Is there a temp control unit that can cycle on and off at programmed time intervals

[hezagenius]

What I'm looking for is a temp control unit that, once triggered, will stay on for say 5 minutes, and then turn off, even if the target temp hasn't been reached. Then after an off-time of 5 minutes, it will click back on for 5 minutes and keep repeating that process until you hit the target temp. I'm trying to reduce big swings in temps.

Example:
Target temp: 66F
Cooling turns on at 67F
Heating turns on at 65F

When temp hits 67, the fridge turns on for 5 minutes.
After 5 minutes, the temp is 66.7. The fridge turns off.
After 5 minutes, the temp is 66.5. The fridge turns on.
After 5 minutes, the temp is 66.2. The fridge turns off.
After 3 minutes, the temp hits 66.0

 

[gfarantes]

I imagine you are using a thermowell in your fermentor. Since the liquid mass is quite large you get those temp swing. Try putting the sensor in a small bottle. The fridge will cycle a lot more but I believe the temp variation of the fermentor will reduce.

 

[brick_haus]

Well, I am no instrumentation guru, but I believe what you are looking for is a time delay relay. It would be installed in the line after temp controller and before the cooling unit (refrigerator).

 

[pocketmon]

It looks like an interesting algorithm.
I would bet BrewPi would do a better job than your algorithm. You might even be able to configure BrewPi to behave as what you describe if you run the latest 0.4.x version.

 

[swampbrewcrew]

This is a problem I ran into when I used a thermowell. The outside of the carboy would get frosty before the temprobe would read 60-70. I decided to ultimately quit monitoring wort temp and control ambient. I put my probe in a mason jar full of water and set it 3-4 degrees below target fermentation temperature. Once active fermentation starts to slow down I set the temp controller to the actual target fermentation temperature.

My freezer is in a garage in Mississippi where temps outside the freezer can be well over 100f sometimes. Placing the probe in a thermowell just didn’t work for me.

 

[beermanpete]

I think what you would need for this is a duty cycle controller or pulse-width modulation (PWM) controller. I know there are process controllers that can do this for heating applications. These devices may not work for a comprlessor however. I think the PID controllers are supposed to reduce overshoot by learning the behavior of the system and predicting the cycle times rather than simply reacting to a set-point.

 

[brick_haus]

Yes, if you wanted to step it up a notch from a td relay, you could always incorporate a PID with AutoTune (Accutune)function.
In my previous profession we would use Honeywell UDC 2500 properly configured to meet the needs of our process.

 

[Stealthcruiser]

Question: Is 5 minutes enough time generally, between on/off cycles for a compressor ?

 

[FunkedOut]

What I'm looking for is...
...to reduce big swings in temps.

A different approach would to monitor and limit ambient temps rather than cooling unit duty cycle.
Set a simple temp controller to limit the ambient temps 5 or 10*F below your desired wort temp.
Temp controllers are available everywhere and cheap.

 

[hezagenius]

Thanks for the info, everyone. For now, I put a thermowell in a tall glass of water.

My main concern right now is the heating side of things since my chamber is in my garage and the ambient temp in there is anywhere from around 40-60 degrees in the winter. During active fermentation, the fermentation generates enough heat to maintain itself in my chamber, but after a few days the temp dropped down to around 63F. My heater fan just isn't cutting it (not sure if it's a bum unit or it has some safety shutoff) so I put a light bulb in there. Man alive, that thing cranks out heat! After a few hours, I checked on it and the interior of the chamber was very warm to the touch and the fermenter (pony keg) was also warm on top but the temp reading had only gone up maybe 1 degree. So that got me thinking if there was some way to allow breaks in the temp control cycle to allow the temp to equalize a little bit before the next cycle kicked in. Seems like that could be something Inkbird could program into one of their units in the future sometime.

 

[gfarantes]

The temperature swing is directly related to the size of your glass of water.

 

[beermanpete]

Question: Is 5 minutes enough time generally, between on/off cycles for a compressor ?

No. The compressor needs to be off long enough for the pressure to equalize.

Thanks for the info, everyone. For now, I put a thermowell in a tall glass of water.

