]

In a word rendo, yes. They're mostly just set- point with a dead band, so off at temp<setpoint-1/2threshold, on at temp>setpoint+1/2threshold. Or something like that.

A delay is to stop fools from setting threshold as minuscule and having the thing cycling rapidly, coolant compressors are none too pleased at being cycled too frequently, a handful of Hz at most.

 

[LethalCorpse]

Effectively, rendo, yes. But I can't recommend hacking it directly into your power cord. Wire up a box with a power inlet and outlet, as shown in this and several other threads.

 

[SpillsMostOfIt]

Previously, chest freezer in question was coming on at the end of each 'compressor delay' and running for maybe a minute or so. I have reduced the number of times the compressor runs in a period and extending the time for which it runs - now usually for about 4 mins. The amount of energy consumed is considerable - in theory because there are fewer 'compressor coming up to speed' events and also in practice. I don't have one of those plug-into-the-wall energy meters; I have to rely on the instrumentation of my inverter which covers the whole house and extrapolate a little. I reckon it was certainly tens of (24V) amp-hours each day, which is significant. (Even when I spent 6 hours pumping bore water up a hill yesterday, our total electricity consumption including the kitchen fridge, the beer fridge, the fermenting fridge and a chest freezer plus a sick wife wanting to watch Oprah and '30-Something' DVDs all day remained under 5kWH.)

With this device I'm keeping beer cool - not wort.

It is a silliness to try and keep the environment around a keg of beer at a constant temperature with a domestic fridge/freezer (that is why God gave us caves and cellars). The environment inside my freezer will see greater temperature swings than my fermenting fridge, but that's okay because it is doing a different thing. There is considerable thermal mass in four kegs of beer and a few tens of litres of air has to be quite cold indeed to move it in a hurry.

I support all those who fight the practice of immersing temperature probes into fermenting wort when using domestic refrigeration systems.

 

[The Mad Hopper]

I wouldn't have thought that having the probe free in the fridge would have used any more power than having any old fridge plugged in normally? (And I would have thought that it would have been much less, as the temperature differential between fermenting temp and room temp would be lower (than between room temp and 4C) and therefore warming of the fridge would take place more slowly and less compressor cycling would be needed).

 

[rendo]

Absolutely LC,

I use the word hacking rather loosely ...

I will do the job very neatly and safely.

I just always thought that to install a fridgemate (etc) that you had to cut other wiring and compressor controls etc etc, stuff I didnt fully understand. But really this is just a modification to the power cable. i.e glorified switch...

Thats great! Am going to buy one now for sure totally easy peasy...(at least for me)

Effectively, rendo, yes. But I can't recommend hacking it directly into your power cord. Wire up a box with a power inlet and outlet, as shown in this and several other threads.

 

[LethalCorpse]

But really this is just a modification to the power cable. i.e glorified switch...

No, it's not any kind of modification of the power cable. That's my point. It's a box which plugs into the wall, and then has a socket on it which you plug your fridge into. No modification of the fridge, or the fridge's power cable, is required.

You are right on glorified switch, though.

 

[Cortez The Killer]

Mine arrived today!

At the risk of appearing silly why do the Fridgemate, Tempmate etc have a spot for the earth cable?

While the ebay ones don't?

Cheers

 

[rendo]

Ohhhh....I see what u mean now. SO no modification to the actual cord...okay...GOT IT....

I am SO going to do this. I cant wait...

No, it's not any kind of modification of the power cable. That's my point. It's a box which plugs into the wall, and then has a socket on it which you plug your fridge into. No modification of the fridge, or the fridge's power cable, is required.

You are right on glorified switch, though.

 

[coe-crl]

Got mine today, going shopping at Jaycar tomorrow!


And I'm already thinking about ordering another 2.

 

[The Mad Hopper]

Mine arrived today!

At the risk of appearing silly why do the Fridgemate, Tempmate etc have a spot for the earth cable?

While the ebay ones don't?

Cheers

Offering up an answer (although LethalCorpse or someone else may correct me!). With the ebay ones, you run the earth from the cord, through to the fridge, without going into the box. With fridgemates etc, you run an earth into the box as well. It just means that while with both will earth the fridge, the ebay ones won't earth the box as well. (I'd assume it boils down to a cost thing)

 

[LethalCorpse]

In Australia, devices which are double insulated (ie, there are two layers of insulation between any mains wires or terminals and the user) do not need to be earthed. Anything with a metal chassis will usually be earthed. Since you're putting this in a plastic box, it shouldn't be a problem that it's not earthed, but there are probably a dozen reasons it wouldn't meet Australian Standards. RDWHAHB

 

[hatchor]

yep them instructions are very helpfull :lol: but it is easy to figure out once you look at the tempmate wiring posted over this site. Has any one tested these units for acuracy???

Tested mine 2 days ago using the same method as calibrating a mashmaster dial thermometer with a slurry of ice, and then boiling water. I also tested it against 50 degree water. It was measured against a thermal contact laser temp gauge, an Ikea brand digital meat thermo and the aforementioned MM dial thermo from my mash tun. The temp control unit was out by +0.3 degrees when others showed a flat zero, and measuring 50.8 degrees with the pre-existing thermometers showing a flat 50. At a flat 90 degrees the new temp control unit displayed 91.1 degrees.

So at zero, it is 0.3 degrees above. At 90 it is about 1 degree to high. Plenty accurate enough for controlling my fermenting environment!

Beers, :beerbang: