# What's Your Settings? (digital Thermostats/fridgemates)



## rendo (9/2/10)

Hi Guys,

I got my ebay (STC-1000) Digital thermostat today. I was so excited that I had it wired up within 1-2 hours and testing it with a lamp and something cold from the fridge to drop the temp etc. It works a treat. (yes you do have to be comfortable with wiring & electronics, etc, it really isnt that hard, but if there is any doubt then get a sparky to do it)

Anyhow, I am wondering about two settings and what my fellow AHBers have them set at? I dont want to burn out the compressor on my fridge etc, but of course I want good beer. So what are your settings for:

1) Compressor delay?? 
I was thinking 5mins. The unit can go from 1min-10mins. Is 5mins fine or should I set at 10mins?

2) Temperature difference?? 
I was thinking 1degree. It can be from 0.3deg to 10deg. (temp difference setting means difference between your desired set temp and the current reading. Eg if your desired temp is 16deg, with a temp difference of 1 deg, this means the fridge will turn back on when it gets to 17deg. I guess all those with a fridgemate know this anyway)

Hope to hear soon as I am going to whack a brew down in the "brew fridge" by the end of the weekend (latest!)  It will be my first ever brew done in a fridge.

Thanks Guys, love this site!!


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## OzBeer_MD (9/2/10)

I have my tempmate set at 18 degrees C for Pale Ale fermentation (US05 lower for S04). The margin is set to 0.5 degrees but I am sure one degree would be fine. 5 minutes sounds pretty good for the compressor timer. 

I have had success strapping the probe to the side of the fermenter with a piece of styrofoam over it, as I am not really interested in the air temp but rather the wort temp.


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## raven19 (9/2/10)

1. Fridgemate/Tempmates have a built in delay of 3 minutes I think. Anything in the 3 - 10 minute range would be fine imo.

2. 1 degree should be fine.


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## rendo (9/2/10)

Ozbeer, you are a genius.Styrofoam is a great idea. I have been trying to think of something to use and that is bang on. A nice sized bit of styrofoam came with the dig thermo today. I now am getting it from the bin and will use it just for that! 



OzBeer_MD said:


> I have my tempmate set at 18 degrees C for Pale Ale fermentation (US05 lower for S04). The margin is set to 0.5 degrees but I am sure one degree would be fine. 5 minutes sounds pretty good for the compressor timer.
> 
> I have had success strapping the probe to the side of the fermenter with a piece of styrofoam over it, as I am not really interested in the air temp but rather the wort temp.


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## LethalCorpse (9/2/10)

The tighter you control the air temp, the tighter you control the wort temp. There have been numerous arguments on here about whether to give the probe some thermal mass (putting it in a bottle of water, styrofoam, etc), or leaving it in free air. If it's in free air, it will be able to more closely regulate the temperature. This may be at the cost of faster switching times, and higher power consumption and stress on the compressor. If you're more interested in the wort temp, the styrofoam is a particularly bad idea - it just slows down the response to the air temp, but still bears very little relation to the wort temp. For mine, I'd say power bills be damned and leave it in free air. If you must, a submersible probe in the wort wouldn't be a terrible idea either, but you'd want to set the temperature delta extremely low - this would be most advantageous for particularly ferocious yeasts, where the yeast itself will increase the temperature significantly. I'd probably go for the lowest possible dT and the highest possible compressor delay, with the probe in the air - this would result in the tightest temperature control without damaging the compressor. In all instances, a fan inside the fridge to circulate the air can be helpful, as it reduces the difference between the air temp and the wort temp. It will also pay to check the fridge seals - the more air can leak in and out, the worse the control becomes, and the more the compressor will need to run in order to maintain temps, just like with a normal fridge.


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## beerbrewer76543 (9/2/10)

High five for recycling!


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## rendo (9/2/10)

See your point(s) LC.....got me thinking again...(dangerous). Anyway, I will try with different methods, eg styrofoam, in free air, etc, Either way its now working a treat!

FANS!! Another top idea. I have a few decent 12V fans (i think 12V) from a big server(computer)/power supply. I could easily wire these up to a 12VDC power supply and stick say 2 or so of these in the fridge. What do you think about using these sorts of fans in the fridge? The moisture has ??'s hanging over my head. But otherwise I would say its a goer. Thoughts LC? Anyone?

Anyone else got any ideas? Time for a beer!

rendo.



LethalCorpse said:


> The tighter you control the air temp, the tighter you control the wort temp. There have been numerous arguments on here about whether to give the probe some thermal mass (putting it in a bottle of water, styrofoam, etc), or leaving it in free air. If it's in free air, it will be able to more closely regulate the temperature. This may be at the cost of faster switching times, and higher power consumption and stress on the compressor. If you're more interested in the wort temp, the styrofoam is a particularly bad idea - it just slows down the response to the air temp, but still bears very little relation to the wort temp. For mine, I'd say power bills be damned and leave it in free air. If you must, a submersible probe in the wort wouldn't be a terrible idea either, but you'd want to set the temperature delta extremely low - this would be most advantageous for particularly ferocious yeasts, where the yeast itself will increase the temperature significantly. I'd probably go for the lowest possible dT and the highest possible compressor delay, with the probe in the air - this would result in the tightest temperature control without damaging the compressor. In all instances, a fan inside the fridge to circulate the air can be helpful, as it reduces the difference between the air temp and the wort temp. It will also pay to check the fridge seals - the more air can leak in and out, the worse the control becomes, and the more the compressor will need to run in order to maintain temps, just like with a normal fridge.