My main concern right now is the heating side of things since my chamber is in my garage and the ambient temp in there is anywhere from around 40-60 degrees in the winter. During active fermentation, the fermentation generates enough heat to maintain itself in my chamber, but after a few days the temp dropped down to around 63F. My heater fan just isn't cutting it (not sure if it's a bum unit or it has some safety shutoff) so I put a light bulb in there. Man alive, that thing cranks out heat! After a few hours, I checked on it and the interior of the chamber was very warm to the touch and the fermenter (pony keg) was also warm on top but the temp reading had only gone up maybe 1 degree. So that got me thinking if there was some way to allow breaks in the temp control cycle to allow the temp to equalize a little bit before the next cycle kicked in. Seems like that could be something Inkbird could program into one of their units in the future sometime.

There are controllers (Inkbird and others) that will control the cooling and heating and hold the temperature within the desired range without running both at the same time. Something like perhaps:

https://www.amazon.com/dp/B0743CK1FN/?tag=skimlinks_replacement-20

 

[hezagenius]

No. The compressor needs to be off long enough for the pressure to equalize.



There are controllers (Inkbird and others) that will control the cooling and heating and hold the temperature within the desired range without running both at the same time. Something like perhaps:

https://www.amazon.com/Inkbird-ITC-310T-B-Temperature-Controller-Greenhouse/dp/B0743CK1FN/ref=sr_1_10?s=industrial&ie=UTF8&qid=1511372262&sr=1-10&refinements=p_89:Inkbird

I use the non-B version of that. Normally I keep the probe in the thermowell in the middle of the fermenter but my concern is that by the time the liquid surrounding the thermowell hits the target, the liquid near the walls of the keg will either be hotter or cooler depending on if it's heating or cooling. So for now, I moved the probe to a glass of water.

What is an appropriate downtime for a kegerator compressor?

 

[beermanpete]

I don't know what the safe minimum off time is for the compressor. I think 30 minutes should be ok. I use a small chest freezer for fermenting and it only cycles a few times per day. If you have enough parts, move the temperature probe for the Inkbird to a small container of water in the kegerator near the fermenter and place a thermometer in the fermenter to monitor the wort/beer temperature. After collecting some data you should be able to establish an off-set that will result in the desired fermenting temperature.

 

[eric19312]

I've been using this
https://www.auberinc.com/index.php?main_page=product_info&products_id=671

to solve the problem you describe. I've had issues with big swings since changing to large fermentation volume (15+ gallons) controlled via probe in thermowell. My STC1000 was just not the right controller.

I looked at brewpi and brewpi spark to solve the problem. They provide advantage of dual probe and PID. But at expense of either big $$$ or needing a computer science degree to understand how to set it up. The Auber is not PID but provides the dual probe and does a nice job. Here is a chart from most recent brew. Note the TD500 doesnt have datalogging capability. I added a second thermowell and a RC-4 data logger to see what was really going on. Ths was controlled to 66F during first 6 days then bumped to 69 for days 7-11 and then cold crashed. Had a good swing in first few hours as fermenter adjusted to control.

 

[Horseflesh]

Thanks for mentioning the rc4! Been looking for a gizmo like that but had a hard time finding an inexpensive one.

 

[raysmithtx]

I've been using this
https://www.auberinc.com/index.php?main_page=product_info&products_id=671

to solve the problem you describe. I've had issues with big swings since changing to large fermentation volume (15+ gallons) controlled via probe in thermowell. My STC1000 was just not the right controller.

Do you leave the second probe just hanging in the fermentation chamber or do you place it in some sort of solution?

 

[eric19312]

Do you leave the second probe just hanging in the fermentation chamber or do you place it in some sort of solution?

The second probe hangs in the fermentation chamber. I program the controller to stop cooling when chamber is 5 degrees below cooling set point. This way if cooling set point is set to 66 and beer at thermowell is 68 the fridge will run if air temp in fridge is above 61. But once air temp in fridge hits 61 the fridge stops even though beer in fermenter is still above 66. When the air warms back up a bit fridge will turn back on...so long as it’s been at least 10 min (to protect compressor) and probe in thermowell is still showing beer temp over 66. Th hot set point and differential work same way 8n reverse.

 

[augiedoggy]

Depending on what system your using, You can also slow the flow of glycol or lower the power of your heaters or what not so it doesnt over cool your fermenters..
I mount my temp probes so they come down from the center top of my Conicals and due to the slow gradual temp drop I don't experience issues.

 

[The_Bishop]

This stuff has been hashed over dozens of times. Easiest way to do it without a bunch of fancy electronics is to place the temperature probe on the side of the fermentation vessel, with some insulation to partially isolate it from the chamber temps. I use an elastic band with a bit of foam.

 

[eric19312]

I am seeing issue with temperature control in first few hours before fermentation starts. Assume this is related to lack of mixing. Might be a reason for oxygenation / just bubbling air / during this period.

 

[fragged]

As several others have mentioned, a programmed solution is likely your best bet (BrewPi or custom). The proper Inkbird might do the trick as well, certainly for compressor time.

 

[bgmac]

I've been using this
https://www.auberinc.com/index.php?main_page=product_info&products_id=671

to solve the problem you describe. I've had issues with big swings since changing to large fermentation volume (15+ gallons) controlled via probe in thermowell. My STC1000 was just not the right controller.

I looked at brewpi and brewpi spark to solve the problem. They provide advantage of dual probe and PID. But at expense of either big $$$ or needing a computer science degree to understand how to set it up. The Auber is not PID but provides the dual probe and does a nice job. Here is a chart from most recent brew. Note the TD500 doesnt have datalogging capability. I added a second thermowell and a RC-4 data logger to see what was really going on. Ths was controlled to 66F during first 6 days then bumped to 69 for days 7-11 and then cold crashed. Had a good swing in first few hours as fermenter adjusted to control.

View attachment 546800

Eric, came across your post about the TD-500. I was in Alpharetta, GA (Auber Inst location) last week and stopped by their shop and picked up the TD-500. I was curious what you set your differentials at. I am shooting for 67F ferm temp. So I was thinking cooling CSP at 66.5F with a Cdf of 1 degree? And a heating HSP set at 67.4 with a Hdf of 1? Do you think that is enough spread on the dif to keep the cooling and heating from fighting each other? This is just for a 6 gallon batch. I plan to set the Cooling output limit CLL to 55 and Heating output limit to HLL to 80. Also was going to set the cooling anti-short to 5 minutes. Any advise? Thanks...

 

[eric19312]

Eric, came across your post about the TD-500. I was in Alpharetta, GA (Auber Inst location) last week and stopped by their shop and picked up the TD-500. I was curious what you set your differentials at. I am shooting for 67F ferm temp. So I was thinking cooling CSP at 66.5F with a Cdf of 1 degree? And a heating HSP set at 67.4 with a Hdf of 1? Do you think that is enough spread on the dif to keep the cooling and heating from fighting each other? This is just for a 6 gallon batch. I plan to set the Cooling output limit CLL to 55 and Heating output limit to HLL to 80. Also was going to set the cooling anti-short to 5 minutes. Any advise? Thanks...

I’ve got mine set at
CSP 66
HSP 65
Cdf 0.2
Hdf 0.2
HLL 72
CLL 60
Anti short 10 min.

16 gal in plastic fermentor (Spiedel) with beer probe in a thermowell and the Chamber probe in top rear corner of fridge. I run a computer fan in the fridge constantly.

Temps are very stable. Within +/- 1F throughout fermentation and I have no reason to suspect the fridge and heater are fighting each other.

Recently I’ve been transferring warm and letting chamber take the wort fro about 75 to 66 before pitching my yeast. For the first few hours I will drop my CLL to about 50, resetting it back to 60 when the wort is getting close to pitching temps.

 

[bgmac]

I’ve got mine set at
CSP 66
HSP 65
Cdf 0.2
Hdf 0.2
HLL 72
CLL 60
Anti short 10 min.

16 gal in plastic fermentor (Spiedel) with beer probe in a thermowell and the Chamber probe in top rear corner of fridge. I run a computer fan in the fridge constantly.

Temps are very stable. Within +/- 1F throughout fermentation and I have no reason to suspect the fridge and heater are fighting each other.

Recently I’ve been transferring warm and letting chamber take the wort fro about 75 to 66 before pitching my yeast. For the first few hours I will drop my CLL to about 50, resetting it back to 60 when the wort is getting close to pitching temps.

Thanks! I am going to reduce the differential a little to .5 and .5 and go with 67 cool and 66.5 heat. Should keep a 1+ degree spread. Normally it will just be cooling running or only heat depending on the season since its in the garage. Just thinking of that warm cool weather transition period where I will need both. This time of year I don't even have the heater in the space. I also run a fan in the chamber to keep the space even. Plus, I have had a fruit fly or 2 show up in the chamber attracted by the CO2/Ferm gases. The fan does a good job of keeping them at bay since they have a hard time navigating around with the air circulation. Haven't seen one inside since running the fan.