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## LethalCorpse (9/2/10)

yup, they'd be fine. You can mount them anywhere, though best to have them pointed at the wort, and not at the probe


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## Yikes (9/2/10)

Controlling air temps does not control your brew temp as effectively because your brew will be warmer than the air temp during a vigourous fermentation. I have found this with my controller even just sticking it on the side of the fermenter with tape does not control the wort temp as effectively as sticking it on with some insulation material. 

Stick it on the side, add some insulation and watch the stick on digital temp stay rock solid!

Fans are a good idea. They shouldnt get too wet as long as you dont open the fridge every 20 mins like i seem to do.  

Thats my 2c.


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## rendo (9/2/10)

I'll check their current(am sure its 12V) and amperage...but i reckon they'd by a pretty low draw....say 0.3A at most...abosolute most...

So off a 12VDC 2Amp adaptor I could run quite a few of the suckers  I have about 8 or so of them and had no idea why I was keeping them, until now. I am thinking of using 2 or 3 only though. (yes, not pointed at the probe!  )



LethalCorpse said:


> yup, they'd be fine. You can mount them anywhere, though best to have them pointed at the wort, and not at the probe


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## MarkBastard (9/2/10)

Only one fan is needed, if at all.


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## Screwtop (9/2/10)

OzBeer this has all been covered before, delay times when using freezer/fridge etc, probe placement etc. Lots of reall good factual stuff.

Cheers,

Screwy


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## Greg Lawrence (9/2/10)

I dont think it really matters what you do with the probe as long as you KEEP THE DOOR SHUT!
Imagine that your fridge is full of water. When you open the door, all the water is going to fall/rush out all over the floor.
This is pretty much what happens to the cold air every time you open the fridge door.

My 2c.

Gregor


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## stew.w (9/2/10)

i would think a seperate bottle of water in the fridge would be useless.

1. because its smaller and would take a fraction of the energy to change the temperature

2 the yeast in the wort generate heat and water in the bottle doesnt, meaning that for the fridge to turn on the wort would need to heat the air and the air heat the bottle of water. which would mean a delay in the fridge turning on

i would have thought the best idea to be an insulated fermenter with the probe between the wall of the ferm and insulation


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## kamino (9/2/10)

I stick the temperature probe in a stubbie full of water at the back of the fridge. This method is a trade off between placing the probe in air (tightest control / lots of small compressor runs may shorten life of compressor) and placing the probe on/in the fermenter (poor control because of temperature undershoot).

This great post explains it way better http://www.aussiehomebrewer.com/forum//ind...st&p=411990 

In the post the guy puts a data logger on his fermenter with his fridgemate probe, fridgemate set to 18deg for a ferment. The datalogger showed that the min temp dropped to 13.7 every cooling cycle!!

Has anyone else here that places their probe in/on fermenter noticed this undershoot? I guess a temperature datalogger would be the way to measure it properly.


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## RdeVjun (9/2/10)

kamino said:


> I stick the temperature probe in a stubbie full of water at the back of the fridge. This method is a trade off between placing the probe in air (tightest control / lots of small compressor runs may shorten life of compressor) and placing the probe on/in the fermenter (poor control because of temperature undershoot).
> 
> This great post explains it way better http://www.aussiehomebrewer.com/forum//ind...st&p=411990
> 
> ...


Excellent post and link to quite a useful resource, I vaguely recall seeing it when it was posted, so thanks for the reminder. Yes, about the only way to know how your temp/fridge-mate is to log temperature as well, but that gets out of the reach of most hobbyists.

FYI, I am about to do the multiple temperature sensor per fridge thing. I have an elderly datalogger controlling my fridges however at the moment, just a single sensor in air for one (lagers) and a 2L bottle of water for the others (ales)- I probably should have them the other way around as the lager fridge does cycle quite a bit on a +/-0.5C threshold. I haven't paid a great deal of attention to the actual data yet, but I've scored some more useable temperature sensors (surplus, some elderly CS107s) and have the channels free in the logger (a CR10X, so 16 single- ended inputs, 8 control ports, ambient temp from the logger wiring panel too), so fairly soon I can hook them all up. I've got the convenience of logging power on cycles for count and duration with the control data too. 
Obviously I'll report my findings in due course, but I'm thinking the temperature threshold, wort temp fluctuation and the fridge cycling rate are all a bit of a balancing act for the thermodymamically- minded brewer. My brain isn't big enough for that so I'll just measure and adjust until I get what I want!


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